MedWire News: Variants in the ankyrin-3 gene (ANK3) play a role in bipolar disorder development, but there is no evidence for a link with schizophrenia, conclude European scientists.
Recently, two single nucleotide polymorphisms (SNPs) in ANK3 were identified as independent risk factors for bipolar disorder, while another has been linked to schizophrenia.
To investigate further, Micha Gawlik, from the University of Würzburg in Germany, and colleagues genotyped 920 schizophrenia patients, 400 bipolar affective disorder patients, 220 unipolar depression patients, and 480 healthy controls for the ANK3 SNPs rs9804190, and rs10994336, which have been linked to bipolar disorder, and rs10761482, which has been associated with schizophrenia.
The patients were further classified using Leonhard's system into 228 with systematic schizophrenia, 635 with unsystematic schizophrenia, 309 with cycloid psychosis, 284 with manic depression, and 90 with monopolar depression.
For SNPs rs9804190 and rs10994336, no association with schizophrenia, bipolar affective disorder, or unipolar depression was identified. While the risk allele of SNP rs10761482 was significantly associated with bipolar affective disorder, at an odds ratio of 1.3, no such associations were revealed with either schizophrenia or unipolar depression.
The team also reports in the journal BMC Psychiatry that classification using Leonhard's system yielded no significant associations across any of the subgroups, and neither did analyzing the patients by haplotype.
They write: "In conclusion, our results support a genetic contribution of ANK3 to ICD [International Classification of Diseases] 10 bipolar disorder, though we failed to replicate findings for schizophrenia according to ICD 10 or Leonhard's classification.
"Our study cannot confirm ANK3 as a common risk factor for both diseases, challenging the hypothesis that bipolar disorder and schizophrenia are just different phenotypes of the same disease."
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