MASA syndrome (mental retardation, aphasia, shuffling gait and adducted thumbs) is an X-linked disorder first described in 1974. Since that time, two further pedigrees have been reported with similar features. The main clinical features are summarised by the acronym. Kenwrick et al. reported a separate family with X-linked recessive spastic paraplegia and mental retardation and demonstrated close linkage to DXS15 and DXS52 (DX13 and St14) at Xq28. Four affected individuals in this family were said to have absence of the extensor pollicis longus. Here we report a family where two adult brothers and their nephew have the phenotype of MASA syndrome. We demonstrate by clinical and gene mapping studies that MASA syndrome is most likely the same condition as that described by Kenwrick et al., and we review its clinical course and presentation.