Clinical and Genetic Characteristics of COL2A1-Associated Skeletal Dysplasias in 60 Russian Patients: Part I.

The significant variability in the clinical manifestations of COL2A1-associated skeletal dysplasias makes it necessary to conduct a clinical and genetic analysis of individual nosological variants, which will contribute to improving our understanding of the pathogenetic mechanisms and prognosis. We presented the clinical and genetic characteristics of 60 Russian pediatric patients with type II collagenopathies caused by previously described and newly identified variants in the COL2A1 gene. Diagnosis confirmation was carried out by new generation sequencing of the target panel with subsequent validation of the identified variants using automated Sanger sequencing. It has been shown that clinical forms of spondyloepiphyseal dysplasias predominate in childhood, both with more severe clinical manifestations (58%) and with unusual phenotypes of mild forms with normal growth (25%). However, Stickler syndrome, type I was less common (17%). In the COL2A1 gene, 28 novel variants were identified, and a total of 63% of the variants were found in the triple helix region resulted in glycine substitution in Gly-XY repeats, which were identified in patients with clinical manifestations of congenital spondyloepiphyseal dysplasia with varying severity, and were not found in Stickler syndrome, type I and Kniest dysplasia. In the C-propeptide region, five novel variants leading to the development of unusual phenotypes of spondyloepiphyseal dysplasia have been identified.

Clinical and Molecular Characterization and Discovery of Novel Genetic Mutations of Chinese Patients with COL2A1-related Dysplasia.

COL2A1-related disorders represent a heterogeneous group of skeletal dysplasias with a wide phenotypic spectrum. Our aim is to characterize the clinical and molecular phenotypes of Chinese patients with COL2A1-related dysplasia and to explore their phenotype-genotype relations. Clinical data were collected, physical examinations were conducted, and X-ray radiography and genetic analyses were performed in ten families involving 29 patients with COL2A1-related dysplasia. Nine mutations were identified in COL2A1, including five novel (c.816+6C>T, p.Gly246Arg, p.Gly678Glu, p.Gly1014Val and p.Ter1488Gln) and four reported previously (p.Gly204Val, p.Arg275Cys, p.Gly504Ser and p.Arg719Cys). Based on clinical features and molecular mutations, the ten families were classified into five definite COL2A1-related disorders: four families with spondyloepiphyseal dysplasia congenita (SEDC), three with osteoarthritis with mild chondrodysplasia (OSCPD), one with Czech dysplasia, one with Kniest dysplasia, and one with epiphyseal dysplasia, multiple, with myopia and deafness (EDMMD). Based on genetic testing results, prenatal diagnosis and genetic counseling were accomplished for one female proband with OSCDP. Chinese patients with OSCDP, Czech dysplasia and EDMMD caused by COL2A1 mutations were first reported, expanding the spectrum of COL2A1 mutations and the phenotype of COL2A1-related disorders and providing further evidence for the phenotype-genotype relations, which may help improve procreative management of COL2A1-related disorders.

Expression of the receptor for advanced glycation end products in acquired reactive perforating collagenosis.

BACKGROUND: Acquired reactive perforating collagenosis (ARPC) is a rare skin disorder characterized by transepidermal elimination of dermal collagen. There is little data regarding the pathogenesis of ARPC. The receptor for advanced glycation end products (RAGE) is a multiligand transmembrane receptor that plays an important role in inflammatory responses and may be involved in the pathogenesis of ARPC. AIM: To explore the expression of RAGE in ARPC. METHODS: Paraffin-embedded punch biopsy specimens of 41 patients with ARPC and of 11 healthy controls with normal skin were obtained from the Department Of Pathology. Clinical data of all patients were reviewed from the medical files. All specimens were stained immunohistochemically with antibody to RAGE (Anti-RAGE). The intensity of RAGE expression was assessed semi-quantitatively on epidermal cells, microvascular endothelium, dermal fibroblasts and inflammatory cells and graded as 0 (no staining), 1 (weak), 2 (moderate) and 3 (strong). The patients were divided into diabetic and nondiabetic groups for analysis. RESULTS: RAGE expression in microvascular endothelium, inflammatory cells and fibroblasts of patients with ARPC was more intense than normal tissues of healthy participants (P values are 0.005, 0.017 and P > 0.05). LIMITATIONS: Our method of assessment of RAGE expression was semi-quantitative. CONCLUSION: We observed an overexpression of RAGE in lesional samples of patients with ARPC which was independent of the presence of diabetes.

Malformação venosa associada a hiperelasticidade cutânea e atrofia do tecido subcutâneo / Venous malformation associated with skin hyperelasticity and subcutaneous atrophy

A rigidez da parede venosa pode aumentar em síndromes em que há uma redução da quantidade de elastina, ocasionando malformações venosas mesmo em indivíduos que possuem mosaicismo para tais síndromes. Casos com apresentação de afecções colagenosas em áreas delimitadas não foram descritos na literatura. O paciente apresentava lesão bem delimitada em região anteromedial da coxa com aumento de elasticidade e presença de vasos tortuosos apenas no local da lesão, não apresentando nenhuma síndrome colagenosa. Foi realizada uma biópsia que evidenciou alterações em relação ao padrão das fibras elásticas e proliferação de vasos sanguíneos. A malformação venosa foi tratada satisfatoriamente com embolização. As doenças do colágeno causam hiperextensibilidade cutânea, o que provoca flacidez e propicia traumas. As colagenoses bem delimitadas são raras, pois geralmente esse grupo de doenças envolve acometimento sistêmico. As malformações vasculares podem ocorrer em diversas doenças do colágeno, mas de forma generalizada e não localizada, e uma explicação para isso seria o mosaicismo genético.

In syndromes that involve reduced quantities of elastin, the rigidity of vein walls may be increased, causing venous malformations, even in people who have mosaicism for these syndromes. There are no previous descriptions in the literature of collagen diseases presenting in specific, delimited areas. The patient described here presented with a lesion restricted to a well-defined area of the anteromedial thigh, in which elasticity was increased and vessels were tortuous, in the area of the lesion only, and with no other signs of collagen syndromes. A biopsy was conducted and the findings included changes to the normal arrangement of the elastic fibers and proliferation of blood vessels. The venous malformation was treated satisfactorily by embolization. Collagen diseases can cause cutaneous hyperextensibility, provoking flaccidity and a propensity to traumatisms. Connective tissue diseases restricted to well-delimited areas are rare, since this group of diseases usually has systemic involvement. Vascular malformations can be seen in many different collagen diseases, but with generalized rather than localized presentation. One possible explanation for the case described here is genetic mosaicism.

The expanding spectrum of COL2A1 gene variants IN 136 patients with a skeletal dysplasia phenotype.

Heterozygous COL2A1 variants cause a wide spectrum of skeletal dysplasia termed type II collagenopathies. We assessed the impact of this gene in our French series. A decision tree was applied to select 136 probands (71 Stickler cases, 21 Spondyloepiphyseal dysplasia congenita cases, 11 Kniest dysplasia cases, and 34 other dysplasia cases) before molecular diagnosis by Sanger sequencing. We identified 66 different variants among the 71 positive patients. Among those patients, 18 belonged to multiplex families and 53 were sporadic. Most variants (38/44, 86%) were located in the triple helical domain of the collagen chain and glycine substitutions were mainly observed in severe phenotypes, whereas arginine to cysteine changes were more often encountered in moderate phenotypes. This series of skeletal dysplasia is one of the largest reported so far, adding 44 novel variants (15%) to published data. We have confirmed that about half of our Stickler patients (46%) carried a COL2A1 variant, and that the molecular spectrum was different across the phenotypes. To further address the question of genotype-phenotype correlation, we plan to screen our patients for other candidate genes using a targeted next-generation sequencing approach.

Association between Kniest dysplasia and chondrosarcoma in a child.

Constitutive COL2A1 mutations are associated with a wide variety of clinical manifestations known as type II collagenopathies. Among them is Kniest dysplasia, which is phenotypically variable and includes both skeletal (short trunk and limbs, kyphoscoliosis, prominent joints, and osteoarthritis) and craniofacial characteristics. Kniest dysplasia mutations primarily arise in the triple-helicoidal region of the alpha 1 (II) chain in COL2A1 between exons 12 and 24. Somatic COL2A1 mutations have been identified in chondrosarcoma, a rare cartilage forming neoplasm, with a hypermutability of the gene reported in 37% of cases. However, to the best of our knowledge, there is no reported increase in predisposition to chondrosarcoma in human collagenopathies, and no reported clinical association between these congenital diseases and cartilaginous tumors. In the case study presented here, we report the first description of an association between these two rare diseases involving COL2A1, in a child presenting with Kniest dysplasia and a grade I sphenoethmoidal chondrosarcoma. We also describe a new constitutive mutation in COL2A1.

[Kniest dysplasia due to mutation of COL2A1 gene].

OBJECTIVE: To detect potential mutation of COL2A1 gene in two children suspected for Kniest dysplasia. METHODS: The 54 exons and splicing regions of the COL2A1 gene were amplified with PCR and the product was subjected to direct sequencing. RESULTS: A missense mutation (c.905C>T, p.Ala302Val) was found in the coding region of the COL2A1 gene, which has been previously reported in abroad. The patients appeared to have short trunk dwarfism, enlarged joints and midface hypoplasia. CONCLUSION: The probands are the first cases of Kniest dysplasia described in China, and so was the p.Ala302Val mutation.

Ophthalmic and molecular genetic findings in Kniest dysplasia.

PURPOSE: To study the variability of the ophthalmic phenotype in Kniest dysplasia. Kniest dysplasia is an inherited disorder associated with defects in type II collagen and characterised by short-trunked dwarfism, kyphoscoliosis, and enlarged joints with restricted mobility. Other features include marked hand arthropathy, cleft palate, hearing loss, and ocular abnormalities (myopia, abnormal vitreous, and high risk of developing retinal detachment). METHODS: Data from eight unrelated individuals with a clinical and molecular diagnosis of Kniest dysplasia are reported. Clinical assessment included an audiogram and ophthalmological examination in all but one patient who died in the immediate postnatal period. Sanger sequencing of the COL2A1 gene was performed. RESULTS: Six of the seven patients tested were high myopes with one patient being an emmetrope. Bilateral quandratic cataracts and subluxed lenses were noted in one subject. Variable but abnormal vitreous architecture was observed in all seven individuals tested. Six of the seven patients had significant hearing impairment and five of the seven patients exhibited clefting abnormalities. One patient had bilateral retinal detachments in his twenties. Six dominant disease-causing COL2A1 variants were detected. In three cases, testing of parental samples revealed that the disease-causing variant was not present in either parent. CONCLUSION: The ophthalmic features in Kniest dysplasia are very similar to those in other disorders of type II collagen such as Stickler syndrome. It is likely that different type II collagenopathies have a similar level of ocular morbidity and regular ophthalmologic examination is recommended. Kniest dysplasia is associated with heterozygous COL2A1 mutations that are frequently de novo.

SOX9 dimerization domain mutation mimicking type 2 collagen disorder phenotype.

The classification of bone dysplasia has relied on a clinical/radiographic interpretation and the identification of specific genetic alterations. The clinical presentation of the SOX9 mutation and type 2 collagen disorders overlap with the Pierre-Robin sequence and talipes equinovarus, but the former is often accompanied by the bent long bones. In its milder form, the SOX9 mutation is not necessarily associated with the bent long bones. Here, we report a patient with the Pierre-Robin sequence and talipes equinovarus who did not exhibit either bent long bones or scapular hypoplasia; thus, this patient was instead classified as having a type 2 collagen disorder. Despite this phenotypic presentation, the proposita was found to have a de novo SOX9 mutation. The peculiar location of the mutation within the dimerization domain might account for the relatively mild phenotypic effect of the SOX9 mutation to a degree that is compatible with a clinical diagnosis of type 2 collagen disorder, except for a developmental delay. We concluded that mutations in SOX9 can mimic a type 2 collagen disorder-like phenotype.

Autosomal recessive Stickler syndrome due to a loss of function mutation in the COL9A3 gene.

Stickler syndrome (STL) is a clinically variable and genetically heterogeneous syndrome characterized by ophthalmic, articular, orofacial, and auditory manifestations. STL has been described with both autosomal dominant and recessive inheritance. The dominant form is caused by mutations of COL2A1 (STL 1, OMIM 108300), COL11A1 (STL 2, OMIM 604841), and COL11A2 (STL 3, OMIM 184840) genes, while recessive forms have been associated with mutations of COL9A1 (OMIM 120210) and COL9A2 (OMIM 120260) genes. Type IX collagen is a heterotrimeric molecule formed by three genetically distinct chains: α1, α2, and α3 encoded by the COL9A1, COL9A2, and COL9A3 genes. Up to this time, only heterozygous mutations of COL9A3 gene have been reported in human and related to: (1) multiple epiphyseal dysplasia type 3, (2) susceptibility to an intervertebral disc disease, and (3) hearing loss. Here, we describe the first autosomal recessive Stickler family due to loss of function mutations (c.1176_1198del, p.Gln393Cysfs*25) of COL9A3 gene. These findings extend further the role of collagen genes family in the disease pathogenesis.

Structural basis of fibrillar collagen trimerization and related genetic disorders.

The C propeptides of fibrillar procollagens have crucial roles in tissue growth and repair by controlling both the intracellular assembly of procollagen molecules and the extracellular assembly of collagen fibrils. Mutations in C propeptides are associated with several, often lethal, genetic disorders affecting bone, cartilage, blood vessels and skin. Here we report the crystal structure of a C-propeptide domain from human procollagen III. It reveals an exquisite structural mechanism of chain recognition during intracellular trimerization of the procollagen molecule. It also gives insights into why some types of collagen consist of three identical polypeptide chains, whereas others do not. Finally, the data show striking correlations between the sites of numerous disease-related mutations in different C-propeptide domains and the degree of phenotype severity. The results have broad implications for understanding genetic disorders of connective tissues and designing new therapeutic strategies.

[Reactive perforating collagenosis]. / Collagénose perforante réactionnelle.

BACKGROUND: Reactive perforating collagenosis (RPC) belongs to the group of perforating dermatoses, which comprises elastosis perforans serpiginosa, RPC, perforating folliculitis and Kyrle's disease. RPC was initially described as a distinctive form of transepithelial elimination of altered collagen related to superficial trauma. Two types are distinguished: a hereditary type (MIM 216700), which is rare and begins during early childhood, and a second type, called acquired RPC, which is more frequent, appears in adults and is associated with other diseases, diabetes mellitus, renal insufficiency, solid tumors, lymphomas and AIDS. We report the case of a young man whose illness began during infancy, militating in favor of a diagnosis of a hereditary form of RPC. The description of similar lesions in the patient's brother confirmed our diagnosis. PATIENTS AND METHODS: A 26-year-old man, the child of consanguinous parents, presented crusted papular lesions on his hands. The cutaneous lesions, located on the external side of the limbs, had been present since childhood, with flares during winter. Histologic analysis showed a cup-shaped depression in the epidermis containing keratinous material with extruded degenerated collagen towards the cutaneous surface. Treatment with topic retinoids did not result in any real resolution of the disease. The patient reported the presence of similar lesions in his brother, which was consistent with our diagnosis. DISCUSSION: The pathogenesis of hereditary RPC is still unknown, even if superficial trauma is suspected as the cause of RPC. In contrast, in diabetes, acquired RPC pathogenesis has recently been related to advanced glycation end-products of collagen.

Clinical phenotypes associated with type II collagen mutations.

COL2A1 mutations give rise to a spectrum of phenotypes predominantly affecting cartilage and bone from the severe disorders that are perinatally lethal to the milder conditions that are recognised in the post-natal period and childhood. The milder chondrodysplasias are characterised by disproportionate short stature, eye abnormalities, cleft palate and hearing loss. It remains poorly recognised that there is significant variability in the disease presentation, with early onset short stature conditions and later onset milder phenotypes. Similarly, it is under-acknowledged that COL2A1 mutations may solely cause joint disease in the absence of the other mentioned phenotypic clues. The underlying hypothesis is that there are novel phenotypes caused by mutations in type II collagen that extend from premature arthritis through to more severe bone dysplasias. The importance of finding a COL2A1 mutation lies in the subsequent ability to accurately assess recurrence risks and offer information regarding disease natural history. Most importantly, it enables at-risk individuals to be identified for implementation of preventative strategies and early ameliorative management of their condition. Such interventions potentially translate into a reduction in health costs associated with musculoskeletal disease.

Novel FH mutation in a patient with cutaneous leiomyomatosis associated with cutis verticis gyrata, eruptive collagenoma and Charcot-Marie-Tooth disease.

Multiple cutaneous and uterine leiomyomatosis (MCUL)/hereditary leiomyomatosis and renal cell cancer (HLRCC) (OMIM 150800/OMIM 605839) is a rare hereditary disorder leading to the development of benign cutaneous and uterine smooth muscle tumours in young adults.(1,2) This disease is characterized by an increased risk of developing renal cell carcinomas.(3) It results from dominantly inherited autosomal mutations in the fumarate hydratase (FH) gene.(4) This gene encodes a Krebs cycle enzyme, present in both cytosolic and mitochondrial compartments, and probably acts as a tumour suppressor gene. We report a 22-year-old man affected by cutaneous leiomyomatosis associated with cutis verticis gyrata, disseminated collagenoma and Charcot-Marie-Tooth disease, who was harbouring the novel FH gene mutation c.821C > T, p.Ala274Val.

Upregulation of stromal cell derived factor-1alpha in collagen vascular diseases-associated interstitial pneumonias (CVDs-IPs).

OBJECTIVE: We speculated that distinct angiogenic profiles are involved in idiopathic interstitial pneumonias (IIPs) in comparison with interstitial pneumonias associated with collagen vascular disease (CVD-IPs). This hypothesis was investigated by measuring the expression of a cardinal biologic axis, the vascular endothelial growth factor (VEGF)-stromal derived growth factor [SDF-1alpha, transcripts 1 and 2 (TR1 and TR2)] and receptor, CXCR4 and the angiogenetic receptors CXCR2 and CXCR3 in bronchoalveolar lavage fluid (BALF) in both conditions. METHODS: We studied prospectively 25 patients with fibrotic IIPs (f-IIPs) [20 with idiopathic pulmonary fibrosis (IPF) and 5 with idiopathic non-specific interstitial pneumonia (NSIP)] and 16 patients with CVD-IPs. mRNA expression was measured by Real-Time RT-PCR and protein was evaluated by Western Blotting. RESULTS: A significantly greater value has been detected in SDF-1alpha-TR1 mRNA expression levels of CVD-IPs (p=0.05) in comparison with IPF group. A similar trend has been also detected in protein expression in favor of CVD-IP group. In addition, VEGF mRNA levels have been found significantly increased in CVD-IPs in comparison with the NSIP group (p=0.05). No significant difference has been found in SDF-1alpha-TR2-CXCR4 mRNA and CXCR2-CXCR3 between the two groups. CONCLUSION: These results showed increased expression of SDF-1alpha in CVD-IPs, suggesting different angiogenic procedures. Further studies are needed in order to better explore the angiogenetic pathway in these disorders.

Genetic and orthopedic aspects of collagen disorders.

PURPOSE OF REVIEW: 'Collagens' are a family of structurally related proteins that play a wide variety of roles in the extracellular matrix. To date, there are at least 29 known types of collagen. Accordingly, abnormality in the various collagens produces a large category of diseases with heterogeneous symptoms. This review presents genetic and orthopedic aspects of type II, IX, and XI collagen disorders. RECENT FINDINGS: Although a diverse group of conditions, mutation of collagens affecting the articular cartilage typically produces an epiphyseal skeletal dysplasia phenotype. Often, the ocular or auditory systems or both are also involved. Treatment of these collagenopathies is symptomatic and individualized. Study of tissue from animal models allows examination of mutation effects on the abnormal protein structure and function. SUMMARY: The collagen superfamily comprises an important structural protein in mammalian connective tissue. Mutation of collagens produces a wide variety of genetic disorders, and those mutations affecting types II, IX, and XI collagens produce an overlapping spectrum of skeletal dysplasias. Findings range from lethal to mild, depending on the mutation of the collagen gene and its subsequent effect on the structure and/or metabolism of the resultant procollagen and/or collagen protein and its function in the body.

Autosomal recessive myosclerosis myopathy is a collagen VI disorder.

OBJECTIVE: To determine the clinical and molecular features of a new phenotype related to collagen VI myopathies. METHODS: We examined two patients belonging to a consanguineous family affected by myosclerosis myopathy, screened for mutations of collagen VI genes, and performed a detailed biochemical and morphologic analysis of the muscle biopsy and cultured fibroblasts. RESULTS: The patients had a novel homozygous nonsense COL6A2 mutation (Q819X); the mutated messenger RNA escaped nonsense-mediated decay and was translated into a truncated alpha2(VI) chain, lacking the sole C2 domain. The truncated chain associated with the other two chains, giving rise to secreted collagen VI. Monomers containing the truncated chain were assembled into dimers, but tetramers were almost absent; secreted collagen VI was quantitatively reduced and structurally abnormal in cultured fibroblasts. Mutated collagen did not correctly localize in the basement membrane of muscle fibers and was absent in the capillary wall. Ultrastructural analysis of muscle showed an unusual combination of basement membrane thickening and duplication, and increased number of pericytes. CONCLUSIONS: This familial case has the characteristic features of myosclerosis myopathy and carries a homozygous COL6A2 mutation responsible for a peculiar pattern of collagen VI defects. Our study demonstrates that myosclerosis myopathy should be considered a collagen VI disorder allelic to Ullrich congenital muscular dystrophy and Bethlem myopathy.