Diastrophic dysplasia and atelosteogenesis type II as expression of compound heterozygosis: first report of a Mexican patient and genotype-phenotype correlation.

The osteochondrodysplasias represent a heterogeneous group of cartilage and bone diseases. Among these, achondrogenesis 1B, atelosteogenesis type II, diastrophic dysplasia, and autosomal recessive multiple epiphyseal dysplasia are caused by mutations in the solute carrier family 26 (sulfate transporter), member 2 gene (SLC26A2). This group of osteochondrodysplasias shows a continuous spectrum of clinical variability and shares many features in common. Usually, it is difficult to distinguish clinically among these patients. To date, several efforts have been made to correlate mutations in the SLC26A2 gene with phenotypic severity in the patients. We report on a Mexican girl with diastrophic dysplasia presenting some unusual clinical and radiographic features that are usually observed in atelosteogenesis type II. Molecular analysis of the SLC26A2 gene in this patient showed compound heterozygosity for the R178X and R279W mutations. In this patient, the combination of a mild and a severe mutation has apparently led to an intermediate or transitional clinical picture, showing an apparent genotype-phenotype correlation.