Biomedical subjects

William G Cole

Publications and source records attributed to William G Cole.

At least 19 recordsLinked to original sources

PubMed2006

HOXD10 M319K mutation in a family with isolated congenital vertical talus.

Congenital vertical talus (CVT) is a primary dislocation of the talonavicular joint that often occurs in neuromusculoskeletal syndromes, but may also be seen as an isolated abnormality. Six families with isolated CVT were ascertained. DNA was isolated from 21 affected individuals and 17 unaffected individuals from these families, as well as from five sporadic patients with CVT. Variable expressivity was noted in three families, manifesting as clubfoot in three individuals. Genome-wide linkage analysis generated a maximum two-point logarithm of odds score on chromosome 2q with D2S1353 (Zmax = 1.43 at theta(max) = 0.1), 17 Mb from the HOXD gene cluster. DNA from one affected individual of each family was subjected to mutational analysis of the HOXD10 gene. A single missense mutation was identified (M319K, 956T > A) in the homeodomain recognition helix of the HOXD10 gene that segregated with disease in one large British family. This mutation was recently described in a family of Italian descent with CVT and Charcot-Marie-Tooth deformity HOXD10 gene mutations were not identified in any of the other families or sporadic patients with CVT, suggesting that genetic heterogeneity underlies this disorder.

Chromosomes, Human, Pair 2↗

PubMed2006

Structural abnormalities of the cornea and lid resulting from collagen V mutations.

PURPOSE: Type V collagen forms heterotypic fibrils with type I collagen and accounts for 10% to 20% of corneal collagen. The purpose of this study was to define the ocular phenotype resulting from mutations in the type V collagen genes COL5A1 and COL5A2 and to study the pathogenesis of anomalies in a Col5a1-deficient mouse. METHODS: Seven patients with classic Ehlers-Danlos syndrome (EDS) due to COL5A1 haploinsufficiency and one with an exon-skipping mutation in COL5A2 underwent an ocular examination, corneal topography, pachymetry, and specular microscopy. A Col5a1-haploinsufficient mouse model of classic EDS was used for biochemical and immunochemical analyses of corneas. Light and electron microscopy were used to quantify stromal thickness, fibril density, fibril structure, and diameter. RESULTS: Five males and three females (mean age, 26 +/- 13.57 years; range, 11-52) were studied. All patients had "floppy eyelids." The corneas of all eyes were thinner (mean corneal thickness: 435.75 +/- 12.51 microm) when compared with control corneas (568.89 +/- 28.46 microm; P < 0.0001). In the Col5a1+/- mouse cornea, type V collagen content was reduced by approximately 49%, and stromal thickness was reduced by approximately 26%. Total collagen deposition in Col5a1(+/-) corneas also was reduced. Collagen fibril diameters were increased, but fibril density was decreased throughout the stroma at all developmental stages. CONCLUSIONS: In the eye, COL5A1 and COL5A2 mutations manifest as abnormally thin and steep corneas with floppy eyelids. Mechanisms involved in producing the latter anomalies probably involve altered regulation of collagen fibrillogenesis due to abnormalities in heterotypic type I/V collagen interactions similar to those observed in the Col5a1+/- mouse cornea.

Adolescent↗

PubMed2006

Factors predicting the outcome of primary clubfoot surgery.

BACKGROUND: We aimed to determine the rate of further surgery, the functional outcome and the factors associated with outcome after primary clubfoot surgery. METHOD: We conducted a retrospective study of a cohort of all children who were less than 2 years of age at the time of surgery for idiopathic clubfoot deformity at the Hospital for Sick Children, Toronto, Ont., a tertiary care pediatric hospital. Of the 91 families who could be contacted, 63 agreed to return. The children's charts were reviewed, and their feet were given a Functional Rating System (FRS) score. RESULTS: Of the original operated population (n = 126), 75% were male and 41% had bilateral clubfoot. The average age at the time of surgery was 8 months, and the mean follow-up was 80.6 months. Further surgery was performed in 19% of cases. The mean FRS outcome score was 79. On average, the FRS score increased by 1.9 points as age at the time of surgery increased by 1 month. Only the presurgical talocalcaneal index was associated with the need for further surgery. CONCLUSION: The need for further surgery was 19% overall. Children who had surgery closer to 12 months of age had better functional results. Therefore, surgery should probably be performed in the second, rather than the first, 6 months of life.

Child↗

PubMed2005

Schmid type of metaphyseal chondrodysplasia and COL10A1 mutations--findings in 10 patients.

The Schmid type of metaphyseal chondrodyplasia (MCDS) is characterized by short stature, widened growth plates, and bowing of the long bones. It results from autosomal dominant mutations of COL10A1, the gene which encodes alpha1(X) chains of type X collagen. We report the clinical and radiographic findings in 10 patients with MCDS and COL10A1 mutations. Six patients had lower limb deformities, which necessitated orthopedic surgeries in all of them. One patient demonstrated no deformities and normal stature at age 11 years (height -1.2 SDS) while the others manifested severe short stature (<-3.5 SDS). Radiographs showed metaphyseal changes which were most pronounced at the hips and knees. Five of the identified 10 mutations in COL10A1 were novel. Six mutations resulted in truncation of the NC1 domain while four mutations were single amino-acid substitutions. Our findings suggest that COL10A1 mutations result in a uniform pattern of growth plate abnormalities. However, the clinical variability in severity among affected individuals is greater than previously thought.

Adolescent↗

PubMed2005

Improvements in advance care planning in the Veterans Affairs System: results of a multifaceted intervention.

BACKGROUND: Advance care planning (ACP) aims to guide health care in the event of decisional incapacity. Interventions to promote ACP have had limited effectiveness. We conducted an educational and motivational intervention in Department of Veterans Affairs outpatient clinics to increase ACP use and proxy and health care provider understanding of patients' preferences and values. METHODS: We recruited 23 providers and up to 14 of each of their patients; the patients were randomized to the control or intervention group. Eligibility criteria included a preexisting relationship with the provider, age 55 years or older, chronic health condition(s), and no recorded advance directive. The intervention group (n = 119) received an ACP workbook, motivational counseling by social workers, and cues to providers to discuss ACP. The control group (n = 129) received an advance directive booklet. RESULTS: The intervention patients reported more ACP discussions with their providers (64% vs 38%; P<.001). Living wills were filed in the medical record twice as often in the intervention group (48% vs 23%; P<.001). Provider-patient dyads in the intervention group had higher agreement scores than the control group for treatment preferences, values, and personal beliefs (58% vs 48%, 57% vs 46%, and 61% vs 47%, respectively; P<.01 for all comparisons). The agreement scores for the proxy-patient dyads did not differ between groups for treatment preferences and values, but were higher in the intervention than the control group for personal beliefs (67% vs 56%). CONCLUSION: This intervention demonstrates mixed results and highlights the ongoing challenges of helping health care providers and potential proxy decision makers represent patient preferences and values.

Advance Care Planning↗

PubMed2005

Heterozygous mutations in the LDL receptor-related protein 5 (LRP5) gene are associated with primary osteoporosis in children.

UNLABELLED: Three of 20 patients with juvenile osteoporosis were found to have a heterozygous mutation in the LRP5 gene. No mutations were found in the type I collagen genes. Mutations in the other family members with similar bone phenotype confirmed that LRP5 has a role in both juvenile and adult osteoporosis. INTRODUCTION: The gene encoding the low-density lipoprotein receptor-related protein 5 (LRP5) gene has recently been shown to affect bone mass accrual during growth and to be involved in osteoporosis-pseudoglioma syndrome and a high bone mass phenotype. Mutations in the type I collagen genes (COL1A1 and COL1A2) are known to cause osteogenesis imperfecta, characterized by increased bone fragility. MATERIALS AND METHODS: Here we analyzed COL1A1, COL1A2, and LRP5 for mutations in 20 pediatric patients with primary osteoporosis characterized by low BMD, recurrent fractures, and absent extraskeletal manifestations. RESULTS AND CONCLUSIONS: No mutations were detected in the type I collagen genes, but two missense mutations (A29T and R1036Q) and one frameshift mutation (C913fs) were found in the LRP5 gene in three of the patients. The frameshift mutation was also seen in the proband's father and brother, who both were found to have significant osteoporosis. R1036Q was observed in the proband's mother and two brothers, who all had osteoporosis. These results indicate that heterozygous mutations in the LRP5 gene can cause osteoporosis in both children and adults.

Adolescent↗

PubMed2005

Multiple epiphyseal dysplasia mutations in MATN3 cause misfolding of the A-domain and prevent secretion of mutant matrilin-3.

Multiple epiphyseal dysplasia (MED) is a relatively common skeletal dysplasia that can present in childhood with a variable phenotype of short stature and pain and stiffness in the large joints, and often progresses to early-onset osteoarthritis in adulthood. Mutations in the matrilin-3 gene (MATN3) have recently been shown to underlie some forms of autosomal dominant MED. To date all MED mutations in matrilin-3 cluster in the single A-domain, suggesting that they may disrupt the structure and/or function of this important domain. To determine the effects of MATN3 mutations on the structure and function of matrilin-3 we expressed both normal and mutant matrilin-3 in mammalian cells. Wild-type (wt) matrilin-3 was efficiently secreted into conditioned medium, whereas mutant matrilin-3 was retained and accumulated within the cell. Furthermore, when the mutant A-domains were examined individually, they existed primarily in an unfolded conformation. Co-immunoprecipitation experiments demonstrated that the mutant A-domains were specifically associated with ERp72, a chaperone protein known to be involved in mediating disulfide bond formation. Light microscopy of cartilage from an MED patient with a MATN3 mutation showed the presence of intracellular material within the chondrocytes, whilst the overall matrix appeared normal. On electron micrographs, the inclusions noted at the light microscopy level appeared to be dilated cisternae of rough endoplasmic reticulum and immunohistochemical analysis confirmed that the retained protein was matrilin-3. In summary, the data presented in this paper suggest that MED caused by MATN3 mutations is the result of an intracellular retention of the mutant protein.

Animals↗

PubMed2005

Radiographic vertebral morphology: a diagnostic tool in pediatric osteoporosis.

OBJECTIVE: To assess the value of spinal radiographs in determining the significance of reductions in bone mass or density in chronically ill children. STUDY DESIGN: A pediatric scoring method for assessment of osteoporotic vertebral changes, developed on the basis of radiographs of 70 healthy controls and established adult scoring methods, was subsequently used to assess 32 pediatric patients with suspected secondary osteoporosis. Radiographic findings were correlated with bone mineral density (BMD), clinical data, and biochemistry. RESULTS: Thirty-two patients (median age 14.1 years) were included. Assessment of spinal radiographs with the developed scoring method found previously undiagnosed spinal compression deformities in 11 patients (34%) of whom 9 were asymptomatic and 8 had lumbar spine (size-corrected) BMD measurements within +/-2.0 SD of the age- and sex-specific norms. Fracture history and cumulative glucocorticoid (GC) dose did not differ between those with and without compression deformities. CONCLUSIONS: Vertebral compression fractures can be documented in a significant number of chronically ill children and are poorly predicted by single BMD measurements and clinical history. Assessment of vertebral morphology is recommended as an additional tool in the diagnostic workup of pediatric osteoporosis.

Absorptiometry, Photon↗

PubMed2005

Mutations in the known genes are not the major cause of MED; distinctive phenotypic entities among patients with no identified mutations.

Multiple epiphyseal dysplasia (MED) is a clinically and genetically heterogeneous chondrodysplasia. Mutations in six genes (COMP, COL9A1, COL9A2, COL9A3, MATN3 and DTDST) have been reported, but the genotype-phenotype correlations and the proportions of cases due to mutations in these genes are still not well characterized. We performed a clinical, radiological and molecular analysis of known MED genes on 29 consecutive MED patients. The mutation analysis resulted in identification of the DTDST mutation in four patients (14%), the COMP mutation in three (10%) and the MATN3 mutation in three (10%). Thus, a disease-causing mutation was identified in 10 patients altogether (34%). The phenotypic features observed in the patients with mutations were in accordance with previously described phenotypes, but two new distinct phenotypic entities were identified in patients in whom no mutation was found. One of them was characterized by severe, early-onset dysplasia of the proximal femurs with almost complete absence of the secondary ossification centres and abnormal development of the femoral necks. The other phenotype was characterized by 'mini-epiphyses', resulting in severe dysplasia of the proximal femoral heads. The findings suggest that mutations in the known genes are not the major cause of MED and are responsible for less than half of the cases. The existence of additional MED loci is supported by the exclusion of known loci by mutation analysis and finding of specific subgroups among these patients.

Adolescent↗

PubMed2005

Differentiation-induced loss of heparan sulfate in human exostosis derived chondrocytes.

An exostosis or osteochondroma is an aberrant bony growth occurring next to the growth plate either as an isolated growth abnormality or as part of the Hereditary Multiple Exostosis (HME) syndrome. Mutations in either exostosin 1 (EXT1) or exostosin 2 (EXT2) gene cause the HME syndrome and also some isolated osteochondromas. The EXT1 and EXT2 genes are glycosyltransferases that function as hetero-oligomers in the Golgi to add repeating glycosaminoglycans (GAGs) to heparan sulfate (HS) chains. Previously, we demonstrated that HS is markedly diminished in the exostosis cartilage cap and that the HS proteoglycan, perlecan, has an abnormal distribution in these caps. The present studies were undertaken to evaluate which chondrocyte-specific functions are associated with diminished HS synthesis in human chondrocytes harboring either EXT1 or EXT2 mutations. Systematic evaluation of exostosis cartilage caps and chondrocytes, both in vitro and in vivo, suggests that chondrocyte-specific cell functions account for diminished HS levels. In addition, we provide evidence that perichondrial cells give rise to chondrocytes that clonally expand and develop into an exostosis. Undifferentiated EXT chondrocytes synthesized amounts of HS similar to control chondrocytes; however, EXT chondrocytes displayed very poor survival in vitro under conditions that promote normal chondrocyte differentiation with high efficiency. Collectively, these observations suggest that loss of one copy of either the EXT1 or EXT2 gene product compromises the perichondrial chondrocytes' ability to differentiate normally and to survive in a differentiated state in vitro. In vivo, these compromised responses may lead to abnormal chondrocyte growth, perhaps from a perichondrial stem cell reserve.

Cell Differentiation↗

PubMed2005

A novel COL1A1 mutation in infantile cortical hyperostosis (Caffey disease) expands the spectrum of collagen-related disorders.

Infantile cortical hyperostosis (Caffey disease) is characterized by spontaneous episodes of subperiosteal new bone formation along 1 or more bones commencing within the first 5 months of life. A genome-wide screen for genetic linkage in a large family with an autosomal dominant form of Caffey disease (ADC) revealed a locus on chromosome 17q21 (LOD score, 6.78). Affected individuals and obligate carriers were heterozygous for a missense mutation (3040Ctwo head right arrowT) in exon 41 of the gene encoding the alpha1(I) chain of type I collagen (COL1A1), altering residue 836 (R836C) in the triple-helical domain of this chain. The same mutation was identified in affected members of 2 unrelated, smaller families with ADC, but not in 2 prenatal cases and not in more than 300 chromosomes from healthy individuals. Fibroblast cultures from an affected individual produced abnormal disulfide-bonded dimeric alpha1(I) chains. Dermal collagen fibrils of the same individual were larger, more variable in shape and size, and less densely packed than those in control samples. Individuals bearing the mutation, whether they had experienced an episode of cortical hyperostosis or not, had joint hyperlaxity, hyperextensible skin, and inguinal hernias resembling symptoms of a mild form of Ehlers-Danlos syndrome type III. These findings extend the spectrum of COL1A1-related diseases to include a hyperostotic disorder.

Bone and Bones↗

PubMed2005

Congenital dislocation of the patella.

OBJECTIVE: Our objective was to present the imaging findings for congenital dislocation of the patella, an uncommon condition with variable clinical manifestations in patients of different ages. CONCLUSION: Sonography can clearly illustrate the presence and location of the laterally displaced patella and the anatomy of adjacent joint structures. The high resolution for soft-tissue, cartilaginous, and bony structures of the immature skeleton makes sonography a valuable tool in the management of congenital dislocation of the patella. Conventional radiography is a simple method for diagnosis once ossification of the patella has commenced and for postoperative follow-up. MRI allows visualization of fine anatomic details and relationships between the involved structures of the extensor mechanism and is the technique of choice for preoperative planning.

Child, Preschool↗

PubMed2004

COMP mutations, chondrocyte function and cartilage matrix.

Cartilage oligomeric matrix protein (COMP) is a large extracellular pentameric glycoprotein found in the territorial matrix surrounding chondrocytes. More than 60 unique COMP mutations have been identified as causing two skeletal dysplasias, pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED/EDM1). Recent studies demonstrate that calcium-binding and calcium induced protein folding differ between wild type and mutant COMP proteins and abnormal processing of the mutant COMP protein causes the characteristic large lamellar appearing rough endoplasimic reticulum (rER) cisternae phenotype observed in PSACH and EDMI growth plate chondrocytes. To understand the cellular events leading to this intracellular phenotype, PSACH chondrocytes with a G427E, D469del and D511Y mutations were grown in 3-D culture to produce cartilage nodules. Each nodule was assessed for the appearance and accumulation of cartilage-specific proteins within the rER and for matrix protein synthesis. All three COMP mutations were associated with accumulation of COMP in the rER cisternae by 4 weeks in culture, and by 8 weeks the majority of chondrocytes had the characteristic cellular phenotype. Mutations in COMP also affect the secretion of type IX collagen and matrilin-3 (MATN3) but not the secretion of aggrecan and type II collagen. COMP, type IX collagen and MATN3 were dramatically reduced in the PSACH matrices, and the distribution of these proteins in the matrix was diffuse. Ultrastructural analysis shows that the type II collagen present in the PSACH matrix does not form organized fibril bundles and, overall, the matrix is disorganized. The combined absence of COMP, type IX collagen and MATN3 causes dramatic changes in the matrix and suggests that these proteins play important roles in matrix assembly.

Calcium↗

PubMed2004

Reduced type I collagen utilization: a pathogenic mechanism in COL5A1 haplo-insufficient Ehlers-Danlos syndrome.

To examine mechanisms by which reduced type V collagen causes weakened connective tissues in the Ehlers-Danlos syndrome (EDS), we examined matrix deposition and collagen fibril morphology in long-term dermal fibroblast cultures. EDS cells with COL5A1 haplo-insufficiency deposited less than one-half of hydroxyproline as collagen compared to control fibroblasts, though total collagen synthesis rates are near-normal because type V collagen represents a small fraction of collagen synthesized. Cells from patients with osteogenesis imperfecta (OI) and haplo-insufficiency for proalpha1(I) chains of type I collagen also incorporated about one-half the collagen as controls, but this amount was proportional to their reduced rates of total collagen synthesis. Collagen fibril diameter was inversely proportional to type V/type I collagen ratios (EDS > control > OI). However, a reduction of type V collagen, in the EDS derived cells, was associated with the assembly of significantly fewer fibrils compared to control and OI cells. These data indicate that in cell culture, the quantity of collagen fibrils deposited in matrix is highly sensitive to reduction in type V collagen, far out of proportion to type V collagen's contribution to collagen mass.

Cell Culture Techniques↗

PubMed2004

Clinical and radiographic findings in multiple epiphyseal dysplasia caused by MATN3 mutations: description of 12 patients.

Multiple epiphyseal dysplasia (MED) is characterized by pain and stiffness in joints and delayed and irregular ossification of epiphyses. Causative mutations have been recognized in six different genes. We have identified disease-causing mutations in the gene encoding matrilin-3, an extracellular matrix protein, in seven families with autosomal dominant MED. Review of the clinical and radiographic features in 12 of the affected family members shows a uniform pattern of skeletal anomalies in all patients with considerable degree of variability in severity, both between and within families. The characteristic clinical findings are onset of symptoms in early childhood with predominance of knee and hip related complaints, normal stature, and early-onset osteoarthritis. Radiographs show small and irregular epiphyses and mild metaphyseal irregularities and striations, especially at the knees and hips and mild spinal changes. Despite overlap, both clinically and radiographically, with other forms of MED, the described features may help to differentiate this particular form from other entities within the MED spectrum.

Adolescent↗

PubMed2004

Impairment and activity limitation associated with epiphyseal dysplasia in children.

OBJECTIVES: To develop a profile of impairment and activity limitation among children with epiphyseal dysplasia (ED) and to identify the relationship between these 2 domains. DESIGN: Cross-sectional study. SETTING: Acute, pediatric academic and health sciences center. PARTICIPANTS: Eleven subjects with multiple epiphyseal dysplasia (MED) and 17 subjects with spondyloepiphyseal dysplasia (SED), with a mean age of 12.9 years. INTERVENTIONS: Not applicable. Main outcome measures Anthropometric indexes of growth and nutrition, joint range of motion (ROM) and alignment, muscle strength, pain, and activity limitation. RESULTS: Subjects with SED had significantly shorter stature than the reference population (P<.01). Seventy-three percent of participants with MED and 77% of those with SED were above average or overweight for their height (P<.01). Both groups presented with moderate to severe joint ROM impairment, with greater lower-extremity involvement. Subjects with SED had worse outcomes with respect to overall ROM and alignment impairments (P<.01), particularly in their upper extremities (P<.01), than subjects with MED. Significant overall muscle weakness was noted in all subjects (z=-1.81; P<.01). Ninety-four percent of subjects with SED reported pain with activity, compared with 64% of those with MED (P=.04), although pain intensity did not differ between groups. Fifty percent of subjects had undergone orthopedic surgery. Mild activity limitation was reported by all subjects (mean score, 87.7+/-18.83). Significant correlations were identified between height for age and strength (r=.50) and pain and activity limitation (r=-.50). CONCLUSIONS: Despite moderate to severe impairments, all subjects reported surprisingly mild activity limitation. A positive correlation was identified between pain and activity limitation. This study also identified and described patterns of muscle weakness, pain, and nutritional concerns not previously reported in the ED literature.

Adolescent↗

PubMed2004

Cell-type specific trafficking of expressed mutant COMP in a cell culture model for PSACH.

Pseudoachondroplasia (PSACH) is an autosomal dominant disease that mainly affects cartilage, resulting in skeletal dysplasias and early onset osteoarthritis. PSACH is caused by mutations in the cartilage oligomeric matrix protein (COMP) gene. PSACH chondrocytes accumulate unique COMP-containing lamellar structures in an expanded rough endoplasmic reticulum (rER). Although COMP is also present in tendon extracellular matrix (ECM), it does not accumulate in PSACH tendon cells, suggesting the disease involves a chondrocyte-specific trafficking problem. To investigate putative cell-specific trafficking differences, we generated a cell culture model utilizing expression of the common DeltaD469 COMP mutation. In rat chondrosarcoma (RCS) cells, we find delayed secretion and ER accumulation of DeltaD469 COMP, paralleling the altered trafficking defect in PSACH chondrocytes. Non-chondrocytic COS-1 cells, in contrast, efficiently trafficked and secreted both mutant and wild-type COMP. In chondrocytic cells, expression of DeltaD469 COMP led to ER accumulation of type IX collagen, but did not affect aggrecan trafficking. Endogenous rat COMP accumulated in the ER along with expressed DeltaD469 COMP in a stably expressing RCS clone, consistent with the dominant negative effect of PSACH. When these stably expressing cells were cultured to promote ECM deposition, the small amount of secreted mutant COMP disrupted assembly of the normal fibrillar meshwork and caused irregular aggregates of COMP and type IX collagen to form. Thus, in a new model that reflects the cellular pathology of PSACH, we establish trafficking differences for mutant COMP in chondrocytic and non-chondrocytic cells and demonstrate that mutant COMP interferes with assembly of a normal ECM.

Achondroplasia↗

PubMed2004

Chondrocyte cell death and intracellular distribution of COMP and type IX collagen in the pseudoachondroplasia growth plate.

Cartilage oligomeric matrix protein (COMP) is a large extracellular matrix protein expressed in cartilage, ligament and tendon. Mutations in the COMP gene cause two dominantly inherited skeletal dysplasias, pseudoachondroplasia (PSACH) and Multiple Epiphyseal Dysplasia (MED/EDM1). We report on a novel point mutation D511Y in the seventh calcium-binding repeat of the COMP gene and the resulting iliac crest growth plate pathology. The PSACH iliac crest growth plate is comprised of a large region of resting chondrocytes above a narrow region composed of clusters of disorganized proliferative and hypertrophic chondrocytes. Chondrocytes in all zones show massive intracellular retention of COMP and the surrounding extracellular matrix is deficient in COMP. Moreover, the 511Y COMP mutation selectively affects type IX collagen as little is found in the growth plate matrix whereas type II collagen and aggrecan are abundant in the matrix. Chondrocyte remnants are observed in the chondrocyte clusters and dead cells are found throughout the growth plate. Apoptosis studies demonstrate an unusual pattern of TUNEL staining in the PSACH chondrocytes compared to the control growth plate. These in vivo findings support our previous observation that retention of COMP leads to chondrocyte death. These results also add to the increasing evidence that PSACH and EDM1 are rER storage diseases and that impaired linear growth and joint erosion are caused by the disruptive effect of massive amounts of COMP within the chondrocytes.

Achondroplasia↗