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Achondroplasia (ACH), the most common form of human dwarfism, is caused by an activating autosomal dominant mutation in the fibroblast growth factor receptor-3 gene. Genetic overexpression of C-type natriuretic peptide (CNP), a positive regulator of endochondral bone growth, prevents dwarfism in mouse models of ACH. However, administration of exogenous CNP is compromised by its rapid clearance in vivo through receptor-mediated and proteolytic pathways. Using in vitro approaches, we developed modified variants of human CNP, resistant to proteolytic degradation by neutral endopeptidase, that retain the ability to stimulate signaling downstream of the CNP receptor, natriuretic peptide receptor B. The variants tested in vivo demonstrated significantly longer serum half-lives than native CNP. Subcutaneous administration of one of these CNP variants (BMN 111) resulted in correction of the dwarfism phenotype in a mouse model of ACH and overgrowth of the axial and appendicular skeletons in wild-type mice without observable changes in trabecular and cortical bone architecture. Moreover, significant growth plate widening that translated into accelerated bone growth, at hemodynamically tolerable doses, was observed in juvenile cynomolgus monkeys that had received daily subcutaneous administrations of BMN 111. BMN 111 was well tolerated and represents a promising new approach for treatment of patients with ACH.

Object Achondroplasia may be associated with compression at the cervicomedullary junction. Determining which patients are at greatest risk for neurological complications of cervicomedullary compression can be difficult. In the current study the authors reviewed their records to determine the incidence and clinical significance of dynamic cervicomedullary stenosis and obstruction of CSF flow along with surgical outcomes following posterior fossa decompression. Methods The authors reviewed 34 consecutive cases involving symptomatic children with achondroplasia undergoing cervicomedullary decompression performed by a single surgeon over 11 years. Of these patients, 29 had undergone preoperative dynamic MRI of the cervicomedullary junction with cine (cinema) CSF flow studies; 13 of these patients underwent postoperative dynamic MRI studies. Clinical outcomes included changes in polysomnography, head circumference percentile, and fontanel characteristics. Radiographic outcomes included changes in dynamic spinal cord diameter, improvement in CSF flow at the foramen magnum, and change in the Evans ratio. Results Patients were predominantly female, with a mean age at presentation of 6.6 years and mean follow-up of 3.7 years (range 1–10 years). All patients had moderate to excellent improvement in postoperative polysomnography, slight decrease in average head circumference percentile (from 46.9th percentile to 45.7th percentile), and no subjective worsening of fontanel characteristics. The Evans ratio decreased by 2%, spinal cord diameter increased an average of 3.1 mm, 5.2 mm, and 0.2 mm in the neutral, flexed, and extended positions, respectively, and CSF flow improved qualitatively in all 3 positions. There were no postoperative infections, CSF leaks, or other major complications. None of the patients undergoing initial foramen magnum decompression performed at our medical center required reoperation. Conclusions Patients with achondroplasia and symptomatic cervicomedullary compression have increased risk of dynamic stenosis at the foramen magnum evident upon dynamic cine MRI. Operative decompression may be offered with low risk of complications or need for reoperation.

Fibroblast growth factor receptor 3 (FGFR3) is the only gene known to cause achondroplasia (ACH), hypochondroplasia (HCH), and thanatophoric dysplasia types I and II (TD I and TD II). A second, as yet unidentified, gene also causes HCH. In this study, we used sequencing analysis to determine the frequency of FGFR3 mutations for each phenotype in 324 cases from the International Skeletal Dysplasia Registry (ISDR). Our data suggest that there is a considerable overlap of genotype and phenotype between ACH and HCH. Thus, it is important to test for mutations found in either disorder when ACH or HCH is suspected. Only two of 29 cases with HCH did not have an identified mutation in FGFR3, much less than previously reported. We recommend testing other mutations in FGFR3, instead of just the common HCH mutation, p.Asn540Lys. The mutation frequency for TD I and TD II in the largest series of cases to date are also reported. This study provides valuable information on FGFR3 mutation frequency of four skeletal dysplasias for clinical diagnostic laboratories and clinicians.

The presence of cardiovascular abnormalities in patients with spontaneous cerebrospinal fluid (CSF) leaks are not well-documented in the literature, as cardiovascular evaluation is not generally pursued if a patient does not exhibit additional clinical features suggesting an inherited connective tissue disorder. We aimed to assess this association, enrolling a consecutive group of 50 patients referred for spinal CSF leak consultation. Through echocardiographic evaluation and detailed medical history, we estimate that up to 20 % of patients presenting with a spontaneous CSF leak may have some type of cardiovascular abnormality. Further, the increase in prevalence of aortic dilatation in our cohort was statistically significant in comparison to the estimated population prevalence. This supports a clinical basis for echocardiographic screening of these individuals for cardiovascular manifestations that may have otherwise gone unnoticed or evolved into a more severe manifestation.

Short-rib polydactyly (SRP) syndrome type III, or Verma-Naumoff syndrome, is an autosomal-recessive chondrodysplasia characterized by short ribs, a narrow thorax, short long bones, an abnormal acetabulum, and numerous extraskeletal malformations and is lethal in the perinatal period. Presently, mutations in two genes, IFT80 and DYNC2H1, have been identified as being responsible for SRP type III. Via homozygosity mapping in three affected siblings, a locus for the disease was identified on chromosome 9q34.11, and homozygosity for three missense mutations in WDR34 were found in three independent families, as well as compound heterozygosity for mutations in one family. WDR34 encodes a member of the WD repeat protein family with five WD40 domains, which acts as a TAK1-associated suppressor of the IL-1R/TLR3/TLR4-induced NF-κB activation pathway. We showed, through structural modeling, that two of the three mutations altered specific structural domains of WDR34. We found that primary cilia in WDR34 mutant fibroblasts were significantly shorter than normal and had a bulbous tip. This report expands on the pathogenesis of SRP type III and demonstrates that a regulator of the NF-κB activation pathway is involved in the pathogenesis of the skeletal ciliopathies.

To investigate human long bone development in vivo by analyzing distal femoral epimetaphyseal structures and bone morphometrics on magnetic resonance (MR) images of fetuses.An institutional review board approved this retrospective study, and informed consent was waived. Included were 272 MR imaging examinations (April 2004-July 2011) in 253 fetuses with a mean gestational age (GA) of 26 weeks 6 days (range, 19 weeks 2 days to 35 weeks 6 days) without known musculoskeletal abnormalities. Two independent readers qualitatively analyzed epiphyseal and metaphyseal shape, secondary ossification, and the perichondrium on 1.5-T echo-planar MR images and correlated the results with the GA that was derived from previous fetal ultrasonography (US). Diaphyseal and epiphyseal morphometric measurements were correlated with GA by means of the Pearson correlation and linear regression. MR imaging measurements of diaphyseal length and US normative values were compared graphically. Interreader agreement analysis was performed with weighted κ statistics and the intraclass correlation coefficient.With advancing GA, the epiphyseal shape changed from spherical (r(2) = 0.664) to hemispherical with a notch (r(2) = 0.804), and the metaphyseal shape changed from flat (r(2) = 0.766) to clearly undulated (r(2) = 0.669). Secondary ossification (r(2) = 0.777) was not observed until 25 weeks 3 days. The perichondrium decreased (r(2) = 0.684) from 20 weeks onward. Correlation coefficients were 0.897 for diaphyseal length, 0.738 for epiphyseal length, and 0.801 for epiphyseal width with respect to GA. The range of measurements of diaphyseal length was larger than that of the reported US normative values. Interreader agreement was good for bone morphometrics (intraclass correlation coefficient, 0.906-0.976), and moderate for bone characteristics (weighted κ, 0.448-0.848).Prenatal MR imaging allows visualization of human bone development in vivo by means of epimetaphyseal characteristics and bone morphometrics.http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13112441/-/DC1.

Arterial complications are common in vascular type Ehlers-Danlos syndrome (EDS), accounting for 66% of first complications. Several cases in the literature have documented acute compartment syndrome (ACS) following vascular rupture in vascular type EDS. Other disorders of connective tissue have also demonstrated vascular fragility, leading to arterial aneurysm and rupture, but there have been no documented cases of ACS. Here, we report on a female patient with a history of recurrent compartment syndrome who exhibits some clinical findings seen in hypermobile and vascular EDS; however she does not meet clinical and molecular diagnostic criteria for either of them. We further review the literature on ACS in heritable connective tissue disorders and suggest that compartment syndrome may rarely complicate other heritable disorders of connective tissue.

Bent Bone Dysplasia-FGFR2 type is a relatively recently described bent bone phenotype with diagnostic clinical, radiographic, and molecular characteristics. Here we report on 11 individuals, including the original four patients plus seven new individuals with three longer-term survivors. The prenatal phenotype included stillbirth, bending of the femora, and a high incidence of polyhydramnios, prematurity, and perinatal death in three of 11 patients in the series. The survivors presented with characteristic radiographic findings that were observed among those with lethality, including bent bones, distinctive (moustache-shaped) small clavicles, angel-shaped metacarpals and phalanges, poor mineralization of the calvarium, and craniosynostosis. Craniofacial abnormalities, hirsutism, hepatic abnormalities, and genitourinary abnormalities were noted as well. Longer-term survivors all needed ventilator support. Heterozygosity for mutations in the gene that encodes Fibroblast Growth Factor Receptor 2 (FGFR2) was identified in the nine individuals with available DNA. Description of these patients expands the prenatal and postnatal findings of Bent Bone Dysplasia-FGFR2 type and adds to the phenotypic spectrum among all FGFR2 disorders. © 2016 Wiley Periodicals, Inc.

Familial Mediterranean fever (FMF), inherited in an autosomal recessive manner, is a systemic auto-inflammatory disorder characterized by recurrent attacks of fever with peritonitis, pleuritis, synovitis and erysipeloid rash. The marenostrin-encoding fever (MEFV) gene, located on chromosome 16p13.3, is the only gene in which mutations are currently known to cause FMF. To correlate specific genotypes with adverse phenotypes of affected populations residing in the Western United States, a retrospective case series review was conducted of all MEFV gene mutation testing completed at UCLA Clinical Molecular Diagnostic Laboratory between February 2002 and February 2012, followed by clinical chart review of all subjects who either have a single or double mutation. All 12 common mutations in the MEFV gene were analyzed and the M694V variant was found to be associated with an adverse FMF clinical outcome in the Armenian-American population, manifested by earlier onset of disease, increased severity of disease, and renal amyloidosis.

Objective Ovarian cysts are the most frequently encountered intra-abdominal masses in females in utero. They may, at times, require perinatal intervention. Using magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US) in prenatal diagnosis, we sought to demonstrate the ability to visualize ovarian cysts on prenatal MRI. Materials and methods This retrospective study included 17 fetal MRI scans from 16 female fetuses (23–37 gestational weeks) with an MRI diagnosis of ovarian cysts after suspicious US findings. A multiplanar MRI protocol was applied to image and to characterize the cysts. The US and MRI findings were compared, and the prenatal findings were compared with postnatal imaging findings or histopathology. Results Simple ovarian cysts were found in 10/16 cases and complex cysts in 7/16 cases, including one case with both. In 11/16 (69%) cases, US and MRI diagnoses were in agreement, and, in 5/16 (31%) cases, MRI specified or expanded the US diagnosis. In 6/16 cases, postnatal US showed that the cysts spontaneously resolved or decreased in size, and in 1/16 cases, postnatal imaging confirmed a hemorrhagic cyst. In 4/16 cases, the prenatal diagnoses were confirmed by surgery/histopathology, and for the rest, postnatal correlation was not available. Conclusion Our results illustrate the MRI visualization of ovarian cysts in utero. In most cases, MRI will confirm the US diagnosis. In certain cases, MRI may provide further diagnostic information, additional to US, which is the standard technique for diagnosis, monitoring, and treatment planning.

Ehlers–Danlos syndrome (EDS) type VIII (periodontitis type) is a distinct form of EDS characterized by periodontal disease leading to precocious dental loss and a spectrum of joint and skin manifestations. EDS type VIII is transmitted in an autosomal dominant pattern; however, the mutated gene has not been identified. There are insufficient data on the spectrum of clinical manifestations and natural history of the disorder, and only a limited number of patients and pedigrees with this condition have been reported. We present a four-generation EDS type VIII kindred and show that EDS VIII is clinically variable and although some cases lack the associated skin and joint manifestations, microscopic evidence of collagen disorganization is detectable. We further propose that the diagnosis of EDS type VIII should be considered in familial forms of periodontitis, even when the associated skin and joint manifestations are unconvincing for the diagnosis of a connective tissue disorder. This novel observation highlights the uncertainty of using connective tissue signs in clinical practice to diagnose EDS type VIII.

Periventricular heterotopia (PH) is a disorder of neuronal migration during fetal development that is characterized by morphologically normal neurons being located in an anatomically abnormal position in the mature brain. PH is usually diagnosed in patients presenting with a seizure disorder, when neuroimaging demonstrates the ectopically placed nodules of neurons. PH is a genetically and phenotypically heterogeneous disorder. The most commonly identified genetic cause is the X-linked dominant inheritance of mutations in the Filamin A (FLNA) gene. Multiple lines of evidence support the contribution of genetic factors in dyslexia. As dyslexia does not show a single-gene pattern of inheritance, it is classified as a complex genetic disorder. We have recently identified a specific reading fluency deficit in a variable group of patients with PH, in the context of normal intelligence. Here, we present a study of a mother-daughter pair who share bilateral widespread gray matter heterotopia caused by a novel mutation in FLNA and the same pattern of X-chromosome inactivation but who exhibit divergent reading and cognitive profiles. This novel observation highlights the uncertainty of using heterotopia anatomy in clinical practice to predict behavioral outcome.

Objective Clubfoot, or talipes equinovarus (TEV), is commonly diagnosed on prenatal ultrasound. This study sought to visualize TEV and associated abnormalities on fetal magnetic resonance imaging (MRI) compared with ultrasound. Methods This retrospective study included the MRI scans of 44 fetuses with TEV using postnatal assessment and autopsy as standard of reference. Isolated TEV was differentiated from complex TEV with associated abnormalities. MRI findings and previous ultrasound diagnoses were compared. Results Isolated TEV was found in 19/44 (43.2%) fetuses and complex TEV in 25/44 (56.8%). Associated abnormalities consisted of the following: central nervous system/spinal abnormalities in 13/25 (52.0%) fetuses; musculoskeletal abnormalities in 7/25 (28.0%); thoracic abnormalities in 3/25 (12.0%); a tumor in one case; and hydrops fetalis in one. Of the 44 cases, 35 (79.5%) pregnancies were delivered, and nine (20.5%) pregnancies, which were terminated, all had complex TEV. Of the 42 available ultrasound reports, additional MRI findings were made in 8/42 (19.0%) cases. MRI did not add findings in isolated TEV on ultrasound. In 4/44 (9.1%) cases, autopsy revealed additional findings compared with prenatal imaging. Conclusion Fetal MRI enables differentiation between isolated and complex TEV. Isolated TEV on ultrasound may not be an MRI indication, whereas MRI may be useful in cases of complex TEV. © 2012 John Wiley & Sons, Ltd.

Objective Previous studies have shown a correlation between hypospadias and intrauterine growth restriction (IUGR), suggesting an association between placental insufficiency and abnormal genital development. This study sought to analyze the association of IUGR and genital abnormalities apparent on fetal magnetic resonance imaging (MRI). Methods This retrospective study included 22 MRI scans of 20 male fetuses between 20 and 35weeks of gestation presenting with IUGR. On MRI, penile length and testicular descent were evaluated. Student’s t-testing and analysis of covariance were used to compare MRI penile length measurements with published normative data obtained from fetal ultrasonography (US) and MRI. McNemar testing was used to evaluate testicular descent in IUGR, compared with reported fetal MRI normative data. Results The penile length in IUGR fetuses was shorter than in normal fetuses (p

Objective Situs anomalies refer to an abnormal organ arrangement, which may be associated with severe errors of development. Due regard being given to prenatal magnetic resonance imaging (MRI) as an adjunct to ultrasonography (US), this study sought to demonstrate the in utero visualization of situs anomalies on MRI, compared to US. Materials and methods This retrospective study included 12 fetuses with situs anomalies depicted on fetal MRI using prenatal US as a comparison modality. With an MRI standard protocol, the whole fetus was assessed for anomalies, with regard to the position and morphology of the following structures: heart; venous drainage and aorta; stomach and intestines; liver and gallbladder; and the presence and number of spleens. Results Situs inversus totalis was found in 3/12 fetuses; situs inversus with levocardia in 1/12 fetuses; situs inversus abdominis in 2/12 fetuses; situs ambiguous with polysplenia in 3/12 fetuses, and with asplenia in 2/12 fetuses; and isolated dextrocardia in 1/12 fetuses. Congenital heart defects (CHDs), vascular anomalies, and intestinal malrotations were the most frequent associated malformations. In 5/12 cases, the US and MRI diagnoses were concordant. Compared to US, in 7/12 cases, additional MRI findings specified the situs anomaly, but CHDs were only partially visualized in six cases. Conclusions Our initial MRI results demonstrate the visualization of situs anomalies and associated malformations in utero , which may provide important information for perinatal management. Using a standard protocol, MRI may identify additional findings, compared to US, which confirm and specify the situs anomaly, but, with limited MRI visualization of fetal CHDs.

Acrodysostosis is a dominantly-inherited, multisystem disorder characterized by skeletal, endocrine, and neurological abnormalities. To identify the molecular basis of acrodysostosis, we performed exome sequencing on five genetically independent cases. Three different missense mutations in PDE4D, which encodes cyclic AMP (cAMP)-specific phosphodiesterase 4D, were found to be heterozygous in three of the cases. Two of the mutations were demonstrated to have occurred de novo, providing strong genetic evidence of causation. Two additional cases were heterozygous for de novo missense mutations in PRKAR1A, which encodes the cAMP-dependent regulatory subunit of protein kinase A and which has been recently reported to be the cause of a form of acrodysostosis resistant to multiple hormones. These findings demonstrate that acrodysostosis is genetically heterogeneous and underscore the exquisite sensitivity of many tissues to alterations in cAMP homeostasis.

To the Editor: Ehlers-Danlos syndrome (EDS) type VIII (OMIM # 130080) is a distinct, largely unrecognized form of EDS characterized primarily by generalized periodontal disease causing progressive loss of the alveolar bone and subsequent dental loss. The associated clinical abnormalities include joint and skin manifestations and with much clinical overlap to other EDS subtypes, mainly the hypermobility and classic types [Stewart et al., 1977; Reinstein et al., 2011; Castori et al., 2010]. A few reported patients had facial characteristics like EDS type IV. The diagnosis of EDS type VIII is established in an individual presenting with dental and connective tissue findings and a typical pattern of inheritance. Previous studies suggest that EDS type VIII is due to dominantly transmitted heterozygous mutations in a yet to be identified gene that is most likely expressed in the periodontal ligament – the tooth supporting matrix – in addition to other connective tissues. Periodontal disease in EDS type VIII seems to be highly penetrant, and can affect young children, which rarely have periodontal disease, even in the presence of poor oral hygiene. Limited data are available on the spectrum of clinical manifestations and natural history of the disorder, resulting in part from the fact that periodontitis and joint hypermobility syndromes are common in the general population [Papapanou, 1999; Khalili, 2008; Biro et al., 1983; Seckin et al., 2005]. Thus, it is likely that individuals with milder clinical manifestations do not come to medical attention and thus go undetected. Musculoskeletal involvement is a frequent finding in hereditary disorders of connective tissue (HDCT). The range of skeletal abnormalities is broad and involves rather benign pectus deformity and pes planus to a more severe expression including progressive scoliosis, contractures, craniosynostosis, recurrent large joint dislocations, and chronic joint instability leading to an early onset degenerative joint disease. There is significant phenotypic variability in EDS type VIII, especially in regard to the skeletal phenotype. Several skeletal phenotypes are known in EDS type VIII, including large and small joint laxity (minimal or significant) and dislocations, Marfanoid habitus, arachnodactyly, chronic joint and limb pain, pectus excavatum, scoliosis, and pes planus [Karrer et al., 2000; Reinstein et al., 2011]. We aimed to explore the skeletal manifestations and complications in a proposita of a previously unreported three generation kindred with EDS type VIII. The patient is a 37-year-old woman who was referred for evaluation of connective tissue disorder. She always had problems with her teeth. Her deciduous teeth appeared at age 1 but soon after turned black and rotten, and all had to be removed before age 18 months. Her permanent teeth appeared at age 7. During her teenage years and in her 20's she underwent numerous dental treatments and extractions, eventually loosing most of her permanent teeth, except for her incisors, in her late 20's. Dental exam and imaging revealed multiple missing teeth and gingival inflammation was severe throughout the mouth. There was moderate periodontitis (class III; with IV being the most severe according to the American Dental Association classification) and radiographic widening of the periodontal ligament space on tooth 27 which was mobile. During the past year, the patient lost the residual incisors and currently wears dentures. She was told that the reason for her dental loss is “soft bone“. The patient reported being very flexible and double jointed from childhood but did not dislocate any joints. During adolescence she developed scoliosis diagnosed through routine exam in high school. She first experienced lower back, hip and knee joint pain in her early 20's; these symptoms have become chronic. At that time, rheumatology workup excluded autoimmune disorders and inflammatory arthritis and she was given pain medications without a specific diagnosis. At age 36 she was first seen by an orthopedist because of increasing left hip pain and imaging studies of the pelvis showed left proximal femur enchondroma which was excised. Since her generalized joint pain had not resolved following surgery, she was further referred for genetic evaluation. Other relevant medical history includes easy bruising with normal healing and normal scar formation. She has myopia and strabismus; a recent echocardiogram was unremarkable. The patient is now experiencing chronic pain in her back, knees, hips and most of her finger joints and is treated with high dose of opiate analgesics. She has a normal body habitus, and soft, doughy but not hyperextensible skin, mild joint laxity was noted although full evaluation for Beighton score was limited because of joint pain triggered by motion. Facial characteristics showed long and narrow nasal bridge with prominent tip; features that have been described before in patients with this type of EDS (Fig.1). Her mother and maternal grandmother have the same medical condition. Her mother, age 58, reports a very similar history with joint laxity for most of her life and dental problems. Currently joint laxity is less pronounced [Beighton score 3], and she is experiencing intermittent back and joint pains. She has osteoporosis diagnosed by bone density scan in her early 40's. She lost all her teeth by age 35 and has worn dentures since than. Facial features are similar to her daughter. The patient's maternal grandmother, currently 82, lost all her teeth by age 20. She has generalized joint pain but has not been under clinical supervision due to lack of insurance. Following establishment of clinical diagnosis of EDS type VIII in this family, radiological evaluation prompted by the proposita's complaints was completed. Figure 1 Facial and dental appearance of family with EDS type VIII. Skeletal survey at the age of 37 years demonstrated multiple abnormal findings in the axial and appendicular skeleton as detailed below. There was moderate scoliosis and radiographically decreased bone density; the latter was confirmed by a dual-emission X-ray absorptiometry (DEXA) study yielding a T score of −2.2 (Fig.2). The sacroiliac joints and hip joints demonstrated no obvious degeneration on conventional radiography. Furthermore, at the right hip, ossicular findings suggested tendinopathy of the gluteal musculature, and at the left hip, there were postsurgical changes of the femoral neck following osteosynthetic treatment of enchondroma (Fig.3). At the right shoulder there was acromio-clavicular joint degeneration, with osteophytic changes and abnormal joint space, also suggesting ligamentous disease. No abnormalities were identified at the left shoulder, the elbow and wrist joints. Radiography and subsequent MR imaging demonstrated distinct osteoarthritis of the right knee joint. Notably, there was marked thinning and damage of the retro-patellar cartilage, as well as in the medial and lateral knee compartments, associated with multiple subchondral cysts and osteophytic changes. At the left knee joint, mild thinning of the cartilaginous surfaces was observed but without further osseous degenerative changes. Joint effusion was present on both sides (Figs.4–5). There were no traumatic or degenerative changes of the collateral and cruciate ligaments of the patellar or quadriceps tendons. Based on an orthopedist evaluation, a joint replacement procedure was suggested to treat right knee joint degeneration. Figure 2 Anterior-posterior and lateral spine radiographs. Figure 3 Pelvic radiographs. Anterior-posterior radiograph of the pelvis. Figure 4 MR imaging of the knee joints. Figure 5 Coronal MR imaging of the right knee joint. We show here the radiological manifestations of early-onset osteoarthritis and reduced bone density that can be associated with EDS type VIII. Although prevalent in middle-age and older adults [affecting 10% of individuals over the age of 50 years and up to 70% of the population over the age of 65 years], osteoarthritis is not a common finding in younger individuals unless resulting from mechanical loading/overuse [Karachalios et al., 2004]. The natural history and skeletal complications associated with EDS VIII are understudied, mainly because of the complexity in patient diagnosis; recruitment and long term follow up. While chronic joint pain and scoliosis have been reported in a recent study of an EDS type VIII family, those manifestations have not been documented radiologically but were rather based on patients description [Reinstein et al., 2011]. Although considerable childhood joint hypermobility was reported by the family reported here, progressive joint stiffness made it less noticeable at the time of examination. These observations highlight the importance of screening for early skeletal manifestations in patients with EDS type VIII, as the symptoms and the radiological abnormalities can present years before the patient comes to medical attention and a correct diagnosis is made. A suggested clinical follow-up would consist of spinal surveillance for scoliosis, imaging studies for joint pain, and DEXA bone density scan followed by proper treatment when indicated. In conclusion, this report supports and extends previous research showing that EDS type VIII can be associated with early-onset degenerative joint disease and reduced bone density, as observed in some other EDS forms. Thus, it implies that clinical surveillance for those complications is warranted. Further detailed clinical studies in larger cohorts of EDS type VIII patients are needed to better delineate the skeletal phenotypic spectrum, and allow optimized clinical follow-up.

Magnetic resonance imaging (MRI) appears to be increasingly used, in addition to standard ultrasonography for the diagnosis of abnormalities in utero. Previous studies have recently drawn attention to the technical refinement of MRI to visualize the fetal bones and muscles. Beyond commonly used T2-weighted MRI, echoplanar, thick-slab T2-weighted and dynamic sequences, and three-dimensional MRI techniques, are about to provide new imaging insights into the normal and the pathological musculoskeletal system of the fetus. This review emphasizes the potential significance of MRI in the visualization of the fetal musculoskeletal system. © 2012 John Wiley & Sons, Ltd.

Objective In view of the implementation of magnetic resonance imaging (MRI) as an adjunct to ultrasonography in prenatal diagnosis, this study sought to demonstrate normal penile growth on prenatal MRI. Methods This was a retrospective study of MRI of 194 male fetuses (18–34 weeks' gestation) with normal anatomy or minor abnormalities. On sagittal T2-weighted MRI sequences, we measured penile length from the glans tip to the scrotal edge (outer length) and from the glans tip to the symphyseal border (total length). Descriptive statistics, as well as correlation and regression analysis, were used to evaluate penile length in relation to gestation. T-tests were calculated to compare mean outer/total length on MRI with published ultrasound data. Results Mean length values, including 95% CIs and percentiles, were defined. Penile length as a function of gestational age was expressed by the following regression equations: outer mean length = − 5.514 + 0.622 × gestational age in weeks; total mean length = − 8.865 + 1.312× gestational age in weeks. The correlation coefficients, r = 0.532 and r = 0.751, respectively, were statistically significant (P < 0.001). Comparison of outer penile length on MRI with published ultrasound penile length data showed no significant differences, while total penile length on MRI was significantly greater than ultrasound penile length (P < 0.001). Conclusion Our MRI results provide a reference range of fetal penile length, which, in addition to ultrasonography, may be helpful in the identification of genital anomalies. Outer penile length on MRI is equivalent to penile length measured on ultrasound, whereas total length is significantly greater. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.

Spondyloepimetaphyseal dysplasia with joint laxity, leptodactylic type (lepto-SEMDJL, aka SEMDJL, Hall type), is an autosomal dominant skeletal disorder that, in spite of being relatively common among skeletal dysplasias, has eluded molecular elucidation so far. We used whole-exome sequencing of five unrelated individuals with lepto-SEMDJL to identify mutations in KIF22 as the cause of this skeletal condition. Missense mutations affecting one of two adjacent amino acids in the motor domain of KIF22 were present in 20 familial cases from eight families and in 12 other sporadic cases. The skeletal and connective tissue phenotype produced by these specific mutations point to functions of KIF22 beyond those previously ascribed functions involving chromosome segregation. Although we have found Kif22 to be strongly upregulated at the growth plate, the precise pathogenetic mechanisms remain to be elucidated.

Objective To visualize in utero male fetal testicular descent on magnetic resonance imaging (MRI) and to correlate it with gestational age. Methods This retrospective study included 202 MRI examination results of 199 male fetuses (17–39 gestational weeks) with normal anatomy or minor congenital abnormalities, following suspicion of anomalies on prenatal ultrasound examination. Using a 1.5-Tesla unit, multiplanar T2-weighted sequences were applied using a standard protocol to image and identify the scrotal content. The relative frequencies of unilateral and bilateral testicular descent were calculated and correlated with gestational age. Results Between 17 and 25 gestational weeks, neither unilateral nor bilateral testicular descent was visualized on MRI. Testicular descent was first observed at 25 + 4 weeks, in 7.7% of cases. 12.5% of 27-week fetuses showed unilateral descent and 50% showed bilateral descent. Bilateral descent was observed in 95.7% of cases, on average, from 30 to 39 weeks. Conclusions Our results chart the time course of testicular descent on prenatal MRI, which may be helpful in the identification of normal male sexual development and in the diagnosis of congenital abnormalities, including the early detection of cryptorchidism. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.

Objective In view of the increasing use of fetal magnetic resonance imaging (MRI) as an adjunct to prenatal ultrasonography, we sought to demonstrate the visualization of upper extremity abnormalities and associated defects on MRI, with regard to fetal outcomes and compared with ultrasound imaging. Methods This retrospective study included 29 fetuses with upper extremity abnormalities visualized with fetal MRI following suspicious ultrasound findings and confirmed by postnatal assessment or autopsy. On a 1.5-Tesla unit, dedicated sequences were applied to image the extremities. Central nervous system (CNS) and extra-CNS anomalies were assessed to define extremity abnormalities as isolated or as complex, with associated defects. Fetal outcome was identified from medical records. MRI and ultrasound findings, when available, were compared. Results Isolated upper extremity abnormalities were found in three (10.3%) fetuses. In 26 (89.7%) fetuses complex abnormalities, including postural extremity disorders (21/26) and structural extremity abnormalities (15/26), were demonstrated. Associated defects involved: face (15/26); musculoskeletal system (14/26); thorax and cardio/pulmonary system (12/26); lower extremities (12/26); brain and skull (10/26); and abdomen (8/26). Of the 29 cases, 18 (62.1%) pregnancies were delivered and 11 (37.9%) were terminated. MRI and US findings were compared in 27/29 cases: the diagnosis was concordant in 14 (51.9%) of these cases, and additional findings were made on MRI in 13/27 (48.1%) cases. Conclusions Visualization of upper extremity abnormalities on fetal MRI enables differentiation between isolated defects and complex ones, which may be related to poor fetal prognosis. MRI generally confirms the ultrasound diagnosis, and may provide additional findings in certain cases. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.

Genetic disorders involving the skeletal system arise through disturbances in the complex processes of skeletal development, growth and homeostasis and remain a diagnostic challenge because of their variety. The Nosology and Classification of Genetic Skeletal Disorders provides an overview of recognized diagnostic entities and groups them by clinical and radiographic features and molecular pathogenesis. The aim is to provide the Genetics, Pediatrics and Radiology community with a list of recognized genetic skeletal disorders that can be of help in the diagnosis of individual cases, in the delineation of novel disorders, and in building bridges between clinicians and scientists interested in skeletal biology. In the 2010 revision, 456 conditions were included and placed in 40 groups defined by molecular, biochemical, and/or radiographic criteria. Of these conditions, 316 were associated with mutations in one or more of 226 different genes, ranging from common, recurrent mutations to “private” found in single families or individuals. Thus, the Nosology is a hybrid between a list of clinically defined disorders, waiting for molecular clarification, and an annotated database documenting the phenotypic spectrum produced by mutations in a given gene. The Nosology should be useful for the diagnosis of patients with genetic skeletal diseases, particularly in view of the information flood expected with the novel sequencing technologies; in the delineation of clinical entities and novel disorders, by providing an overview of established nosologic entities; and for scientists looking for the clinical correlates of genes, proteins and pathways involved in skeletal biology. © 2011 Wiley-Liss, Inc.

Objective In view of the increasing role of magnetic resonance imaging (MRI) as an adjunct to prenatal ultrasonography (US), this study sought to demonstrate the visualization of fetal akinesia and associated abnormalities on MRI. Methods This retrospective study included six fetuses with akinesia and associated abnormalities, depicted on fetal MRI after suspicious prenatal US. The whole fetus was assessed for musculoskeletal abnormalities and associated pathological conditions elsewhere. Fetal outcome data were compared with prenatal imaging. US and MRI findings were also compared. Results Akinesia resulting in arthrogryposis was seen in 6/6 fetuses, with abnormal musculature in 5/6 fetuses. Associated brain abnormalities were found in 2/6 fetuses; facial abnormalities in 3/6; lung hypoplasia in 3/6; and polyhydramnios in 2/6. There were 5/6 pregnancies that were terminated and one individual died neonatally. MRI and brain autopsy were concordant in 4/6 cases. MRI and body autopsy were concordant in 1/6 cases and in 5/6 cases, autopsy revealed additional abnormalities. In addition to US, MRI correctly identified central nervous system findings in four cases and lung hypoplasia in three cases. Conclusion Our MRI results demonstrate fetal akinesia and associated abnormalities, which may have an impact on perinatal management, as an adjunct to prenatal US. Copyright  2011 John Wiley & Sons, Ltd. Supporting information may be found in the online version of this article.

Diaphanospondylodysostosis (DSD) is a rare, recessively inherited, perinatal lethal skeletal disorder. The low frequency and perinatal lethality of DSD makes assembling a large set of families for traditional linkage-based genetic approaches challenging. By searching for evidence of unknown ancestral consanguinity, we identified two autozygous intervals, comprising 34 Mbps, unique to a single case of DSD. Empirically testing for ancestral consanguinity was effective in localizing the causative variant, thereby reducing the genomic space within which the mutation resides. High-throughput sequence analysis of exons captured from these intervals demonstrated that the affected individual was homozygous for a null mutation in BMPER, which encodes the bone morphogenetic protein-binding endothelial cell precursor-derived regulator. Mutations in BMPER were subsequently found in three additional DSD cases, confirming that defects in BMPER produce DSD. Phenotypic similarities between DSD and Bmper null mice indicate that BMPER-mediated signaling plays an essential role in vertebral segmentation early in human development.

The skeletal dysplasias (osteochondrodysplasias) are a heterogeneous group of more than 350 disorders frequently associated with orthopedic complications and varying degrees of dwarfism or short stature. These disorders are diagnosed based on radiographic, clinical, and molecular criteria. The molecular mechanisms have been elucidated in many of these disorders providing for improved clinical diagnosis and reproductive choices for affected individuals and their families. An increasing variety of medical and surgical treatment options can be offered to affected individuals to try to improve their quality of life and lifespan.

Cleidocranial dysplasia (CCD) is a rare autosomal dominant skeletal dysplasia due to mutations causing haploinsufficiency of RUNX2, an osteoblast transcription factor specific for bone and cartilage. The classic form of CCD is characterized by delayed closure of the fontanels, hypoplastic or aplastic clavicles and dental anomalies. Clinical reports suggest that a subset of patients with CCD have skeletal changes which mimic hypophosphatasia. Mutations in RUNX2 are detected in approximately 65% of cases of CCD, and microdeletions occur in 13%. We present clinical and radiological features in a 6-year-old child with severe CCD manifested by absence of the clavicles marked calvarial hypomineralization, osteoporosis and progressive kyphoscoliosis. Hypophosphatasia features included Bowdler spurs, severe osteopenia and low alkaline phosphatase. Following negative mutation analysis of RUNX2, comparative genomic hybridization (CGH) microarray was performed. The result revealed a microdeletion in RUNX2, disrupting the C-terminal part of the gene.

Treatment of patients with Hutchinson-Gilford progeria syndrome (HGPS) is based on the abnormalities of accelerated aging that affect the healing processes, combined with a fragile cardiovascular status. A classic HGPS case, of Korean ancestry, previously treated for severe coxa valga with bilateral varus osteotomies using blade plate fixation is presented. Complications over the blade plate area required removal of the hardware, after which the patient showed right-sided hypertonicity--determined to be a cerebrovascular accident. Subsequently, the patient returned almost completely to her presurgical neurologic status. Perioperative planning for HGPS patients should include risks that are typically considered in the planning for geriatric patient care.

The osteochondrodysplasias, or skeletal dysplasias are a genetically heterogeneous group of over 350 distinct disorders, and many of them can present in the prenatal period as demonstrated by ultrasound. Differentiating these disorders in the prenatal period can be challenging because they are rare and many of the ultrasound findings are not necessarily pathognomic for a specific disorder. However, differentiating known lethal disorders from nonlethal disorders, providing differential diagnoses before delivery, determining postdelivery management plans and ultimately determining accurate recurrences risks to the at-risk couples improves patient care. These guidelines provide an approach to a fetus suspected of manifesting a skeletal dysplasia.

Analysis of a nuclear family with three affected offspring identified an autosomal-recessive form of spondyloepimetaphyseal dysplasia characterized by severe short stature and a unique constellation of radiographic findings. Homozygosity for a haplotype that was identical by descent between two of the affected individuals identified a locus for the disease gene within a 17.4 Mb interval on chromosome 15, a region containing 296 genes. These genes were assessed and ranked by cartilage selectivity with whole-genome microarray data, revealing only two genes, encoding aggrecan and chondroitin sulfate proteoglycan 4, that were selectively expressed in cartilage. Sequence analysis of aggrecan complementary DNA from an affected individual revealed homozygosity for a missense mutation (c.6799G → A) that predicts a p.D2267N amino acid substitution in the C-type lectin domain within the G3 domain of aggrecan. The D2267 residue is predicted to coordinate binding of a calcium ion, which influences the conformational binding loops of the C-type lectin domain that mediate interactions with tenascins and other extracellular-matrix proteins. Expression of the normal and mutant G3 domains in mammalian cells showed that the mutation created a functional N-glycosylation site but did not adversely affect protein trafficking and secretion. Surface-plasmon-resonance studies showed that the mutation influenced the binding and kinetics of the interactions between the aggrecan G3 domain and tenascin-C. These findings identify an autosomal-recessive skeletal dysplasia and a significant role for the aggrecan C-type lectin domain in regulating endochondral ossification and, thereby, height.

Autosomal dominant osteogenesis imperfecta (OI) is caused by mutations in the genes (COL1A1 or COL1A2) encoding the chains of type I collagen. Recently, dysregulation of hydroxylation of a single proline residue at position 986 of both the triple-helical domains of type I collagen alpha1(I) and type II collagen alpha1(II) chains has been implicated in the pathogenesis of recessive forms of OI. Two proteins, cartilage-associated protein (CRTAP) and prolyl-3-hydroxylase-1 (P3H1, encoded by the LEPRE1 gene) form a complex that performs the hydroxylation and brings the prolyl cis-trans isomerase cyclophilin-B (CYPB) to the unfolded collagen. In our screen of 78 subjects diagnosed with OI type II or III, we identified three probands with mutations in CRTAP and 16 with mutations in LEPRE1. The latter group includes a mutation in patients from the Irish Traveller population, a genetically isolated community with increased incidence of OI. The clinical features resulting from CRTAP or LEPRE1 loss of function mutations were difficult to distinguish at birth. Infants in both groups had multiple fractures, decreased bone modeling (affecting especially the femurs), and extremely low bone mineral density. Interestingly, "popcorn" epiphyses may reflect underlying cartilaginous and bone dysplasia in this form of OI. These results expand the range of CRTAP/LEPRE1 mutations that result in recessive OI and emphasize the importance of distinguishing recurrence of severe OI of recessive inheritance from those that result from parental germline mosaicism for COL1A1 or COL1A2 mutations.

The osteochondrodysplasias or skeletal dysplasias are a heterogenous group of over 350 distinct disorders of skeletogenesis. Many manifest in the prenatal period, making them amenable to ultrasound prenatal diagnosis. A retrospective analysis evaluated 1,500 cases referred to the International Skeletal Dysplasia Registry (ISDR) to determine the relative frequency of specific osteochondrodysplasias and correlation of ultrasound versus radiographic diagnoses for these disorders. Within the retrospective cohort of 1,500 cases, 85% of the referred cases represented well-defined skeletal dysplasias, and the other 15% of cases were a mixture of genetic syndromes and probable early-onset intrauterine growth restriction. The three most common prenatal-onset skeletal dysplasias were osteogenesis imperfecta type 2, thanatophoric dysplasia and achondrogenesis 2, accounting for almost 40% of the cases. In a prospective analysis of 500 cases using a standardized ultrasound approach to the evaluation of these disorders, the relative frequencies of osteogenesis imperfecta type 2, thanatophoric dysplasia and achondrogenesis 2 were similar to the retrospective analysis. This study details the relative frequencies of specific prenatal-onset osteochondrodysplasias, their heterogeneity of prenatal-onset skeletal disorders and provides a standardized prenatal ultrasound approach to these disorders which should aid in the prenatal diagnosis of fetuses suspected of manifesting skeletal dysplasias.

A multilayered patella is a characteristic radiographic finding of recessive multiple epiphyseal dysplasia (rMED) caused by DTDST mutations. However it has been recently reported in a dominant MED case with a COL9A2 mutation. We report on a new radiographic patellar finding in a patient with pseudoachondroplasia and a heterozygous COMP mutation. It is similar to the radiographic appearance of fusing multilayered patellae in rMED cases. This led us to search the International Skeletal Dysplasia Registry for similar abnormalities. We did not observe this finding in other skeletal dysplasias or other pseudoachondroplasia cases. However we found an accessory ossification center of the patella in another pseudoachondroplasia case. Thus, we hypothesize that variable defects of cartilage extracellular matrix can result in similar abnormal patellar ossifications, and emphasize the importance of a lateral knee radiograph in patients with the pseudoachondroplasia-MED bone dysplasia group of disorders.

The brachyolmias constitute a clinically and genetically heterogeneous group of skeletal dysplasias characterized by a short trunk, scoliosis and mild short stature(1). Here, we identify a locus for an autosomal dominant form of brachyolmia on chromosome 12q24.1-12q24.2. Among the genes in the genetic interval, we selected TRPV4, which encodes a calcium permeable cation channel of the transient receptor potential (TRP) vanilloid family, as a candidate gene because of its cartilage-selective gene expression pattern. In two families with the phenotype, we identified point mutations in TRPV4 that encoded R616Q and V620I substitutions, respectively. Patch clamp studies of transfected HEK cells showed that both mutations resulted in a dramatic gain of function characterized by increased constitutive activity and elevated channel activation by either mechano-stimulation or agonist stimulation by arachidonic acid or the TRPV4-specific agonist 4 alpha-phorbol 12,13-didecanoate (4 alpha PDD). This study thus defines a previously unknown mechanism, activation of a calcium-permeable TRP ion channel, in skeletal dysplasia pathogenesis. ispartof: Nature Genetics vol:40 issue:8 pages:999-1003 ispartof: location:United States status: published

Proteoglycans are a family of extracellular macromolecules comprised of glycosaminoglycan chains of a repeated disaccharide linked to a central core protein1,2. Proteoglycans have critical roles in chondrogenesis and skeletal development. The glycosaminoglycan chains found in cartilage proteoglycans are primarily composed of chondroitin sulfate3. The integrity of chondroitin sulfate chains is important to cartilage proteoglycan function; however, chondroitin sulfate metabolism in mammals remains poorly understood. The solute carrier-35 D1 (SLC35D1) gene (SLC35D1) encodes an endoplasmic reticulum nucleotide-sugar transporter (NST) that might transport substrates needed for chondroitin sulfate biosynthesis4,5. Here we created Slc35d1-deficient mice that develop a lethal form of skeletal dysplasia with severe shortening of limbs and facial structures. Epiphyseal cartilage in homozygous mutant mice showed a decreased proliferating zone with round chondrocytes, scarce matrices and reduced proteoglycan aggregates. These mice had short, sparse chondroitin sulfate chains caused by a defect in chondroitin sulfate biosynthesis. We also identified that loss-of-function mutations in human SLC35D1 cause Schneckenbecken dysplasia, a severe skeletal dysplasia. Our findings highlight the crucial role of NSTs in proteoglycan function and cartilage metabolism, thus revealing a new paradigm for skeletal disease and glycobiology.

Angulated or bent femur (isolated or associated with other long bone bowing) in the fetus or newborn is relatively common when evaluating patients with skeletal dysplasias. To determine the extent and heterogeneity of disorders associated with angulated or bent femurs, we analyzed cases in the radiographic database (1998-2006) of the International Skeletal Dysplasia Registry (ISDR) and determined which established skeletal dysplasias and genetic syndromes are associated with this finding. The results show that more than 40 distinct disorders with varying frequency (very rare to more commonly occurring disorders) can be associated with bowed/bent/angulated femurs. Sixty-six percent of the cases with angulated femurs belonged to three well described groups of disorders; campomelic disorders (24.4%), thanatophoric dysplasia (23.9%) and osteogenesis imperfecta (OI) (18.1%). With specific emphasis on these, this cross-sectional cohort provides discussion of data on other rare disorders associated with angulated femurs and the importance of the finding relative to its occurrence within a diagnostic group. This study aims to provide differential diagnosis of entities to be considered when a fetus or newborn is found to have congenital bowing/angulation of the femur.

The filamins are a family of cytoplasmic proteins that bind to and organize actin filaments, link membrane proteins to the cytoskeleton, and provide a scaffold for signaling molecules. Mutations in the gene encoding filamin B (FLNB) cause a spectrum of osteochondrodysplasias, including atelosteogenesis type I (AOI) and atelosteogenesis type III (AOIII). AOI and AOIII are autosomal dominant lethal skeletal dysplasias characterized by overlapping clinical findings that include vertebral abnormalities, disharmonious skeletal maturation, hypoplastic long bones, and joint dislocations. Previous studies have shown that heterozygosity for missense mutations that alter the CH2 domain and repeat 6 region of filamin B produce AOI and AOIII. In this study, 14 novel missense mutations in FLNB were found in 15 unrelated patients with AOI and AOIII. The majority of the mutations resided in exon 2 and exon 3, which encode the CH2 domain of the actin,binding region of filamin B. The remaining mutations were found in exon 28 and exon 29, which encode repeats 14 and 15 of filamin B. These results show that clustering of mutations in two regions of FLNB produce AOI/AOIII, and highlight the important role of this cytoskeletal protein in normal skeletogenesis. Hum Mutat 27(7), 705-710,2006. Published 2006 Wiley,Liss, Inc.(dagger).

Pachydermoperiostosis (PDP) is a rare genodermatosis, characterized by pachydermia, digital clubbing, periostosis and an excess of affected males. Although an autosomal dominant model with incomplete penetrance and variable expression has been proved, both autosomal recessive and X-linked inheritance have been suggested. However, at present, genetic heterogeneity is not fully supported. The aim of this study is to review the clinical and pedigree data of 68 published PDP families, including 204 patients. This analysis has confirmed an autosomal dominant mutation in 37 families and suggested the existence of an autosomal recessive form in the remaining families. The two forms may differ in clinical severity, intrafamilial variability and prevalence of some features. Additionally, the marked skewed sex ratio could not be easily explained by an X-linked mutation, but alternative explanations (i.e. testosterone promoting proliferation) are discussed.

Medical genetics emerged from a basic science only one half century ago. Scientists and physicians housed in a variety of basic science and clinical departments have accomplished many of the major advances in the study of genetic diseases in children. A scientific approach to human genetics emerged in 1948 with the establishment of the American Society of Human Genetics. Even before the use of modern laboratory techniques, Pediatric departments spearheaded the clinical description of simple genetic disorders, syndromes, and major malformations. The burgeoning of medical genetics as a specialty and its tremendous growth in departments of pediatrics was stimulated by major technological advances, such as the ability to visualize human chromosomes, the development of methods to study biochemical variations in blood and urine, cell culture, somatic cell hybridization, and molecular technology, all of which allowed for the diagnosis, treatment, and prevention of genetic disorders in children. Many pediatricians sought training in genetics, and training programs in medical genetics flourished in departments of pediatrics. The explosion of knowledge concerning the metabolic and molecular causes of genetic disease and understanding of their pathogenesis has led to a variety of specific diagnostic, preventive, and therapeutic approaches for alleviating the symptoms or preventing the complications of many of these disorders. Medical genetics is now recognized as a distinct medical specialty with its own American Board of Medical Specialties approved board (American Board of Medical Genetics) and clinical specialty college (American College of Medical Genetics).

Objective Recognition of prenatal-onset skeletal dysplasias has improved with advances in ultrasound imaging. Skeletal abnormalities can be recognized by two-dimensional (2D) ultrasound, but generating a precise diagnosis can be challenging. We aimed to determine whether three-dimensional (3D) imaging conferred any advantages over 2D imaging in these cases. Methods We studied five women with fetuses of 16–28 gestational weeks referred for abnormal ultrasound skeletal findings. First 2D and then 3D sonography was performed and the results compared. Results The pregnancies resulted in the following skeletal dysplasias: thanatophoric dysplasia, achondrogenesis II/hypochondrogenesis, achondroplasia, chondrodysplasia punctata (rhizomelic form) and Apert's syndrome. For all five fetuses, the correct diagnosis was made in the prenatal period by analysis of the 2D images. In each case the 3D images confirmed the preliminary diagnosis and for many findings it improved the visualization of the abnormalities. Conclusion The 3D imaging had advantages over the 2D imaging when it came to evaluation of facial dysmorphism, relative proportion of the appendicular skeletal elements and the hands and feet. Most importantly, the patient and referring physician appreciated the 3D images of the abnormal findings more readily which aided in counseling and management of the pregnancy. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.

Dolichospondylic dysplasia (DD) is a rare skeletal dysplasia primarily characterized by tall vertebral bodies and disproportionate short stature. Radiographic manifestations include tall vertebral bodies and gracile bones of the hands. Patients usually have eye and ear findings in addition to borderline mental retardation; however, tall vertebral bodies and slender tubular bones are also seen in the 3-M syndrome. Patients with the 3-M syndrome have a characteristic face with a triangular shape, frontal bossing, a flattened malar region, full eyebrows, a short nose with a bulbous tip, upturned nares, and full lips. We present two unrelated patients who share a distinct phenotype and have tall vertebral bodies, overtubulation of long bones, and short tubular bones of the hands and feet. We discuss the overlapping and distinguishing features between DD and the 3-M syndrome. Patient 1 was a 13-year-old female, and patient 2 was an unrelated adult female. These patients had normocephaly and short stature. They shared a common phenotype consisting of mild malar hypoplasia, a narrowed nasal body with a fleshy tip, full lips, and normal intelligence. In addition, they showed mild hand and foot abnormalities. These two patients lack many of the typical clinical features of both DD and the 3-M syndrome. They share a common phenotype and likely represent a distinct disorder. The spectrum of disorders with tall vertebral bodies as a key feature may include different entities that may be further defined with the characterization of the molecular defect(s).

Smith-McCort dysplasia is a rare autosomal recessive osteochondrodysplasia characterized by short limbs and a short trunk with a barrel-shaped chest. The radiographic phenotype includes platyspondyly, generalized abnormalities of the epiphyses and metaphyses, and a distinctive lacy appearance of the iliac crest. We performed a genomewide scan in a consanguineous family from Guam and found evidence of linkage to loci on chromosome 18q12. Analysis of a second, smaller family was also consistent with linkage to this region, producing a maximum combined two-point LOD score of 3.04 at a recombination fraction of 0 for the marker at locus D18S450. A 10.7-cM region containing the disease gene was defined by recombination events in two affected individuals in the larger family. Furthermore, all affected children in the larger family were homozygous for a subset of marker loci within this region, defining a 1.5-cM interval likely to contain the defective gene. Analysis of three small, unrelated families with Dyggve-Melchior-Clausen syndrome, a radiographically identical disorder with the additional clinical finding of mental retardation, provided evidence of linkage to the same region, a result consistent with the hypothesis that the two disorders are allelic.

Two patients with Marinesco-Sjogren syndrome had striking orthopaedic abnormalities that seemed to arise from multiple areas of physeal growth arrest. Major involvement was seen in the distal femora, where bilateral hypoplasia of the lateral condyles resulted in progressive valgus, patellar dislocation, and quadriceps dysfunction. Marinesco-Sjogren syndrome seems to arise from an error in lysosomal handling of lipids. Timely orthopaedic intervention may be helpful in prolonging ambulation in these patients.

Genetic disorders of the skeleton (skeletal dysplasias and dysostoses) are a large and disparate group of diseases whose unifying features are malformation, disproportionate growth, and deformation of the skeleton or of individual bones or groups of bones. To cope with the large number of different disorders, the “Nosology and Classification of the Osteochondrodysplasias,” based on clinical and radiographic features, has been designed and revised periodically. Biochemical and molecular features have been partially implemented in the Nosology, but the rapid accumulation of knowledge on genes and proteins cannot be easily merged into the clinical–radiographic classification. We present here, as a complement to the existing Nosology, a classification of genetic disorders of the skeleton based on the structure and function of the causative genes and proteins. This molecular–pathogenetic classification should be helpful in recognizing metabolic and signaling pathways relevant to skeletal development, in pointing out candidate genes and possible therapeutic targets, and more generally in bringing the clinic closer to the basic science laboratory and in promoting research in this field. © 2002 Wiley-Liss, Inc.

The X-linked form of spondyloepiphyseal dysplasia tarda (SEDL), a radiologically distinct skeletal dysplasia affecting the vertebrae and epiphyses, is caused by mutations in the SEDL gene. To characterize the molecular basis for SEDL, we have identified the spectrum of SEDL mutations in 30 of 36 unrelated cases of X-linked SEDL ascertained from different ethnic populations. Twenty-one different disease-associated mutations now have been identified throughout the SEDL gene. These include nonsense mutations in exons 4 and 5, missense mutations in exons 4 and 6, small (2–7 bp) and large (>1 kb) deletions, insertions, and putative splicing errors, with one splicing error due to a complex deletion/insertion mutation. Eight different frameshift mutations lead to a premature termination of translation and account for >43% (13/30) of SEDL cases, with half of these (7/13) being due to dinucleotide deletions. Altogether, deletions account for 57% (17/30) of all known SEDL mutations. Four recurrent mutations (IVS3+5G→A, 157–158delAT, 191–192delTG, and 271–275delCAAGA) account for 43% (13/30) of confirmed SEDL cases. The results of haplotype analyses and the diverse ethnic origins of patients support recurrent mutations. Two patients with large deletions of SEDL exons were found, one with childhood onset of painful complications, the other relatively free of additional symptoms. However, we could not establish a clear genotype/phenotype correlation and therefore conclude that the complete unaltered SEDL-gene product is essential for normal bone growth. Molecular diagnosis can now be offered for presymptomatic testing of this disorder. Appropriate lifestyle decisions and, eventually, perhaps, specific SEDL therapies may ameliorate the prognosis of premature osteoarthritis and the need for hip arthroplasty.

Pseudoachondroplasia (PSACH) and spondyloepiphyseal dysplasia congenita (SEDC) are autosomal dominant forms of short-limb short stature caused by mutations in genes that encode structural components of the cartilage extracellular matrix. PSACH results from mutations in the cartilage oligomeric matrix protein (COMP) gene, while SEDC is caused by mutations in the gene for type II procollagen (COL2A1). We report a child with a distinct skeletal dysplasia due to the combined phenotypes of PSACH and SEDC. The proband's mother had PSACH and his father had SEDC. The child was suspected of having both phenotypes on the basis of the severity of his clinical and radiographic findings, and this was confirmed by molecular analysis. The COMP gene mutation (C348R), while not previously published, is typical of those in PSACH patients, whereas the COL2A1 mutation (T1370M) is somewhat atypical, as it predicts an amino acid change within the carboxyl-terminal region of the protein. Both mutations segregated with their respective phenotypes within this family. The description and natural history of the double heterozygote phenotype may be useful in counseling families regarding risk and prognosis.