Gustavson syndrome: A disorder first reported in 1999 by Gustavson and colleagues as a new X-linked mental retardation syndrome. In the family they studied there were 7 male children in 2 generations with the syndrome. The affected males were genealogically connected through females who were presumed to be carriers of the gene responsible for the syndrome.
In addition to severe mental retardation, the syndrome includes microcephaly, optic atrophy with severely impaired vision or blindness, severe hearing defect, spasticity, epileptic seizures, restricted movement of the large joints, and death in infancy or early childhood.
GUST, the gene that causes Gustavson syndrome, has been shown (through linkage analysis) to be on the X chromosome and to be, specifically, in chromosome band Xq26. At least two other mental retardation syndromes (Borjeson and Pettigrew syndromes) have been mapped to the same region.