Neurological soft-signs and minor physical anomalies in schizophrenia: differential transmission within families.

Markers of vulnerability have been identified in schizophrenia, and among them, neurological soft-signs (NSS) and minor physical anomalies (MPAs) also seem to occur in biological relatives. The similarities of these developmental markers within families may depend on either genetic or non-genetic factors. The aim of the study was to investigate the intra-familial similarities of NSS and MPAs within 18 nuclear families (18 probands with schizophrenia and 36 of their non-psychotic parents). A general linear model showed similarities within families for NSS (intra-class coefficient [ICC] = 0.64; F = 2.6; df = 17.17; p = 0.02) but not for MPAs (ICC = -0.10; F = 0.7; df = 17.17; ns). We thus found a direct evidence for the intra-familial transmission of NSS but not of MPAs, suggesting that this morphological phenotypic trait could be more dependent on epigenetic influences.