X-linked intellectual disability, Cabezas type is characterised by intellectual deficit, muscle wasting, short stature, a prominent lower lip, small testes, kyphosis and joint hyperextensibility. An abnormal gait, tremor, decreased fine motor coordination and impaired speech are also present. The syndrome has been described in six boys from three generations of the same family. Transmission is X-linked and the causative gene has been localised to the q24-q25 region of the X chromosome.