An autosomal recessive syndrome of severe mental retardation, cataract, coloboma and kyphosis maps to the pericentromeric region of chromosome 4.

We report on three siblings with a novel mental retardation (MR) syndrome who were born to distantly related Iranian parents. The clinical problems comprised severe MR, cataracts with onset in late adolescence, kyphosis, contractures of large joints, bulbous nose with broad nasal bridge, and thick lips. Two patients also had uni- or bilateral iris coloboma. Linkage analysis revealed a single 10.4 Mb interval of homozygosity with significant LOD score in the pericentromeric region of chromosome 4 flanked by SNPs rs728293 (4p12) and rs1105434 (4q12). This interval contains more than 40 genes, none of which has been implicated in MR so far. The identification of the causative gene defect for this syndrome will provide new insights into the development of the brain and the eye.