Achondrogenesis, type IB (ACG1B; MIM 600972) is a lethal condition caused by the diastrophic dysplasia sulfate transporter gene mutations (DTDST/SLC26A2). Affected fetuses are usually in breech position and appear hydropic. The limbs and the trunk are shortened. In contrast to the findings in achondrogenesis, type II (ACG2; MIM 200610), the head is of a normal or near normal size and the fingers and toes are short. The feet and toes are rotated inward, a finding shared with diastrophic dysplasia (DTD; MIM 222600), another disorder caused by DTDST mutations.