Anticipation and imprinting in Spanish families with schizophrenia.

Evidence of imprinting and anticipation, two genetic phenomena that are correlated with clinical sequelae, was assessed in familial schizophrenia. A sample of patients (n=291) who fulfilled the ICD-9 criteria for schizophrenia and corresponding to the familial-type and sporadic-type of the disorder was recruited. Clinical anticipation and imprinting variables such as age at onset (AAO), schizophrenia subtype, course of disease and onset type were assessed over parental (G1) and filial (G2) generations in both schizophrenia types. Anticipation assessment indicated significant differences in mean AAO between parent-offspring pairs in unilineal families. These differences were not explained by a cohort effect. Imprinting assessment indicated non-significant differences in AAO between the offspring of affected mothers and the offspring of affected fathers. The results obtained for other clinical variables were non-conclusive. The results suggest that anticipation, but not imprinting, is operative in schizophrenia.