X-linked mental retardation Miles-Carpenter type has characteristics of severe intellectual deficit, microcephaly, exotropia and low digital arches. It has been described in four male members of one family. Joint hypermobility, distal muscle wasting, hypogonadism and rocker bottom feet were also reported. Low digital arches and exotropia were described in several female members of the family. Transmission is X-linked and the causative gene has been mapped to Xq13-q22.