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Proximal spinal muscular atrophy (SMA), a leading genetic cause of infant death worldwide, is an early-onset motor neuron disease characterized by loss of α-motor neurons and associated muscle atrophy. SMA is caused by deletion or other disabling mutations of survival motor neuron 1 (SMN1) but retention of one or more copies of the paralog SMN2. Within the SMA population, there is substantial variation in SMN2 copy number (CN); in general, those individuals with SMA who have a high SMN2 CN have a milder disease. Because SMN2 functions as a disease modifier, its accurate CN determination may have clinical relevance. In this study, we describe the development of array digital PCR (dPCR) to quantify SMN1 and SMN2 CNs in DNA samples using probes that can distinguish the single nucleotide difference between SMN1 and SMN2 in exon 8. This set of dPCR assays can accurately and reliably measure the number of SMN1 and SMN2 copies in DNA samples. In a cohort of SMA patient-derived cell lines, the assay confirmed a strong inverse correlation between SMN2 CN and disease severity. We can detect SMN1-SMN2 gene conversion events in DNA samples by comparing CNs at exon 7 and exon 8. Partial deletions of SMN1 can also be detected with dPCR by comparing CNs at exon 7 or exon 8 with those at intron 1. Array dPCR is a practical technique to determine, accurately and reliably, SMN1 and SMN2 CNs from SMA samples as well as identify gene conversion events and partial deletions of SMN1.

Specific activating missense HRAS variants cause Costello syndrome (CS), a RASopathy with recognizable facial features. The majority of these dominant disease causing variants affect the glycine residues in position 12 or 13. A clinically suspected CS diagnosis can be confirmed through identification of a dominant pathogenic HRAS variant. A novel HRAS variant predicting p.(Glu62_Arg68dup) was identified in an individual with hypertrophic cardiomyopathy, Chiari 1 malformation and ectodermal findings consistent with a RASopathy. Functional studies showed that the p.Glu62_Arg68dup alteration affects HRAS interaction with effector protein PIK3CA (catalytic subunit of phosphoinositide 3-kinase) and the regulator neurofibromin 1 (NF1) GTPase-activating protein (GAP). HRAS Glu62_Arg68dup binding with effectors rapidly accelerated fibrosarcoma (RAF1), RAL guanine nucleotide dissociation stimulator (RALGDS) and phospholipase C1 (PLCE1) was enhanced. Accordingly, p.Glu62_Arg68dup increased steady-state phosphorylation of MEK1/2 and ERK1/2 downstream of RAF1, whereas AKT phosphorylation downstream of PI3K was not significantly affected. Growth factor stimulation revealed that expression of HRAS Glu62_Arg68dup abolished the HRAS' capacity to modulate downstream signaling. Our data underscore that different qualities of dysregulated HRAS-dependent signaling dynamics determine the clinical severity in CS.

Costello syndrome (CS) is an autosomal-dominant condition caused by activating missense mutations in HRAS. There is little literature describing health concerns specific to adults with CS. Parents of individuals with CS need to know what to anticipate as their children age. We surveyed a group of 20 adults and older adolescents with CS regarding their medical concerns and lifestyle characteristics. We identified several previously undescribed actionable medical concerns in adults with CS. First, the high prevalence of anxiety in this cohort indicates that screening for anxiety is warranted since this is a treatable condition that can have a significant impact on quality of life. Second, adults with CS should be monitored for progressive contractures or other problems that could decrease mobility. This is especially important in a population that seems to have increased risk for osteopenia. Finally, the lack of cancer diagnoses in adulthood is of interest, although the cohort is too small to draw definitive conclusions about cancer risk in adults with CS. Ongoing follow-up of the current cohort of adults with CS is necessary to delineate progressive medical and physical problems, which is essential for providing targeted management recommendations and anticipatory guidance to families., (© 2019 Wiley Periodicals, Inc.)

Costello syndrome is part of the RASopathies, a group of neurocardiofaciocutaneous syndromes caused by deregulation of the RAS mitogen-activated protein kinase pathway. Heterozygous mutations in HRAS are responsible for Costello syndrome, with more than 80% of the patients harboring the specific p.Gly12Ser variant. These individuals show a homogeneous phenotype. The clinical characteristics of the Costello syndrome individuals harboring rarer HRAS mutations are less understood, due to the small number of reported cases. Here, we describe the phenotypic spectrum of five additional individuals with HRAS c.38G>A; p.Gly13Asp, including one with somatic mosaicism, and review five previously described cases. The facial and hair abnormalities of the HRAS p.Gly13Asp individuals differ from the typical pattern observed in those showing the common HRAS (p.Gly12Ser) mutation, with less coarse facial features and slow growing, sparse hair with abnormal texture, the latter resembling the pattern observed in Noonan syndrome-like disorder with loose anagen hair and individuals harboring another amino acid substitution in HRAS (p.Gly13Cys). Although some individuals with HRAS p.Gly13Asp developed papillomata and vascular proliferation lesions, no malignant tumors occurred, similar to what was reported for individuals harboring the HRAS p.Gly13Cys. The fact that no malignant tumors were described in these individuals does not allow definitive conclusions about the risk for cancer development. It remains to be determined if substitutions of amino acid 13 in HRAS (p.Gly13Asp and p.Gly13Cys) increase the risk of tumor development., (© 2017 Wiley Periodicals, Inc.)

Fibroblasts and lymphoblastoid cell lines (LCLs) derived from individuals with spinal muscular atrophy (SMA) have been and continue to be essential for translational SMA research. Authentication of cell lines helps ensure reproducibility and rigor in biomedical research. This quality control measure identifies mislabeling or cross-contamination of cell lines and prevents misinterpretation of data. Unfortunately, authentication of SMA cell lines used in various studies has not been possible because of a lack of a reference. In this study, we provide said reference so that SMA cell lines can be subsequently authenticated. We use short tandem repeat (STR) profiling and digital PCR (dPCR), which quantifies SMN1 and SMN2 copy numbers, to generate molecular identity codes for fibroblasts and LCLs that are commonly used in SMA research. Using these molecular identity codes, we clarify the familial relationships within a set of fibroblasts commonly used in SMA research. This study presents the first cell line reference set for the SMA research community and demonstrates its usefulness for re-identification and authentication of lines commonly used as in vitro models for future studies., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Dysregulation of the mitogen activated protein kinase (MAPK) pathway in Costello syndrome (CS) may contribute to increased risk for autism-spectrum disorder (ASD). We examined prevalence of ASD symptoms in 14 individuals (six females) age 1-18 years with molecularly confirmed CS. Caregivers completed the Modified Checklist for Autism in Toddlers (M-CHAT) for ages 0-4 years (n = 7), and the Social Communication Questionnaire (SCQ) for ages 4 and older (n = 7). Age was associated with meeting ASD criteria: 5/7 (71.4%) younger children met the ASD cut-off on the MCHAT, compared to 0/7 older children on the SCQ. The following medical and developmental factors were strongly associated with ASD criteria on the M-CHAT: having a gastrostomy tube at time of assessment, not eating solid food, not walking, and not being toilet trained. Two children who met stricter ASD criteria had significantly lower adaptive functioning and were physically much more impaired. Among older participants, SCQ subscale scores in communication, socialization, and repetitive behavior domains were comparable to the typically-developing normative sample. ASD symptoms were highly elevated in younger CS individuals. Older children did not differ from typically developing samples in prevalence of ASD symptoms. CS individuals may appear to fall on the autism spectrum in early childhood due to severe feeding and orthopedic problems that improve by age four, suggesting many of these children may eventually emerge out of an ASD presentation., (© 2017 Wiley Periodicals, Inc.)

Costello syndrome (CS) patients suffer from a very high 10% incidence of embryonal rhabdomyosarcoma (ERMS). As tools to discover targeted therapeutic leads, we used a CS patient-derived ERMS cell line (CS242 ERMS) harboring a homozygous p.G12A mutation in HRAS , and a control cell line derived from the same patient comprising non-malignant CS242 fibroblasts with a heterozygous p.G12A HRAS mutation. A library of 2,000 compounds with known pharmacological activities was screened for their effect on CS242 ERMS cell viability. Follow-up testing in a panel of cell lines revealed that various compounds originally developed for other indications were remarkably selective; notably, the phosphodiesterase (PDE) inhibitor zardaverine was at least 1,000-fold more potent in CS242 ERMS than in the patient-matched non-malignant CS242 fibroblasts, other ERMS, or normal fibroblasts. Chronic treatment with zardaverine led to the emergence of resistant cells, consistent with CS242 ERMS comprising a mixed population of cells. Many PDE inhibitors in addition to zardaverine were tested on CS242 ERMS, but almost all had no effect. Interestingly, zardaverine and analogs showed a similar cytotoxicity profile in CS242 ERMS and cervical carcinoma-derived HeLa cells, suggesting a mechanism of action common to both cell types that does not require the presence of an HRAS mutation (HeLa contains wild type HRAS ). Two recent studies presented possible mechanistic explanations for the cytotoxicity of zardaverine in HeLa cells. One revealed that zardaverine inhibited a HeLa cell-based screen measuring glucocorticoid receptor (GR) activation; however, using engineered HeLa cells, we ruled out a specific effect of zardaverine on signaling through the GR. The second attributed zardaverine toxicity in HeLa cells to promotion of the interaction of phosphodiesterase 3A and the growth regulatory protein Schlafen 12. We speculate that this work may provide a possible mechanism for zardaverine action in CS242 ERMS, although we have not yet tested this hypothesis. In conclusion, we have identified zardaverine as a potent cytotoxic agent in a CS-derived ERMS cell line and in HeLa. Although we have ruled out some possibilities, the mechanism of action of zardaverine in CS242 ERMS remains to be determined.

Costello syndrome (CS) arises from a typically paternally derived germline mutation in the proto-oncogene HRAS, and is considered a rasopathy. CS results in failure-to-thrive, intellectual disabilities, short stature, coarse facial features, skeletal abnormalities, congenital heart disease, and a predisposition for cancer, most commonly embryonal rhabdomyosarcoma (ERMS). The goal of this study was to characterize CS ERMS at the molecular level and to determine how divergent it is from sporadic ERMS. We characterized eleven ERMS tumors from eight unrelated CS patients, carrying paternally derived HRAS c.34G>A (p.Gly12Ser; 6) or c.35G>C (p.Gly12Ala; 2) mutations. Loss of heterozygosity (LOH) was evaluated in all CS ERMS by microarray and/or short tandem repeat (STR) markers spanning the entire chromosome 11. Eight CS ERMS tumors displayed complete paternal uniparental disomy of chromosome 11 (pUPD11), whereas two displayed UPD only at 11p and a second primary ERMS tumor showed UPD limited to 11p15.5, the classical hallmark for ERMS. Three sporadic ERMS cell lines (RD, Rh36, Rh18) and eight formalin fixed paraffin embedded (FFPE) ERMS tumors were also analyzed for RAS mutations and LOH status. We found a higher than anticipated frequency of RAS mutations (HRAS or NRAS; 50%) in sporadic ERMS cell lines/tumors. Unexpectedly, complete uniparental disomy (UPD11) was observed in five specimens, while the other six showed LOH extending across the p and q arms of chromosome 11. In this study, we are able to clearly demonstrate complete UPD11 in both syndromic and sporadic ERMS. © 2016 Wiley Periodicals, Inc., (© 2016 Wiley Periodicals, Inc.)

Heterozygous germline mutations in the proto-oncogene HRAS cause Costello syndrome (CS), an intellectual disability condition with severe failure to thrive, cardiac abnormalities, predisposition to tumors, and neurologic abnormalities. More than 80% of patients share the HRAS mutation c.34G>A (p.Gly12Ser) associated with the typical, relatively homogeneous phenotype. Rarer mutations occurred in individuals with an attenuated phenotype and less characteristic facial features. Most pathogenic HRAS alterations affect hydrolytic HRAS activity resulting in constitutive activation. "Gain-of-function" and "hyperactivation" concerning downstream pathways are widely used to explain the molecular basis and dysregulation of the RAS-MAPK pathway is the biologic mechanism shared amongst rasopathies. Panel testing for rasopathies identified a novel HRAS mutation (c.179G>A; p.Gly60Asp) in three individuals with attenuated features of Costello syndrome. De novo paternal origin occurred in two, transmission from a heterozygous mother in the third. Individuals showed subtle facial features; curly hair and relative macrocephaly were seen in three; atrial tachycardia and learning difficulties in two, and pulmonic valve dysplasia and mildly thickened left ventricle in one. None had severe failure to thrive, intellectual disability or cancer, underscoring the need to consider HRAS mutations in individuals with an unspecific rasopathy phenotype. Functional studies revealed strongly increased HRAS(Gly60Asp) binding to RAF1, but not to other signaling effectors. Hyperactivation of the MAPK downstream signaling pathways was absent. Our results indicate that an increase in the proportion of activated RAS downstream signaling components does not entirely explain the molecular basis of CS. We conclude that the phenotypic variability in CS recapitulates variable qualities of molecular dysfunction., (© 2015 Wiley Periodicals, Inc.)

Proximal spinal muscular atrophy (SMA) is an early-onset motor neuron disease characterized by loss of α-motor neurons and associated muscle atrophy. SMA is caused by deletion or other disabling mutation of survival motor neuron 1 (SMN1). In the human genome, a large duplication of the SMN-containing region gives rise to a second copy of this gene (SMN2) that is distinguishable by a single nucleotide change in exon 7. Within the SMA population, there is substantial variation in SMN2 copy number; in general, those individuals with SMA who have a high SMN2 copy number have a milder disease. Because SMN2 functions as a disease modifier, its accurate copy number determination may have clinical relevance. In this study, we describe the development of an assay to assess SMN1 and SMN2 copy numbers in DNA samples using an array-based digital PCR (dPCR) system. This dPCR assay can accurately and reliably measure the number of SMN1 and SMN2 copies in DNA samples. In a cohort of SMA patient-derived cell lines, the assay confirmed a strong inverse correlation between SMN2 copy number and disease severity. Array dPCR is a practical technique to determine, accurately and reliably, SMN1 and SMN2 copy numbers from SMA samples.

Next-generation sequencing (NGS) technologies provide the potential for developing high-throughput and low-cost platforms for clinical diagnostics. A limiting factor to clinical applications of genomic NGS is downstream bioinformatics analysis for data interpretation. We have developed an integrated approach for end-to-end clinical NGS data analysis from variant detection to functional profiling. Robust bioinformatics pipelines were implemented for genome alignment, single nucleotide polymorphism (SNP), small insertion/deletion (InDel), and copy number variation (CNV) detection of whole exome sequencing (WES) data from the Illumina platform. Quality-control metrics were analyzed at each step of the pipeline by use of a validated training dataset to ensure data integrity for clinical applications. We annotate the variants with data regarding the disease population and variant impact. Custom algorithms were developed to filter variants based on criteria, such as quality of variant, inheritance pattern, and impact of variant on protein function. The developed clinical variant pipeline links the identified rare variants to Integrated Genome Viewer for visualization in a genomic context and to the Protein Information Resource's iProXpress for rich protein and disease information. With the application of our system of annotations, prioritizations, inheritance filters, and functional profiling and analysis, we have created a unique methodology for downstream variant filtering that empowers clinicians and researchers to interpret more effectively the relevance of genomic alterations within a rare genetic disease.

Lateral meningocele syndrome (LMS, OMIM%130720), also known as Lehman syndrome, is a very rare skeletal disorder with facial anomalies, hypotonia and meningocele-related neurologic dysfunction. The characteristic lateral meningoceles represent the severe end of the dural ectasia spectrum and are typically most severe in the lower spine. Facial features of LMS include hypertelorism and telecanthus, high arched eyebrows, ptosis, midfacial hypoplasia, micrognathia, high and narrow palate, low-set ears and a hypotonic appearance. Hyperextensibility, hernias and scoliosis reflect a connective tissue abnormality, and aortic dilation, a high-pitched nasal voice, wormian bones and osteolysis may be present. Lateral meningocele syndrome has phenotypic overlap with Hajdu-Cheney syndrome. We performed exome resequencing in five unrelated individuals with LMS and identified heterozygous truncating NOTCH3 mutations. In an additional unrelated individual Sanger sequencing revealed a deleterious variant in the same exon 33. In total, five novel de novo NOTCH3 mutations were identified in six unrelated patients. One had a 26 bp deletion (c.6461_6486del, p.G2154fsTer78), two carried the same single base pair insertion (c.6692_93insC, p.P2231fsTer11), and three individuals had a nonsense point mutation at c.6247A > T (pK2083*), c.6663C > G (p.Y2221*) or c.6732C > A, (p.Y2244*). All mutations cluster into the last coding exon, resulting in premature termination of the protein and truncation of the negative regulatory proline-glutamate-serine-threonine rich PEST domain. Our results suggest that mutant mRNA products escape nonsense mediated decay. The truncated NOTCH3 may cause gain-of-function through decreased clearance of the active intracellular product, resembling NOTCH2 mutations in the clinically related Hajdu-Cheney syndrome and contrasting the NOTCH3 missense mutations causing CADASIL., (© 2014 Wiley Periodicals, Inc.)

Patients with physical findings suggestive of Treacher Collins syndrome (TCS) or mandibulofacial dysostosis (MFD) and macrocytic anemia diagnostic of Diamond-Blackfan anemia (DBA) have been reported. Disease-causing genes have been identified for TCS and other MFDs. Mutations in several ribosomal protein genes and the transcription factor GATA1 result in DBA. However, no disease-causing mutation had been identified in the reported patients with the combination of TCS/MFD and DBA phenotype, and we hypothesized that pathogenic mutations in a single gene could be identified using whole exome analysis. We studied probands from six unrelated families. Combining exome analysis and Sanger sequencing, we identified likely pathogenic mutations in 5/6 families. Two mutations in unrelated families were seen in RPS26, the known DBA10 gene. One variant was predicted to affect mRNA splicing, and the other to lead to protein truncation. In another family a likely pathogenic X-linked mutation affecting a highly conserved residue was found in TSR2, which encodes a direct binding partner of RPS26. De novo mutations affecting the RPS28 start codon were found in two unrelated probands, identifying RPS28 as a novel disease gene. We conclude that the phenotype combining features of TCS with DBA is genetically heterogeneous. Each of the pathogenic variants identified is predicted to impede ribosome biogenesis, which in turn could result in altered cell growth and proliferation, causing abnormal embryologic development, defective erythropoiesis and reduced growth. The phenotype combining TCS/MFD and DBA is highly variable, overlaps with DBA and lies within the phenotypic spectrum of ribosomopathies. © 2014 Wiley Periodicals, Inc., (© 2014 Wiley Periodicals, Inc.)

Noonan syndrome is a heterogenous rasopathy typically presenting with short stature, characteristic facial features, cardiac abnormalities including pulmonic valve stenosis, ASD and hypertrophic cardiomyopathy (HCM), cryptorchidism, ectodermal abnormalities, and learning differences. The phenotype is variable, and limited genotype phenotype correlation exists with SOS1 mutations often associated with normal cognition and stature, RAF1 mutations entailing a high HCM risk, and certain PTPN11 mutations predisposing to juvenile myelomonocytic leukemia. The recently identified SHOC2 mutation (p.Ser2Gly) causes Noonan syndrome with loose anagen hair. We report five patients with this mutation. All had skin hyperpigmentation, sparse light colored hair, increased fine wrinkles, ligamentous laxity, developmental delay, and 4/4 had a structural cardiac anomaly. Hypotonia and macrocephaly occurred in 4/5 (80%); 3/5 (60%) had polyhydramnios, increased birth weight or required use of a feeding tube. Distinctive brain abnormalities included relative megalencephaly and enlarged subarachnoid spaces suggestive of benign external hydrocephalus, and a relatively small posterior fossa as indicated by a vertical tentorium. The combination of a large brain with a small posterior fossa likely resulted in the high rate of cerebellar tonsillar ectopia (3/4; 75%). Periventricular nodular heterotopia was seen in one patient with a thick and dysplastic corpus callosum. We report on the first hematologic neoplasm, myelofibrosis, in a 2-year-old patient with SHOC2 mutation. Myelofibrosis is exceedingly rare in children and young adults. The absence of a somatic JAK2 mutation, seen in the majority of patients with myelofibrosis, is noteworthy as it suggests that germline or somatic SHOC2 mutations are causally involved in myelofibrosis., (Copyright © 2013 Wiley Periodicals, Inc.)

Costello syndrome (CS) is a rare genetic disorder caused by germline mutations in the HRAS proto-oncogene which belongs to the family of syndromes called rasopathies. HRAS plays a key role in synaptic long-term potentiation (LTP) and memory formation. Prior research has found impaired recall memory in CS despite enhancement in LTP that would predict memory preservation. Based on findings in other rasopathies, we hypothesized that the memory deficit in CS would be specific to recall, and that recognition memory would show relative preservation. Memory was tested using word-list learning and story memory tasks with both recall and recognition trials, a design that allowed us to examine these processes separately. Participants were 11 adolescents and young adults with molecularly confirmed CS, all of whom fell in the mild to moderate range of intellectual disability. Results indicated a clear dissociation between verbal recall, which was impaired (M = 69 ± 14), and recognition memory, which was relatively intact (M = 86 ± 14). Story recognition was highly correlated with listening comprehension (r = 0.986), which also fell in the low-average range (M = 80 ± 12.9). Performance on other measures of linguistic ability and academic skills was impaired. The findings suggest relatively preserved recognition memory that also provides some support for verbal comprehension. This is the first report of relatively normal performance in a cognitive domain in CS. Further research is needed to better understand the mechanisms by which altered RAS-MAPK signaling affects neuronal plasticity and memory processes in the brain., (Copyright © 2013 Wiley Periodicals, Inc.)

Plasma membrane Ca(2+)-ATPase isoform 4 (PMCA4) is the primary Ca(2+) efflux pump in murine sperm, where it regulates motility. In Pmca4 null sperm, motility loss results in infertility. We have shown that murine sperm PMCA4b interacts with Ca(2+)/CaM-dependent serine kinase (CASK) in regulating Ca(2+) homeostasis and motility. However, recent work indicated that the bovine PMCA4a splice variant (missing in testis) is epididymally expressed, along with 4b, and may be transferred to sperm. Here we show, via conventional and in situ RT-PCR, that both the splice variants of Pmca4 mRNA are expressed in murine testis and throughout the epididymis. Immunofluorescence localized PMCA4a to the apical membrane of the epididymal epithelium, and Western analysis not only confirmed its presence but showed for the first time that PMCA4a and PMCA4b are secreted in the epididymal luminal fluid (ELF), from which epididymosomes containing PMCA4a were isolated. Flow cytometry indicated the presence of PMCA4a on mature caudal sperm where it was increased ~5-fold compared to caput sperm (detected by Western blotting) and ~2-fold after incubation in ELF, revealing in vitro uptake and implicating PMCA4a in epididymal sperm maturation. Coimmunoprecipitation using pan-PMCA4 antibodies, revealed that both variants associate with CASK, suggesting their presence in a complex. Because they have different kinetic properties for Ca(2+) transport and different abilities to bind to CASK, our study suggests a mechanism for combining the functional attributes of both PMCA4 variants, leading to heightened efficiency of the pump in the maintenance of Ca(2+) homeostasis, which is crucial for normal motility and male fertility.

Purpose: Costello syndrome, a rare genetic disorder with multisystemic involvement, is caused by germline HRAS mutations. Because several different missense mutations have been reported, a severity scoring system was developed to assess a possible genotype-phenotype correlation., Methods: Records of 78 individuals with Costello syndrome were scored in early childhood, childhood, and young adulthood by a reviewer blinded to the individuals' specific mutations. These scores were based on certain medically relevant feeding, neurologic, orthopedic, endocrine, cardiac, malignancy, and mortality manifestations. Individuals' severity scores were then grouped by the particular HRAS mutation. The mixed-model approach for repeated-measures analysis of variance with unstructured within-subject correlation, pairwise comparisons, and contrast were used to determine whether the severity scores differed by mutation., Results: Although the sample size was small, individuals with the p.G12A or p.G12C HRAS change were more severely affected than those with other HRAS mutations. Regardless of the mutation, severity did not increase significantly over time., Conclusion: Despite its limitations, including the small number of individuals with rare mutations and possibly incomplete medical records, this work providing the first quantitative assessment of phenotypic severity in a Costello syndrome cohort supports a medically relevant genotype-phenotype correlation.

Costello syndrome is a rare condition due to heterozygous germline mutations in the proto-oncogene HRAS. It affects multiple organ systems and includes severe failure-to-thrive, short stature, and macrocephaly. The goal of this study was to develop Costello syndrome-specific growth curves. We collected height, weight, and head circumference (OFC) measurements from 94 individuals (45 males and 49 females). Their HRAS mutation spectrum reflects previously published cohorts, with p.G12S in 77.7%. Participants received medical care, therefore our data does not reflect natural history per se, but rather growth with nutritional support. Due to limited cohort size, we analyzed data from males and females together. Weight-for-age data included 417 separate measurements from 80 individuals age 0-36 months, and 585 measurements from 82 individuals for age 0-10 years. Height-for-age data were derived from 391 measurements from 77 individuals age 0-36 months, and 591 measurements from 90 individuals age 0-10 years. Measurements obtained after growth hormone exposure in 15 individuals were excluded in this analysis. The OFC curve was derived from 221 measurements from 55 individuals age 0-36 months. Centiles (5th, 50th, and 95th) were estimated across the age continuum for each growth parameter, and compared to gender-specific curves for average stature individuals. The resulting curves demonstrate very slow weight gain in the first 2 years. Short stature is seen in many, but after age 4 years the 95th centile for height falls within the low normal range for average stature children. Head circumference curves largely overlap those for average stature, reflecting relative macrocephaly., (Copyright © 2012 Wiley Periodicals, Inc.)

Costello syndrome is caused by HRAS germline mutations affecting Gly(12) or Gly(13) in >90% of cases and these are associated with a relatively homogeneous phenotype. Rarer mutations in other HRAS codons were reported in patients with an attenuated or mild phenotype. Disease-associated HRAS missense mutations result in constitutive HRAS activation and increased RAF-MEK-ERK and PI3K-AKT signal flow. Here we report on a novel heterozygous HRAS germline alteration, c.266C>G (p.S89C), in a girl presenting with severe fetal hydrops and pleural effusion, followed by a more benign postnatal course. A sibling with the same mutation and fetal polyhydramnios showed a Dandy-Walker malformation; his postnatal course was complicated by severe feeding difficulties. Their apparently asymptomatic father is heterozygous for the c.266C>G change. By functional analyses we identified reduced levels of active HRAS(S89C) and diminished MEK, ERK and AKT phosphorylation in cells overexpressing HRAS(S89C) , which represent novel consequences of disease-associated HRAS mutations. Given our patients' difficult neonatal course and presence of this change in their asymptomatic father, we hypothesize that its harmful consequences may be time limited, with the late fetal stage being most sensitive. Alternatively, the phenotype may develop only in the presence of an additional as-yet-unknown genetic modifier. While the pathogenicity of the HRAS c.266C>G change remains unproven, our data may illustrate wide functional and phenotypic variability of germline HRAS mutations., (Copyright © 2012 Wiley Periodicals, Inc.)

We describe a series of seven male patients from six different families with skeletal dysplasia, characteristic facial features, and developmental delay. Skeletal findings include patellar dislocation, short tubular bones, mild metaphyseal changes, brachymetacarpalia with stub thumbs, short femoral necks, shallow acetabular roofs, and platyspondyly. Facial features include: a flattened midface with broad nasal bridge, cleft palate or bifid uvula and synophrys. All of the patients demonstrated pre-school onset of a cognitive developmental delay with a shortened attention span. Some of the cognitive delay was masked by a warm and engaging personality. We posit that these individuals have a newly recognized syndrome characterized by the described features. There is some phenotypic overlap between these patients and Desbuquois dysplasia; however molecular testing demonstrated that this is a distinct disorder. Given the family information available for each patient, we are suspicious that the constellation of findings reported herein could be an X-linked recessive syndrome., (Copyright © 2012 Wiley Periodicals, Inc.)

Costello syndrome was delineated based on its distinctive phenotype including severe failure-to-thrive with macrocephaly, characteristic facial features, hypertrophic cardiomyopathy, papillomata, malignant tumors, and cognitive impairment. Heterozygous germline mutations in the proto-oncogene HRAS cause Costello syndrome, and its inheritance pattern would thus be autosomal dominant. With exception of two instances of parental mosaicism, one presumed gonadal and the other proven somatic mosaicism for the p.G12S change, all published cases resulted from de novo mutations, typically arising in the paternal germline. More than 90% of these mutations affect the glycine residues in position 12 or 13, and result in a gain-of-function of the altered protein. A rare heterozygous HRAS alteration (c.173C > T; p.T58I) associated with an attenuated phenotype was previously reported in one patient. We identified two additional individuals with this mutation, father and son. Further studies supported origin of the alteration in the grand-paternal germline. Transmission of the mutation underscores its attenuated phenotype compatible with reproduction. We reviewed the phenotype in the newly identified individuals (Patient 1, 2) and include updated information on the first previously reported individual with HRAS p.T58I (Patient 3). Macrocephaly was present in all three. Cardiac findings included hypertrophic cardiomyopathy with double-chambered right ventricle; or mitral valve prolapse in one patient each. While subtle neurologic abnormalities or developmental delay were present in all, only one showed significant cognitive and functional impairment. None developed papillomata or a malignant tumor. Genetic counseling for Costello syndrome needs to take into consideration the particular HRAS mutation., (Copyright © 2012 Wiley Periodicals, Inc.)

Costello syndrome was first reported based on its characteristic phenotype. Its presentation affects multiple organ systems, including severe failure-to-thrive with macrocephaly, characteristic facial features, hypertrophic cardiomyopathy, papillomata, malignant tumors, and cognitive impairment. Heterozygous germline mutations in the proto-oncogene HRAS have been recognized to cause Costello syndrome, and its inheritance pattern would thus be autosomal dominant. Here, we report on the identification of an HRAS mutation c.34G>A, predicting a p.G12S amino acid substitution, in the surviving brother of a previously reported sibling pair, and documentation of the same change in autopsy material from his deceased sister. This represents, to our knowledge, the first molecularly confirmed Costello syndrome in siblings. We did not detect the mutation in a heterozygous state or mosaicism in peripheral white blood cell or cheek swab-derived DNA samples from either parent. Using single nucleotide polymorphic markers and allele-specific amplification, we clearly identified the mutation in the surviving sibling to be of maternal origin. While we cannot exclude two independently occurring de novo mutations, the complete sharing of polymorphic markers around the mutation site in both siblings supports maternal germ cell mosaicism. Recurrence risk counseling for families with apparently de novo occurring autosomal dominant conditions includes discussion of germ cell mosaicism, and this report underscores the applicability of this concern to Costello syndrome., (Copyright © 2011 Wiley-Liss, Inc.)

Costello syndrome is characterized by severe failure-to-thrive, short stature, cardiac abnormalities (heart defects, tachyarrhythmia, and hypertrophic cardiomyopathy (HCM)), distinctive facial features, a predisposition to papillomata and malignant tumors, postnatal cerebellar overgrowth resulting in Chiari 1 malformation, and cognitive disabilities. De novo germline mutations in the proto-oncogene HRAS cause Costello syndrome. Most mutations affect the glycine residues in position 12 or 13, and more than 80% of patients share p.G12S. To test the hypothesis that subtle genotype-phenotype differences exist, we report the first cohort comparison between 12 Costello syndrome individuals with p.G13C and individuals with p.G12S. The individuals with p.G13C had many typical findings including polyhydramnios, failure-to-thrive, HCM, macrocephaly with posterior fossa crowding, and developmental delay. Subjectively, their facial features were less coarse. Statistically significant differences included the absence of multifocal atrial tachycardia (P-value = 0.033), ulnar deviation of the wrist (P < 0.001) and papillomata (P = 0.003), and fewer neurosurgical procedures (P = 0.024). Fewer individuals with p.G13C had short stature (height below -2 SD) without use of growth hormone (P < 0.001). The noteworthy absence of malignant tumors did not reach statistical significance. Novel ectodermal findings were noted in individuals with p.G13C, including loose anagen hair resulting in easily pluckable hair with a matted appearance, different from the tight curls typical for most Costello syndrome individuals. Unusually long eye lashes requiring trimming are a novel finding we termed dolichocilia. These distinctive ectodermal findings suggest a cell type specific effect of this particular mutation. Additional patients are needed to validate these findings., (Copyright © 2011 Wiley-Liss, Inc.)

Cardio-facio-cutaneous (CFC) syndrome is characterized by a variable degree of cognitive impairment, and multiple congenital anomalies including characteristic facies, cardiac, and ectodermal abnormalities. CFC syndrome is caused by mutations in the genes BRAF, MEK1, or MEK2. Here we provide a follow-up report on two patients presenting distinct facial appearance and other features of the syndrome, and we present the first molecular evidence of paternal origin for a CFC-causing germline mutation. Brain imaging revealed a lipoma of the corpus callosum and periventricular leukoencephalopathy as well as a hypoplastic corpus callosum, and defects in myelinization, in each patient, respectively. A review of the literature showed that, although non-specific, ventriculomegaly, hydrocephalus, and cortical atrophy represent the most frequent imaging findings of brain anomalies in CFC syndrome. CNS abnormalities are significant diagnostic features of CFC syndrome and a brain MRI is recommended in individuals diagnosed with CFC or suspected of having CFC syndrome., (Copyright © 2011 Wiley-Liss, Inc.)

Clinical and molecular analyses of Costello syndrome are proceeding at a rapid pace, including the delineation of the adult phenotype. We designed a two-part survey in order to describe the quality of life (QoL) of older individuals with Costello syndrome. The survey consisted of the Costello syndrome quality of life (CSQoL): Caregiver Questionnaire, to obtain objective information such as skills, activities, and medical issues from caregivers; and the CSQoL:Self-Questionnaire assessing subjective information including self-esteem, life satisfaction, and interpersonal relations from affected individuals. Thirteen of 18 (72%) individuals with Costello syndrome (age 16-34 years, mean 22 years) and caregiver pairs responded. The data were analyzed to study day-to-day life, and to determine potential impediments on QoL for older individuals with Costello syndrome. The CSQoL:Caregiver total scores were significantly lower than the CSQoL:Self total scores as demonstrated by the Wilcoxon Signed Ranks Test (P < 0.008). The CSQoL:Caregiver total scores appear negatively correlated with total number of medical issues (r = -0.549; P = 0.065). No association was found between the CSQoL:Self scores and total number of medical issues (r = -0.107; P = 0.769). Four impediments to QoL for individuals with Costello syndrome were identified: relationships outside of their immediate circle of family and friends, lack of independence, male gender, and the presence of major medical issues. This information may be useful to the families and health care professionals of adults with Costello syndrome. As a measurable characteristic, QoL may have utility as a metric in future therapeutic trials.

Costello syndrome is a rare rasopathy caused by germline mutations in the oncogene HRAS resulting in increased signal transduction through the Ras/mitogen-activated protein kinase pathway. In contrast to the more common rasopathies, such as neurofibromatosis type 1 and Noonan syndrome, limited information is available on standardized cognitive testing in this cohort. Past research indicated a mean average IQ in the mild mental retardation range, with strengths in fluid reasoning (FR) and weakness in expressive language, as well as static skills over time. Here we report on standardized IQ and adaptive functioning in 18 individuals with Costello syndrome, nine males and nine females, and longitudinal development for 11 who had previous testing. The overall IQ, ranging from severe mental retardation to the average range, with a mean in the mildly mentally retarded range, was again found to be stable, but an interesting pattern in the development of nonverbal FR was identified. Participants showed an improvement in nonverbal FR, followed by stable skills thereafter, suggesting a "late bloomer" effect in late childhood/early adolescence. Overall adaptive functioning fell into the range of Intellectual Disability for 70% of subjects, with Socialization as a relative strength and Daily Living Skills an area of relative difficulty. Interestingly, females were found to be higher functioning than males in all domains, including Communication, Daily Living Skills and Socialization. Caregivers reported significantly more behavioral concerns in males, including internalizing, externalizing, and other maladaptive behaviors. In contrast, no gender differences were found in cognitive or visuomotor functioning.

Costello syndrome is a rare congenital anomaly syndrome associated with mental retardation and predisposition to benign and malignant tumors, caused by heterozygous missense mutations in the HRAS oncogene. Previously, all molecularly analyzed mutations appeared de novo, and most arose in the paternal germline. A single patient with somatic mosaicism for a Costello syndrome causing HRAS mutation has been reported. Here we describe the first documented transmission of an HRAS mutation from a parent with somatic mosaicism to a child with typical Costello syndrome. Prior to the identification of the underlying gene mutation in Costello syndrome, this family had been identified clinically. The proband was subsequently found to carry a G12S HRAS germline mutation. Testing of the parents for parental origin identified his father as mosaic for the same HRAS mutation. The mother was found not to carry an HRAS mutation. The causative familial mutation is identified as a c.34G > A, which is the most common mutation in the HRAS gene in patients with Costello syndrome. The father carries the mutation in 7-8% of his alleles. This is the second case of mosaicism observed in Costello syndrome and the first direct molecular evidence of father-to-son transmission of the disease-causing mutation. Our observation underlines the importance of parental evaluation, and may have implications for genetic counseling and clinical practice., (2009 Wiley-Liss, Inc.)

Costello syndrome is a rare congenital disorder typically characterized by severe failure-to-thrive, cardiac abnormalities including tachyarrhythmia and hypertrophic cardiomyopathy, distinctive facial features, a predisposition to papillomata and malignant tumors, neurologic abnormalities, developmental delay, and mental retardation. Its underlying cause is de novo germline mutations in the oncogene HRAS. Almost all Costello syndrome mutations affect one of the glycine residues in position 12 or 13 of the protein product. More than 80% of patients with Costello syndrome share the same underlying mutation, resulting in a G12S amino acid change. We report on two patients with novel HRAS mutations affecting amino acids 58 (T58I) and 146 (A146V), respectively. Despite facial features that appear less coarse than those typically seen in Costello patients, both patients show many of the physical and developmental problems characteristic for Costello syndrome. These novel HRAS mutations may be less common than the frequently reported G12S change, or patients with these changes may be undiagnosed due to their less coarse facial features. In addition to the findings previously known to occur in Costello syndrome, one of our patients had hypertrophic pyloric stenosis. This led us to review the medical histories on a cohort of proven HRAS mutation positive Costello syndrome patients, and we found a statistically significantly (P < 0.001) increased frequency of pyloric stenosis in Costello syndrome (5/58) compared to the general population frequency of 2-3/1,000. Thus we add hypertrophic pyloric stenosis to the abnormalities seen with increased frequency in Costello syndrome., ((c) 2008 Wiley-Liss, Inc.)

Costello syndrome encompasses pre- and postnatal medical problems including polyhydramnios, failure to thrive, cardiac complications, and an increased risk for solid tumors. Hypotonia and developmental delay are typical in infancy, and mental retardation can be diagnosed in older patients. Previous studies on the cognitive development in Costello syndrome relied on clinically diagnosed cases. The recent discovery of heterozygous HRAS mutations allows for molecular confirmation of the clinical diagnoses. We report here on cognitive abilities and adaptive behavior in the first cohort of patients with molecularly confirmed diagnoses. Further, this is the first longitudinal assessment of cognitive function in this patient population. Sixteen patients with identified HRAS mutations were tested, and 14 completed the Leiter International Performance Scale-Revised. The mean Full-Scale IQ score of 57 (range 30-87) was within the range of mild Mental Retardation. Analysis of test component subsets showed a relative strength in Fluid Reasoning with a mean score of 69 (range 48-98), in the mild range of Mental Retardation. Longitudinal analysis was performed for 12 patients by comparison of data obtained at the first evaluation (T1) to results obtained 2 years later (T2). In these patients intellectual and language abilities remained stable, and no deterioration was seen. We have thus shown that Costello syndrome is a static condition regarding intellectual and language abilities. The Leiter-R Memory Screen indicated functioning in the mildly delayed range for the majority of patients. Adaptive behavior was evaluated using the Vineland tool, and longitudinal data comparison for adaptive behavior showed improvements in Daily Living Skills, Communication, and the Adaptive Behavior Composite. However, these results must be interpreted cautiously as the measuring tool was updated from T1 to T2. Receptive language skills were measured with the Peabody Picture Vocabulary Test-III, showing a mean receptive vocabulary standard score of 65 (SD 15) in the Extremely Low range. Expressive language skills, as measured by the Expressive Vocabulary Test (EVT), scored a mean of 51 (SD 14), in the Extremely Low range. However, half of the subjects obtained the lowest possible score on the EVT, demonstrating that this is not the ideal tool for use in this patient population., ((c) 2007 Wiley-Liss, Inc.)

Because Cardio-facio-cutaneous (CFC) syndrome has significant phenotypic overlap with Costello syndrome, it may be difficult to establish the diagnosis on a clinical basis. The recent discoveries of germline HRAS mutations in patients with Costello syndrome and mutations in BRAF, MEK1, and MEK2 in CFC syndrome uncovered the biologic mechanism for the shared phenotypic findings based on the close interaction of the affected gene products within the MAP kinase pathway. We evaluated a series of patients who were either clinically diagnosed with Costello syndrome, or in whom the diagnoses of both Costello and CFC syndromes were considered. After excluding mutations in HRAS, we identified eight changes in BRAF and five in MEK1. Five mutations are novel, and all changes occurred de novo among those triads tested. A review of the clinical abnormalities showed important differences between patients with either a BRAF or MEK1 mutation, and those previously reported with an HRAS mutation. Statistical significance was achieved, despite the relatively small number of patients with BRAF and MEK1 mutations reported here, for polyhydramnios, growth hormone deficiency and the presence of more than one papilloma, which were less common in CFC compared to HRAS mutation positive patients. Although both CFC and Costello syndrome are characterized by cardiac abnormalities in about three-fourths of patients, the pattern of congenital heart defects (CHD), hypertrophic cardiomyopathy (HCM), and tachycardia differs somewhat. CHD, especially pulmonic stenosis associated with a secundum-type atrial septal defect, are more common in CFC than Costello syndrome (P = 0.02). Atrial tachycardia is less frequent in CFC patients with BRAF or MEK1 mutations, compared to Costello syndrome patients with HRAS mutation (P = 0.04). Chaotic atrial rhythm or multifocal atrial tachycardia was observed only in Costello syndrome. Malignant tumors have been viewed as characteristic for Costello syndrome due to HRAS mutations, however, we report here on a MEK1 mutation in a patient with a malignant tumor, a hepatoblastoma. Although this indicates that the presence of a tumor is not specific for Costello syndrome with HRAS mutation, it is noteworthy that the tumor histology differs from those commonly seen in Costello syndrome. Based on these clinical differences we suggest that patients with BRAF and MEK mutations should be diagnosed with CFC syndrome, and the diagnosis of Costello syndrome be reserved for patients with HRAS mutations., ((c) 2007 Wiley-Liss, Inc.)

Cardio-facio-cutaneous syndrome (CFC) and Costello syndrome (CS) are disorders with an overlapping spectrum of congenital anomalies. Mutations in the RAS-MAPK pathway have recently been reported in both of these syndromes, with HRAS mutations characteristic for CS and BRAF and MEK1/2 mutations for CFC. We report on a 3-year-old boy who underwent a cardiac transplant at age 8 months for hypertrophic cardiomyopathy; he was subsequently suspected to have CS. At age 35 months he presented with an intra-cardiac mass that was diagnosed as metastatic hepatoblastoma. Although hepatoblastoma is not known to have an increased frequency in immunocompromised patients, questions were raised as whether the post-transplant immuno-suppressive therapy played a role in tumor development. The patient died shortly thereafter and his post-mortem DNA analysis revealed a MEK1 mutation (Y130C) previously reported in CFC. While CS is associated with increased cancer risk, only a single case of leukemia has been reported in a patient with CFC, making this the first case of a solid tumor reported in a patient with CFC., ((c) 2007 Wiley-Liss, Inc.)

De novo heterozygous HRAS point mutations have been reported in more than 81 patients with Costello syndrome (CS), but genotype/phenotype correlation remains incomplete because the majority of patients share a common mutation, G12S, seen in 65/81 (80%). Somatic HRAS mutations have previously been identified in solid tumors, and mutation hot spots related to a gain-of-function effect of the gene product are known. The germline mutations causing CS occur at these hot spots and convey a gain-of-function effect, thus accounting for the greatly increased cancer risk. Diagnostic testing for HRAS mutations is now available and the identification of a mutation in a patient with consistent clinical findings confirms a diagnosis of CS. It is not clear yet if the absence of an HRAS mutation precludes a diagnosis of CS. Because there is a significant overlap in the clinical findings of Costello, cardio-facio-cutaneous, and Noonan syndromes, diagnostic uncertainty remains in patients lacking an HRAS mutation. We report here on a female with findings suggestive of CS in whom mutation analysis performed with standard techniques on white blood cell derived DNA did not show an HRAS mutation. However, analysis of DNA derived from three independently collected buccal swabs showed a sequence change qualitatively consistent with the G12S mutation. Allelic quantitation showed the presence of the mutation in approximately 25%-30% of the sampled buccal cells. In this patient, standard technology failed to identify the disease causing mutation on DNA derived from a blood sample, highlighting the potential pitfalls in the interpretation of negative mutation studies. This is the first reported CS patient mosaic for the common HRAS mutation, likely due to a somatic mutation occurring very early in fetal development., ((c) 2006 Wiley-Liss, Inc.)

Costello syndrome (CS) is a rare congenital condition caused by heterozygous de novo missense mutations affecting the codon for glycine 12 or 13 of the HRAS gene. We have identified 39 CS patients harboring the p.Gly12Ser mutation (NM&#95;005343.2:c.34 G > A), two patients with c.35G > C mutations resulting in p.Gly12Ala substitutions, and one patient carrying the p.Gly13Cys substitution (c.37G > A). We analyzed the region flanking the mutated sites in 42 probands and 59 parents, and used four polymorphic markers to trace the parental origin of the germline mutations: one highly polymorphic hexanucleotide (GGGCCT) repeat region, defining three alleles with different numbers of repeat units (two, three, or four), and three SNPs. One of the SNPs, rs12628 (c.81T > C), was found in strong linkage disequilibrium with the hexanucleotide repeat region. Out of a total of 24 probands with polymorphic markers, 16 informative families were tested and the paternal origin of the germline mutation was found in 14 CS probands; a distribution that is neither consistent with an equal likelihood of mutations arising in either parent (P = 0.0018), nor with exclusive paternal origin.

Sperm adhesion molecule1 (SPAM1), the best characterized hyaluronidase gene, is abundantly expressed in the testis. We attempted to overexpress mouse Spam1 via transgenesis using either the endogenous promoter in a BAC or a heterologous Protamine1 promoter for a Spam1 cDNA transgene. Although transgene-copy numbers ranged from 2 to 15 and transgenic transcripts were expressed, there was a general failure of overexpression of the RNA and protein in the testis of all seven founders. Also, three transgenic lines showed a modest downregulation or co-suppression of the RNA for Spam1 and Hyal5, present on the BAC. We provide evidence for the potential involvement of two co-ordinating post-transcriptional regulatory processes in the failure of overexpression: abundant endogenous antisense RNA and adenosine-uridine (AU)-rich element-mediated regulation of RNA turnover. We demonstrate that AU-rich elements (AREs) in the 3'UTR of mRNAs, well-known to interact with trans-acting proteins to target the RNA for (in)stability, are present in Spam1 RNA and specifically bind to six testicular cytoplasmic proteins. These AU-binding proteins (AUBPs) were virtually absent from the kidney where transcripts are rare, and were shown to interact with the cytoskeleton, which modulates mRNA turnover. In addition to a role in the RNAi pathway, antisense RNA can also modulate ARE-mediated regulation of mRNA by hybridizing to the AREs and specifically silencing their function. This potentially links the two processes in the regulation of Spam1 expression. We hypothesize that testicular Spam1 RNA is regulated post-transcriptionally by cis-acting ARE(s) in the 3'UTR which recognize AUBPs and which are modulated by antisense transcripts., ((c) 2005 Wiley-Liss, Inc.)

Costello syndrome is a rare condition comprising mental retardation, distinctive facial appearance, cardiovascular abnormalities (typically pulmonic stenosis, hypertrophic cardiomyopathy, and/or atrial tachycardia), tumor predisposition, and skin and musculoskeletal abnormalities. Recently mutations in HRAS were identified in 12 Japanese and Italian patients with clinical information available on 7 of the Japanese patients. To expand the molecular delineation of Costello syndrome, we performed mutation analysis in 34 North American and 6 European (total 40) patients with Costello syndrome, and detected missense mutations in HRAS in 33 (82.5%) patients. All mutations affected either codon 12 or 13 of the protein product, with G12S occurring in 30 (90.9%) patients of the mutation-positive cases. In two patients, we found a mutation resulting in an alanine substitution in position 12 (G12A), and in one patient, we detected a novel mutation (G13C). Five different HRAS mutations have now been reported in Costello syndrome, however genotype-phenotype correlation remains incomplete., ((c) 2005 Wiley-Liss, Inc.)

Osteoporosis is a common condition characterized by reduced skeletal strength and increased susceptibility to fracture. The single major risk factor for osteoporosis is low bone mineral density (BMD) and strong evidence exists that genetic factors are in part responsible for an individual's BMD. A cohort of 40 multiplex Caucasian families selected through a proband with osteoporosis was genotyped for microsatellite markers spaced at an average of 10 cM, and linkage to femoral neck (FN), lumbar spine (LS) and trochanter (TR) BMD was analyzed using univariate and bivariate variance component linkage analysis. Maximum univariate multipoint lod-scores were 2.87 on chromosome 1p36 for FN BMD, 1.89 on 6q27 for TR BMD, and 2.15 on 7p15 for LS BMD. Results of bivariate linkage analysis were highly correlated with those of the univariate analysis, although generally less significant, suggesting the possibility that some of these susceptibility loci may exert pleiotropic effects on multiple skeletal sites.

We report that a deletion of 19 base pairs (bp) in intron 3 of the proteolipid protein (PLP/DM20) gene causes a neurological disease characterized by mild developmental delay, followed by progressive decline of acquired motor and cognitive milestones. The clinical features are associated with mild delay in myelination demonstrated by magnetic resonance imaging studies and with ongoing demyelination and axonal loss demonstrated by magnetic resonance spectroscopy. We demonstrate that the purine-rich 19bp element regulates PLP-specific splice site selection in transient transfections of chimeric constructs into cultured oligodendrocytes. Runs of 4 and 5 Gs centered in the 19bp element are critical for efficient PLP-specific splicing. The intronic element is sequence specific in oligodendrocytes and is not a repressor of PLP-specific splicing in nonglial cells. These data support the conclusion that deletion of the 19bp purine-rich region in PLP intron 3 causes a reduction in PLP message and protein, which affects myelin stability and axonal integrity.

The placenta is a critical organ in mammals required for the transport of nutrients from the mother to the fetus during gestation. Other critical functions of the placenta include hormone regulation and immune regulation. The origin of the mammals and early placenta is relatively recent in evolutionary terms, and consequently there are few placenta-specific genes. In two separate branches of mammalian evolution, gene duplications have given rise to two large families of protease genes that are expressed only by placental tissues. A family of aspartic protease genes is expressed only in artiodactyls, and a family of cysteine protease genes is expressed only in rodents. These genes have probably evolved to perform specific functions in the placenta that are carried out by broader specificity proteases in mammalian species that do not express these proteases.

Species and strain variants of a family of placentally expressed cathepsins (PECs) were cloned and sequenced in order to identify evolutionary conserved structural characteristics of this large family of cysteine proteases. Cathepsins M, P, Q, and R, are conserved in mice and rats but homologs of these genes are not found in human or rabbit placenta, showing that this family of proteases are probably restricted to rodents. Species-specific gene duplications have given rise to variants of cathepsin M in mice, and cathepsin Q in rats. Although the PECs have diverged at a greater rate than the other lysosomal cathepsins, residues around the specificity sub-sites of the individual enzymes are conserved. Strain-specific polymorphisms show that the evolutionary rate of divergence of cathepsins M and 3, the most recently duplicated pair of mouse genes, is even higher than the other PECs. In human placenta, critical functions of the PECs are probably performed by broader specificity proteases such as cathepsins B and L.

We used an RT-PCR based strategy to amplify, clone and sequence MHC class I genes transcribed in the blastocyst and placenta of BALB/c mice. The PCR primers used were capable of amplifying many novel class I sequences from genomic DNA. By comparing the resulting sequence data with known class I sequences, we identified a number of different class I genes transcribed in these tissues. These include H2-K, -D, -L and a novel sequence in blastocysts, and H2-K, -D, -L, -D2, -T9, -T13, -T17, -T18, -M2 and three additional novel sequences in placenta. We postulate that some members of this spectrum of blastocyst and placentally-expressed MHC class Ib genes may act together at the maternal-fetal interface in ways that are important for a successful pregnancy.

Because of the role major histocompatibility complex (MHC) class I b molecules may play during mouse embryonic development, we thought it would be interesting to search for additional MHC class I b molecules that might be expressed in preimplantation embryos, and in particular in the trophoblastic lineage. We therefore screened a mouse preimplantation blastocyst cDNA library for MHC class I sequences. This search led to the identification and characterization of a new MHC class I b gene, blastocyst MHC. Sequences identical to the exons and 3' untranslated region of this gene have been found in many laboratory mouse strains, as well as in the related mouse species Mus spreciligus. The presence of this gene in mouse strains of different MHC class I haplotypes argues that blastocyst MHC is a unique, newly-described gene rather than a new allele of a previously described mouse MHC class I gene. Blastocyst MHC has the structure of an MHC class I b gene, with the six exons characteristic of T-region genes. It is linked to H2-D. The amino acid sequence encoded by this gene maintains all the features of a functional antigen-presentation domain. The blastocyst MHC gene, like the human class I b gene HLA-G, is expressed at the blastocyst stage and in the placenta, and may be the mouse analog for HLA-G.