PATERNAL TRANSMISSION AND ANTICIPATION IN SCHIZOPHRENIA

Recent studies have observed anticipation (earlier age at onset (AAO) or increased disease severity in successive generations) in familial s chizophrenia. In other disorders, where the molecular mechanism (repea t expansion) is known, anticipation varies in degree depending on the sex of the transmitting parent. We investigated parental sex effects o n anticipation in schizophrenia, using a familial sample of affected t wo-generation pairs in which anticipation had previously been demonstr ated using the median intergenerational difference (MID) in AAO. A Wil coxon rank sum test for independent samples was used to determine whet her MID in AAO was significantly different for paternal and maternal t ransmission. Results suggested that in a sample of 127 parent-offsprin g pairs, anticipation was greater with paternal than with maternal tra nsmission (MID = 18 and 14 years, respectively, P = 0.05). Paternal ef fects were strongest in 39 parent-offspring pairs with early-onset off spring (less than or equal to 21 years) (MID = 22 and 17 years, respec tively, for paternal and maternal transmission, P = 0.01). However, as sessment of the effect of possible selection biases suggests that pref erential ascertainment of late-onset fathers may have exerted importan t effects. While the results support possible paternal effects, furthe r studies are needed to draw firm conclusions about true parent-of-ori gin effects on anticipation in familial schizophrenia. (C) 1998 Wiley- Liss, Inc.