No Evidence for Linkage and Linkage Dysequilibrium of Schizophrenia to Notch4 Locus in Taiwanese Families

Evidence was reported for a highly significant linkage disequilibrium between schizophrenia and a trinucleotide repeat polymorphism (CTG)n in exon 1 of NOTCH4 gene located at chromosome 6p21 [Wei and Hemmings, 2000]. In order to evaluate linkage disequilibrium of schizophrenia to this locus, we genotyped this polymorphism in 103 Taiwanese schizophrenic families with at least two affected siblings. Linkage disequilibrium was assessed using the Family Based Association Test Program (FBAT). The result didn’t support the association of this polymorphism with schizophrenia as previously reported (chi-square¼3.782, P¼0. 436 ).We also genotyped two flanking microsatellite markers and evaluated linkage of schizophrenia to this chromosome region using GENEHUNTER program. Non-parametric analysis revealed slightly positive NPL scores over this region (NPLZ¼0 .91, P¼0.17). Our results didn’t support linkage or linkage disequilibrium evidence of schizophrenia to the NOCTH4 locus in an ethnically distinct Taiwanese sample.