The clinical features of Ehlers-Danlos syndrome type VII due to a deletion of 24 amino acids from the pro alpha 1(I) chain of type I procollagen

W G Cole, R Evans, D O Sillence
1987 Journal of Medical Genetics  
The clinical features and progress of a child with the type VII form of Ehlers-Danlos syndrome due to a deletion in the procti(I) of type I procollagen were studied. The child was born with bilateral dislocations of hips and knees and all other joints were markedly hypermobile. Persistent severe joint instability was the major clinical abnormality. She had a depressed nasal bridge with prominent paranasal folds and deeply set eyes with mild hypertelorism and micrognathia. The skin was soft,
more » ... rately hyperelastic, and sagged over the face and knees. Skin fragility and easy bruising appeared when she started walking. Electron microscopy of the dermis showed irregular collagen fibrils. Ehlers-Danlos syndrome (EDS) is a heterogeneous genetic disorder of the connective tissues. ' The major phenotypic features include joint hypermobility and skin changes such as thinness, hyperextensibility, and fragility. In humans, the type VII form of this syndrome (EDS VII) is characterised by severe joint laxity with multiple dislocations and subluxations.2 This form of EDS has been shown to involve impaired removal of the amino terminal Npropeptides from procollagen.>4 In the EDS VIIA variant, the N-propeptides are incompletely removed because of reduced activity of procollagen N-proteinase.2 Partially processed proal(I) and proa2(I) chains of type I procollagen are found in the tissues of such patients. These biochemical findings also exist in dermatosparaxis ('torn skin'), a recessively inherited disease of cattle, sheep, and cats. ' The biochemical defects in the EDS VIIB variant involve structural alterations of the proaul(I) or proa2(I) chains, which prevent cleavage of the abnormal chain by procollagen N-proteinase.' A peptide deletion, including the N-proteinase cleavage site, has been reported in the proa2(I) chain of a
doi:10.1136/jmg.24.11.698 fatcat:lww6wrf5xfcrzhk4u547i2lkc4