“…Mutations in the adenylosuccinate lyase gene on chromosome 22q13.1-q13.2 have been reported in three sibs with autism [Stone et al, 1992], but not in a follow-up study of 119 patients with autism [Fon et al, 1993]. Finally, the appearance of autism in a small number of patients with various other genetic disorders (Fragile X syndrome, Rett syndrome, Goldberg-Shprintzen syndrome, Asperger syndrome, Brachmann-deLange syndrome, hypomelanosis of Ito, Joubert syndrome, neurofibromatosis, phenylketonuria, and tuberous sclerosis) is consistent with a genetic cause for autism and the potential involvement of a large number of genes in the development of language and social skills [Akefeldt and Gillberg, 1991;Annerén et al, 1995;Bay et al, 1993;Brown et al, 1986;Cohen et al, 1991;Folstein and Piven, 1991;Gillberg and Coleman, 1996;Holroyd et al, 1991;Hunt and Shepherd, 1993;Li et al, 1993;McKusick, 1994;Yomo et al, 1991]. This contention is further supported by sporadic reports describing a number of chromosome abnormalities, each of which has been seen in only one or a small number of patients with autism (Table I).…”