Here we report on 2 mentally retarded sisters with clinical signs and symptoms not seen in a previously delineated MCA/MR syndrome, i.e., normal pre- and perinatal history, severe mental retardation with severe delay in psychomotor development and without development of primary motor abilities and speech, characteristic face with maxillary hypoplasia, large mouth with down-turned corners, short philtrum and everted lower lip, associated with a remarkable ectomorphic habitus.