Anticipation in Japanese families with schizophrenia

The identification of anticipation in schizophrenia is a recent focus in th e genetic epidemiology of schizophrenia, although it involves some controve rsial methodological issues. We explored the evidence of anticipation among 44 Japanese two-generation pairs with schizophrenia found by reviewing nin e years of admission records (1986-1994) at the Department of Neuropsychiat ry, Nagasaki University Hospital and Michino-o Hospital, Nagasaki. The 44 p airs consisted of 27 two-generation pairs of first-degree relatives group ( FDRG) and 17 pairs of second-degree relatives group (SDRG). On pairwise com parison and a life table analysis, the age at onset (AO) was significantly earlier in the lower generation (G2) than in the upper generation (G1) in a ll of the pairs and in the two subgroups, FDRG and SDRG. Earlier AO was sho wn in G2 even after minimizing some statistical biases for the study of ant icipation in schizophrenia. A significant earlier mean AO was found in G2 e ven when a cohort effect was controlled for. There was no marked difference in AO between paternal and maternal transmission. These results provide fu rther evidence for epidemiological anticipation, suggesting biological anti cipation such as the involvement of trinucleotide repeats expansion in G2. The limitations of the study are also discussed.