[Familial forms of schizophrenia. Cytogenetic study].

As a preliminary step in the search for chromosomal location of a susceptibility gene predisposing to schizophrenia, cytogenetic screening of patients might be useful. Search for chromosomal aberrations has successfully directed and accelerated the identification of several disease genes, such as the Duchenne muscular dystrophy gene, retinoblastoma, Burkitt's lymphoma and chronic myeloïd leukemia. Although karyotypes abnormalities do not account for a large portion of cases of Schizophrenia, the two candidate regions predisposing to this disease resulted from observation of chromosomal abnormalities. First, the identification of a partial trisomy of the 5q11-q13 region (Basset et al., 1988) led Sherrington et al. (1988) to report a positive linkage with markers localized on the long arm of chromosome 5, which has not yet been replicated (Kauffman et al., 1989; Kennedy et al., 1988; St Clair et al., 1989). Second, on the basis of frequent cytogenetic abnormalities of the sex chromosome (DeLisi, 1985) in addition to epidemiological observations, Crow (1988) suggested that there could be a locus for psychosis within the pseudoautosomal region, a data which has been recently confirmed (Collinge et al., 1991). With the hypothesis that such aberrations could be more frequent among schizophrenics who have at least one affected first-degree relative, we undertook cytogenetic screening on a sample recruited from consecutive psychiatric admissions to a Psychiatric facility (Hôpital Saint Paul) involving patients living in a limited geographical area on the island of La Réunion, a French Department in the Indian Ocean.(ABSTRACT TRUNCATED AT 250 WORDS)