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Purpose: Pseudoachondroplasia is a rare skeletal dysplasia caused by a mutation in the COMP gene. Infants with pseudoachondroplasia present with rhizomelic dwarfism. Pseudoachondroplasia can resemble achondroplasia, which also presents with a phenotype of rhizomelic dwarfism. The differentiation between these two conditions is important because while both can present with cervicomedullary compromise, the underlying pathophysiology and its management is entirely different. Results: We present a case of a 13-year-old female patient with pseudoachondroplasia who presented with cervical myelopathy and imaging evidence of atlantoaxial instability with an os odontoideum and a retro-odontoid cystic soft tissue mass, causing C1-2 canal stenosis and cervical cord compression. She underwent C1 decompression and C1-2 posterior cervical fixation. Post-operative imaging demonstrated improved alignment of the os odontoideum, and complete resolution of the retro-odontoid soft tissue mass. We contend that retro-odontoid masses are a marker of local C1-2 joint instability and restoration of atlanto-axial alignment with posterior fixation and fusion alone is likely to be sufficient for regression of the mass and associated compression. Conclusion: Pseudoachondroplasia can present with atlantoaxial instability and cervicomedullary compromise and with retro-odontoid masses. The differentiation from achondroplasia is crucially important for surgical decision-making and management should include surgical decompression and fixation. [ABSTRACT FROM AUTHOR]

Pseudoachondroplasia (PSACH) is a rare, dominant genetic disorder affecting bone and cartilage development, characterized by short-limb short stature, brachydactyly, loose joints, joint stiffness, and pain. The disorder is caused by mutations in the COMP gene, which encodes a protein that plays a role in the formation of collagen fibers. In this study, we present the clinical and genetic characteristics of PSACH in two Chinese families. Whole-exome sequencing (WES) analysis revealed two novel missense variants in the COMP gene: NM_000095.3: c.1319G>T (p.G440V, maternal) and NM_000095.3: c.1304A>T (p.D435V, paternal-mosaic). Strikingly, both the G440V and D435V mutations were located in the same T3 repeat motif and exhibited the potential to form hydrogen bonds with each other. Upon further analysis using Missense3D and PyMOL, we ascertained that thesemutations showed the propensity to disrupt the protein structure of COMP, thus hampering its functioning. Our findings expand the existing knowledge of the genetic etiology underlying PSACH. The identification of new variants in theCOMP gene can broaden the range of mutations linked with the condition. This information can contribute to the diagnosis and genetic counseling of patients with PSACH. [ABSTRACT FROM AUTHOR]

Abstract Background Neurofibromatosis type 1 and pseudoachondroplasia are both rare autosomal dominant disorders, caused by pathogenic mutations in NF1 and COMP genes, respectively. Both neurofibromin 1 and cartilage oligomeric matrix protein (COMP) play a role in the development of the skeleton. Carrying both germline mutations has not been previously reported; however, it can affect the developing phenotype. Case presentation The index patient, an 8-year-old female presented with several skeletal and dermatologic anomalies resembling the coexistence of multiple syndromes. Her mother had dermatologic symptoms characteristic for neurofibromatosis type 1, and her father presented with distinct skeletal anomalies. NGS-based analysis revealed a heterozygous pathogenic mutation in genes NF1 and COMP in the index patient. A previously unreported heterozygous variant was detected for the NF1 gene. The sequencing of the COMP gene revealed a previously reported, pathogenic heterozygous variant that is responsible for the development of the pseudoachondroplasia phenotype. Conclusions Here, we present the case of a young female carrying pathogenic NF1 and COMP mutations, diagnosed with two distinct heritable disorders, neurofibromatosis type 1 and pseudoachondroplasia. The coincidence of two monogenic autosomal dominant disorders is rare and can pose a differential diagnostic challenge. To the best of our knowledge, this is the first reported co-occurrence of these syndromes.

Cartilage oligomeric matrix protein (COMP), an extracellular matrix protein, has been shown to enhance proliferation and mechanical integrity in the matrix, supporting functions of the growth plate and articular cartilage. Mutations in COMP cause pseudoachondroplasia (PSACH), a severe dwarfing condition associated with premature joint degeneration and significant lifelong joint pain. The MT (mutant)-COMP mouse mimics PSACH with decreased limb growth, early joint degeneration and pain. Ablation of endoplasmic reticulum stress CHOP signaling eliminated pain and prevented joint degeneration. The health effects of mutant COMP are discussed in relation to cellular/chondrocyte stress in the growth plate, articular cartilage and nearby tissues, and the implications for therapeutic approaches. There are many similarities between osteoarthritis and mutant-COMP protein-induced joint degeneration, suggesting that the relevance of findings in the joints may extend beyond PSACH to idiopathic primary OA. [Display omitted] • Our MT-COMP mouse mimics pseudoachondroplasia with decreased limb growth, early joint degeneration, and pain. • Interrupting CHOP ER stress signaling (genetic ablation of CHOP) in MT-COMP eliminated pain, prevented joint degeneration, and dampened chondrocyte stress. • Osteoarthritis (OA) and mutant-COMP-induced joint degeneration share many stress processes including ER stress, inflammation, oxidative stress, dysregulated autophagy, and senescence suggesting our findings may extend to primary OA. [ABSTRACT FROM AUTHOR]

Background: Neurofibromatosis type 1 and pseudoachondroplasia are both rare autosomal dominant disorders, caused by pathogenic mutations in NF1 and COMP genes, respectively. Both neurofibromin 1 and cartilage oligomeric matrix protein (COMP) play a role in the development of the skeleton. Carrying both germline mutations has not been previously reported; however, it can affect the developing phenotype. Case presentation: The index patient, an 8-year-old female presented with several skeletal and dermatologic anomalies resembling the coexistence of multiple syndromes. Her mother had dermatologic symptoms characteristic for neurofibromatosis type 1, and her father presented with distinct skeletal anomalies. NGS-based analysis revealed a heterozygous pathogenic mutation in genes NF1 and COMP in the index patient. A previously unreported heterozygous variant was detected for the NF1 gene. The sequencing of the COMP gene revealed a previously reported, pathogenic heterozygous variant that is responsible for the development of the pseudoachondroplasia phenotype. Conclusions: Here, we present the case of a young female carrying pathogenic NF1 and COMP mutations, diagnosed with two distinct heritable disorders, neurofibromatosis type 1 and pseudoachondroplasia. The coincidence of two monogenic autosomal dominant disorders is rare and can pose a differential diagnostic challenge. To the best of our knowledge, this is the first reported co-occurrence of these syndromes. [ABSTRACT FROM AUTHOR]

Purpose: Pseudoachondroplasia is a rare skeletal dysplasia caused by a mutation in the COMP gene. Infants with pseudoachondroplasia present with rhizomelic dwarfism. Pseudoachondroplasia can resemble achondroplasia, which also presents with a phenotype of rhizomelic dwarfism. The differentiation between these two conditions is important because while both can present with cervicomedullary compromise, the underlying pathophysiology and its management is entirely different., Results: We present a case of a 13-year-old female patient with pseudoachondroplasia who presented with cervical myelopathy and imaging evidence of atlantoaxial instability with an os odontoideum and a retro-odontoid cystic soft tissue mass, causing C1-2 canal stenosis and cervical cord compression. She underwent C1 decompression and C1-2 posterior cervical fixation. Post-operative imaging demonstrated improved alignment of the os odontoideum, and complete resolution of the retro-odontoid soft tissue mass. We contend that retro-odontoid masses are a marker of local C1-2 joint instability and restoration of atlanto-axial alignment with posterior fixation and fusion alone is likely to be sufficient for regression of the mass and associated compression., Conclusion: Pseudoachondroplasia can present with atlantoaxial instability and cervicomedullary compromise and with retro-odontoid masses. The differentiation from achondroplasia is crucially important for surgical decision-making and management should include surgical decompression and fixation., Competing Interests: Declarations. Competing Interests: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia type 1 (MED1) are two rare skeletal disorders caused by cartilage oligomeric matrix protein (COMP) variants. This study aims to analyze the genotype and phenotype of patients with COMP variants. Clinical information for 14 probands was collected; DNA was extracted from blood for COMP variant detection. Clinical manifestations and radiology scoring systems were established to evaluate the severity of each patient's condition. Serum COMP levels in PSACH patients and healthy subjects were measured. Thirty-nine patients were included, along with 12 PSACH probands and two MED1 probands. Disproportionate short stature, waddling gait, early-onset osteoarthritis and skeletal deformities were the most common features. The height Z-score of PSACH patients correlated negatively with age at evaluation (r = − 0.603, p = 0.01) and the clinical manifestation score (r = − 0.556, p = 0.039). Over 50% of the PSACH patients were overweight/obese. The median serum COMP level in PSACH patients was 16.75 ng/ml, which was significantly lower than that in healthy controls (98.53 ng/ml; p < 0.001). The condition of MED1 patients was better than that of PSACH patients. Four novel variants of COMP were detected: c.874T>C, c.1123_1134del, c.1531G>A, and c.1576G>T. Height Z-scores and serum COMP levels were significantly lower in patients carrying mutations located in calmodulin-like domains 6, 7, and 8. As the two phenotypes overlap to different degrees, PSACH and MED1 are suggested to combine to produce "spondyloepiphyseal dysplasia, COMP type". Clinical manifestations and radiology scoring systems, serum COMP levels and genotype are important for evaluating patient condition severity. [ABSTRACT FROM AUTHOR]

Dominantly inherited mutations in COMP gene encoding cartilage oligomeric matrix protein may cause two dwarfing skeletal dysplasias, milder multiple epiphyseal dysplasia (MED) and more severe pseudoachondroplasia (PSACH). We studied the phenotype and X-rays of 11 patients from 5 unrelated families with different COMP mutations. Whole exome and/or Sangers sequencing were used for molecular analyses. Four to ten X-ray images of hands hips, knees or spine were available for each patient for retrospective analyses. Eight patients with MED have mutation c.1220G>A and 3 children with PSACH mutations c.1359C>A, c.1336G>A, or the novel mutation c.1126G>T in COMP. Progressive failure in growth developed in all patients from early childhood and resulted in short stature < 3rd percentile in 7 patients and very short stature < 1st percentile in four. Most patients had joint pain since childhood, severe stiffness in shoulders and elbows but increased mobility in wrists. Six children had bowlegs and two had knock knees. In all patients, X-rays of hands, hips and knees showed progressive, age-dependent skeletal involvement more pronounced in the epiphyses of long rather than short tubular bones. Anterior elongation and biconvex configuration of vertebral bodies were more conspicuous for kids. Six children had correction of knees and two adults had hip replacement. Skeletal and joint impairment in patients with MED and PSACH due to COMP mutation start in early childhood. Although the clinical severity is mutation and age dependent, many symptoms represent a continuous phenotypic spectrum between both diseases. Most patients may benefit from orthopaedic surgeries.

Abstract Background Cartilage oligomeric matrix protein (COMP) is an important extracellular matrix protein primarily functioning in the musculoskeletal tissues and especially endochondral bone growth. Mutations in COMP cause the skeletal dysplasia pseudoachondroplasia (PSACH) that is characterized by short limbs and fingers, joint laxity, and abnormalities but a striking lack of skull and facial abnormalities. Methods This study examined both mice and humans to determine how mutant‐COMP affects face and skull growth. Results Mutant COMP (MT‐COMP) mice were phenotypically distinct. Snout length and skull height were diminished in MT‐COMP mouse and the face more closely resembled younger controls. Three‐dimensional facial measurements of PSACH faces showed widely spaced eyes, reduced lower facial height, and decreased nasal protrusion, which correlated with a more juvenile appearing face. Neither MT‐COMP mice nor PSACH individuals show midface hypoplasia usually associated with abnormal endochondral bone growth. MT‐COMP mice do show delayed endochondral and membranous skull ossification that normalizes with age. Conclusion Therefore, mutant‐COMP affects both endochondral and intramembranous bones of the skull resulting in a reduction of the nose and lower facial height in mice and humans, in addition to its well‐defined role in the growth plate chondrocytes.

Background: Cartilage oligomeric matrix protein (COMP) is an important extracellular matrix protein primarily functioning in the musculoskeletal tissues and especially endochondral bone growth. Mutations in COMP cause the skeletal dysplasia pseudoachondroplasia (PSACH) that is characterized by short limbs and fingers, joint laxity, and abnormalities but a striking lack of skull and facial abnormalities. Methods: This study examined both mice and humans to determine how mutant‐COMP affects face and skull growth. Results: Mutant COMP (MT‐COMP) mice were phenotypically distinct. Snout length and skull height were diminished in MT‐COMP mouse and the face more closely resembled younger controls. Three‐dimensional facial measurements of PSACH faces showed widely spaced eyes, reduced lower facial height, and decreased nasal protrusion, which correlated with a more juvenile appearing face. Neither MT‐COMP mice nor PSACH individuals show midface hypoplasia usually associated with abnormal endochondral bone growth. MT‐COMP mice do show delayed endochondral and membranous skull ossification that normalizes with age. Conclusion: Therefore, mutant‐COMP affects both endochondral and intramembranous bones of the skull resulting in a reduction of the nose and lower facial height in mice and humans, in addition to its well‐defined role in the growth plate chondrocytes. [ABSTRACT FROM AUTHOR]

Purpose In 1959, Maroteaux and Lamy initially designated pseudoachondroplasia as a distinct dysplasia different from achondroplasia the most common form of skeletal dysplasia. Pseudoachondroplasia is caused by a mutation in the collagen oligomeric matrix protein gene (COMP) gene on chromosome 19p13.1-p12 encoding the COMP. The COMP gene mutations result in rendering the articular and growth plate cartilages incapable of withstanding routine biomechanical loads with resultant deformity of the joints. The purpose of the study was to characterize the typical orthopaedic findings in pseudoachondroplasia. Methods The charts and radiographs of 141 patients with pseudoachondroplasia were analyzed. This cohort, to our knowledge, represents the largest group of patients describing the typical orthopaedic manifestations of pseudoachondroplasia. Results Patients with pseudoachondroplasia have normal craniofacial appearance with normal intelligence. Short stature is not present at birth and generally appears by two to four years of age. The condition is a form of spondyloepiphyseal dysplasia and the long bones are characterized by dysplastic changes in the epiphysis, metaphysis and vertebral bodies. Radiographically the long bones have altered the appearance and structure of the epiphyses with small irregularly formed or fragmented epiphyses or flattening. The metaphyseal regions of the long bones show flaring, widening or 'trumpeting'. The cervical (89%) and thoracic and lumbar vertebrae show either platyspondyly, ovoid, 'cod-fish' deformity or anterior 'beaking'. Kyphosis (28%), scoliosis (58%) and lumbar lordosis (100%) are commonly seen. The femoral head and acetabulum are severely dysplastic (100%). The knees show either genu valgum (22%), genu varum (56%) or 'windswept' deformity (22%). Conclusion Most commonly these distortions of the appendicular and the axial skeleton lead to premature arthritis particularly of the hips and often the knees not uncommonly in the 20- to 30-year-old age group. [ABSTRACT FROM AUTHOR]

Pseudoachondroplasia (PSACH) is a rare, dominant genetic disorder affecting bone and cartilage development, characterized by short-limb short stature, brachydactyly, loose joints, joint stiffness, and pain. The disorder is caused by mutations in the COMP gene, which encodes a protein that plays a role in the formation of collagen fibers. In this study, we present the clinical and genetic characteristics of PSACH in two Chinese families. Whole-exome sequencing (WES) analysis revealed two novel missense variants in the COMP gene: NM&#95;000095.3: c.1319G>T (p.G440V, maternal) and NM&#95;000095.3: c.1304A>T (p.D435V, paternal-mosaic). Strikingly, both the G440V and D435V mutations were located in the same T3 repeat motif and exhibited the potential to form hydrogen bonds with each other. Upon further analysis using Missense3D and PyMOL, we ascertained that these mutations showed the propensity to disrupt the protein structure of COMP, thus hampering its functioning. Our findings expand the existing knowledge of the genetic etiology underlying PSACH. The identification of new variants in the COMP gene can broaden the range of mutations linked with the condition. This information can contribute to the diagnosis and genetic counseling of patients with PSACH., Competing Interests: Author QL was employed by the company Zhejiang Biosan Biochemical Technologies Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Zhou, Chen, Liu, Yang, Xie and Peng.)

Abstract Cartilage oligomeric matrix protein (COMP) is a large pentameric glycoprotein that interacts with multiple extracellular matrix proteins in cartilage and other tissues. While, COMP is known to play a role in collagen secretion and fibrillogenesis, chondrocyte proliferation and mechanical strength of tendons, the complete range of COMP functions remains to be defined. COMPopathies describe pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED), two skeletal dysplasias caused by autosomal dominant COMP mutations. The majority of the mutations are in the calcium binding domains and compromise protein folding. COMPopathies are ER storage disorders in which the retention of COMP in the chondrocyte ER stimulates overwhelming cellular stress. The retention causes oxidative and inflammation processes leading to chondrocyte death and loss of long bone growth. In contrast, dysregulation of wild-type COMP expression is found in numerous diseases including: fibrosis, cardiomyopathy and breast and prostate cancers. The most exciting clinical application is the use of COMP as a biomarker for idiopathic pulmonary fibrosis and cartilage degeneration associated osteoarthritis and rheumatoid and, as a prognostic marker for joint injury. The ever expanding roles of COMP in single gene disorders and multifactorial diseases will lead to a better understanding of its functions in ECM and tissue homeostasis towards the goal of developing new therapeutic avenues. Highlights • COMP is an extracellular matrix protein and the fifth member of the thrombospondin gene family. • COMP facilitates collagen fibrillogenesis and chondrocyte proliferation. • Autosomal dominant mutations in COMP cause two skeletal dysplasias, pseudoachondroplasia and multiple epiphyseal dysplasia. • Dysregulated COMP expression is found in tissue fibrosis, breast and prostate cancer and cardiomyopathy. • COMP is a biomarker idiopathic pulmonary fibrosis and for cartilage degeneration in osteoarthritis and rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

Mutations in COMP (cartilage oligomeric matrix protein) cause severe long bone shortening in mice and humans. Previously, we showed that massive accumulation of misfolded COMP in the ER of growth plate chondrocytes in our MT-COMP mouse model of pseudoachondroplasia (PSACH) causes premature chondrocyte death and loss of linear growth. Premature chondrocyte death results from activation of oxidative stress and inflammation through the CHOP-ER pathway and is reduced by removing CHOP or by anti-inflammatory or antioxidant therapies. Although the mutant COMP chondrocyte pathologic mechanism is now recognized, the effect of mutant COMP on bone quality and joint health (laxity) is largely unknown. Applying multiple analytic approaches, we describe a novel mechanism by which the deleterious consequences of mutant COMP retention results in upregulation of miR-223 disturbing the adipogenesis - osteogenesis balance. This results in reduction in bone mineral density, bone quality, mechanical strength and subchondral bone thickness. These, in addition to abnormal patterns of ossification at the ends of the femoral bones likely contribute to precocious osteoarthritis (OA) of the hips and knees in the MT-COMP mouse and PSACH. Moreover, joint laxity is compromised by abnormally thin ligaments. Altogether, these novel findings align with the PSACH phenotype of delayed ossification and bone age, extreme joint laxity and joint erosion, and extend our understanding of the underlying processes that affect bone in PSACH. These results introduce a novel finding that miR-223 is involved in the ossification defect in MT-COMP mice making it a therapeutic target. [ABSTRACT FROM AUTHOR]

Skeletal dysplasias are a large group of rare diseases, with over 400 distinct entities recognised. Diagnosis is challenging, largely reflecting the rareness of individual conditions; yet collectively these disorders affect as many as 1:3000 individuals. The phenotypic diagnosis of skeletal dysplasia is based on careful clinical evaluation and, critically, on assessment of radiological appearances of the skeleton, which in most cases requires specialist expertise. Powerful modern genetic testing is transforming the approach to diagnosis of rare genetic disease, but does not obviate the need for accurate clinical and radiological evaluation. Management of children with skeletal dysplasias must pay attention to detection and prevention of potentially severe complications, particularly those involving compromise of the central nervous system, such as foramen magnum narrowing or atlanto-axial subluxation. Surgical management aims to treat these complications, but can also enhance function and in some cases address short stature. Targeted molecular treatments are emerging with potential to reverse these disorders, and are already transforming the lives of some children with debilitating diseases. We discuss 5 skeletal dysplasia conditions in more detail: Achondroplasia, Pseudoachondroplasia, Spondyloepiphyseal Dysplasia Congenita, Cartilage Hair Hypoplasia and Hypophosphatasia. [ABSTRACT FROM AUTHOR]

Skeletal dysplasia is a heterogeneous group of abnormalities affecting growth and development of bone and cartilage characterized by disproportionate shortening of the limbs and/or spine. A systematic radiographic approach combined with pertinent clinical details can help guide specific genetic testing and treatment. We provide a discussion and examples of a few common and notable skeletal dysplasias to help familiarize general, pediatric, and musculoskeletal radiologists who do not commonly encounter children with these entities in their daily practices. [ABSTRACT FROM AUTHOR]

Summary Pseudoachondroplasia and multiple epiphyseal dysplasia are genetic skeletal diseases resulting from mutations in cartilage structural proteins. Electron microscopy and immunohistochemistry previously showed that the appearance of the cartilage extracellular matrix (ECM) in targeted mouse models of these diseases is disrupted; however, the precise changes in ECM organization and the pathological consequences remain unknown. Our aim was to determine the effects of matrilin-3 and COMP mutations on the composition and extractability of ECM components to inform how these detrimental changes might influence cartilage organization and degeneration. Cartilage was sequentially extracted using increasing denaturants and the extraction profiles of specific proteins determined using SDS-PAGE/Western blotting. Furthermore, the relative composition of protein pools was determined using mass spectrometry for a non-biased semi-quantitative analysis. Western blotting revealed changes in the extraction of matrilins, COMP and collagen IX in mutant cartilage. Mass spectrometry confirmed quantitative changes in the extraction of structural and non-structural ECM proteins, including proteins with roles in cellular processes such as protein folding and trafficking. In particular, genotype-specific differences in the extraction of collagens XII and XIV and tenascins C and X were identified; interestingly, increased expression of several of these genes has recently been implicated in susceptibility and/or progression of murine osteoarthritis. We demonstrated that mutation of matrilin-3 and COMP caused changes in the extractability of other cartilage proteins and that proteomic analyses of Matn3 V194D, Comp T585M and Comp DelD469 mouse models revealed both common and discrete disease signatures that provide novel insight into skeletal disease mechanisms and cartilage degradation.

Introduction. Pseudoachondroplasia (PSACH) is an autosomal dominant osteochondrodysplasia due to mutations in the gene encoding cartilage oligomeric matrix protein. It is characterized by rhizomelic dwarfism, limb and vertebral deformity, joint laxity and early onset osteoarthrosis. We present the girl with the early expressed and severe PSACH born to clinically and radiographically unaffected parents. Case Outline. A 6.5-year-old girl presented with short-limbed dwarfism (body height 79.5 cm,

Pseudoachondroplastic dysplasia is a rare inherited disorder characterized by skeletal malformations resulting to short stature. These individuals are usually normal at birth but due to the abnormal skeletal growth or dysplasia, the skeleton becomes weakened and malformed. The skeletal deformities increase as the individual grows and gains weight. Affected individuals may have radiographic features simulating vitamin D deficiency. In addition, affected individuals may have spinal abnormalities including abnormally increased lumbar lordosis and kyphosis.This case is being presented because of its rarity and simulation of rickets in the growing young child. [ABSTRACT FROM AUTHOR]

Pseudoachondroplasia (PSACH; MIM no. 177170) is an autosomal dominant osteochondrodysplasia characterized by short-limb short stature, brachydactyly and early-onset osteoarthropathy. Typically, at approximately two years of age, the rate of growth falls below the standard growth curve, causing a moderately severe form of disproportionate short-limb short stature. The current study described the clinical and radiographic observations of six Chinese patients with PSACH, and identified two de novo novel missense mutations [p.Asp326Asn (c.976G>A) and c.1585A>G (p.Thr529Ala)] in cartilage oligomeric matrix protein (COMP) in the patients. The current study expanded the mutation spectrum of the COMP gene, and contributes to the understanding of phenotype/ genotype of COMP-associated diseases. [ABSTRACT FROM AUTHOR]

Pseudoachondroplasia is an autosomal dominant skeletal dysplasia that results in disproportionately short stature, severe brachydactyly with strikingly lax small joints, malalignments of the lower limbs, and characteristic radiological features. Although named ‘false achondroplasia’, the entity is a distinct condition, in which affected individuals are born with normal length and have a normal facies, but is often only recognised after the age of 2 years, when the disproportion and waddling gait become evident. We report on an affected South African father and daughter, and highlight their clinical and radiographic features.

Pseudoachondroplasia (PSACH) is a well-described autosomal dominant short limb dwarfing condition caused by mutations in the cartilage oligomeric matrix protein gene ( COMP). The most debilitating complication of the disorder is joint pain starting in childhood, the extent and severity of which is poorly defined. The aim of this study was to fully assess the pain and identify additional clinical complications affecting those with PSACH. An online survey was distributed to individuals with PSACH. Of the 77 surveys analyzed, 83% reported chronic pain starting as early as the newborn period. Pain was most frequently reported in weight bearing joints including the knees, hips, and back, and significantly interfered with their overall quality of life. For pain relief, patients with PSACH used a wide variety of treatments. However, patients reported only a 60% resolution of pain with their current treatments. An increase in other comorbidities was not found, specifically osteoporosis was not increased. This study documents for the first time that pain is the most common presenting symptom in PSACH and is often overlooked until short stature becomes obvious. The recognition of chronic pain as one of the earliest manifestations of PSACH is important to allow for prompt diagnosis. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Pseudoachondroplasia (PSACH) is a skeletal dysplasia characterized by disproportionate short stature, small hands and feet, abnormal joints and early onset osteoarthritis. PSACH is caused by mutations in thrombospondin-5 (TSP-5, also known as cartilage oligomeric matrix protein or COMP), a pentameric extracellular matrix protein primarily expressed in chondrocytes and musculoskeletal tissues. The thrombospondin gene family is composed of matricellular proteins that associate with the extracellular matrix (ECM) and regulate processes in the matrix. Mutations in COMP interfere with calcium-binding, protein conformation and export to the extracellular matrix, resulting in inappropriate intracellular COMP retention. This accumulation of misfolded protein is cytotoxic and triggers premature death of chondrocytes during linear bone growth, leading to shortened long bones. Both in vitro and in vivo models have been employed to study the molecular processes underlying development of the PSACH pathology. Here, we compare the strengths and weaknesses of current mouse models of PSACH and discuss how the resulting phenotypes may be translated to clinical therapies. [ABSTRACT FROM AUTHOR]

Abstract: A 2.75-year-old Chinese boy presented with typical clinical features of pseudoachondroplasia, including disproportionate short-limb short stature, brachydactyly, genu varus and waddling gait. Radiologically, tubular bones were short with widened metaphyses, irregular and small epiphyses; anterior tonguing or beaking of vertebral bodies were characteristic. DNA sequencing analysis of the COMP gene revealed a heterozygous mutation (c.1511G>A, p.Cys504Tyr) in the patient but his parents were unaffected without this genetic change. The missense mutation (c.1511G>A) was not found in 100 healthy controls and has not been reported previously. Our findings expand the spectrum of known mutations in COMP leading to pseudoachondroplasia. [Copyright &y& Elsevier]

This historical report focuses on the first clinical description of pseudoachondroplasia and its radiographic findings. Only half a century ago, pseudoachondroplasia was recognized as a genetic disorder with a distinct but variable phenotype of short stature, normal facial features, and progressive joint problems starting in adolescence. Radiologically, the disease is particularly intriguing because the patients appear normal at birth. The patients develop the typical gait disturbances when they begin to walk. Radiographs show the characteristic anterior tongue-shaped lumbar vertebral body changes that develop after the first year of life. This account presents the most well-known group of individuals affected by pseudoachondroplasia, the Ovitz family, who narrowly escaped death in the concentration camp of Auschwitz in 1944 because of SS physician Dr. Josef Mengele's fascination with dwarfs. It was not until 1995 that the underlying genetic defect in the COMP gene was identified on chromosome 19. [ABSTRACT FROM AUTHOR]