Association between hSKCa3 and schizophrenia not confirmed by transmission disequilibrium test in 193 offspring/parents trios

A possible association between the small conductance calcium-regulated potassium channel gene, hSKCa3, and schizophrenia has recently been described by Chandy et al1 using a case-control design with patients with schizophrenia (n = 141) and matched controls (n = 158). The gene may be considered as an excellent candidate gene for psychiatric disorders, since it plays a role in modulating neuronal firing patterns by regulating the slow component of afterhyperpolarisation. In addition, the gene contains a highly polymorphic trinucleotide sequence (CAG) within exon 1, which encodes a polyglutamine stretch. The possible contribution of unstable trinucleotide repeats to the development of psychiatric disorders has previously been discussed.2–4 Chandy et al1 reported an over-representation of alleles with higher repeat number in schizophrenics as compared to controls (P = 0.0035). In an attempt to replicate these findings, we have performed a family-based study with 193 offspring/parent combinations using a sample of 49 multiplex families (two or more affected siblings with parents) and a second sample of 83 simplex families (one affected offspring with parents). No evidence for the association of longer repeats with schizophrenia was obtained when each sample was tested separately or when both samples were combined and tested for transmission disequilibrium.