FAMILIAL SPONDYLOEPIPHYSEAL DYSPLASIA TARDA, BRACHYDACTYLY, AND PRECOCIOUS OSTEOARTHRITIS ASSOCIATED WITH AN ARGININE-75-]CYSTEINE MUTATIONIN THE PROCOLLAGEN TYPE-II GENE IN A KINDRED OF CHILOE ISLANDERS .1. CLINICAL, RADIOGRAPHIC, AND PATHOLOGICAL FINDINGS

Objective. To characterize a kindred of Chiloe Islanders with spondylo epiphyseal dysplasia tarda (SEDT), brachydactyly, precocious osteoarth ritis (OA), and intraarticular calcification. Methods. Sixteen family members underwent a complete physical examination, anthropometric meas urements, radiographic studies of the spine and peripheral joints, and analysis of the type II procollagen gene (COL2A1). Results. Seven fam ily members presented with SEDT, brachydactyly, precocious OA, and per iarticular calcification while 2 others had the same syndrome but with out brachydactyly. The inheritance was autosomal dominant, and the dis ease cosegregated with a base substitution in the COL2A1 gene. Conclus ion. The syndrome of SEDT, precocious OA, and brachydactyly in a kindr ed of Chiloe Islanders is associated with a point mutation in 1 allele of the COL2A1 gene. The relationship of this type of SEDT to familial calcium pyrophosphate dihydrate deposition disease and idiopathic hip dysplasia, both endemic in Chiloe Islanders, needs to be further inve stigated.