MN blood groups and bipolar disorder: evidence of genotypic association and Hardy-Weinberg disequilibrium.
BACKGROUND
MN blood groups have been studied in the past as a genetic marker of biopolar disorder (BD). Several previous studies reported an association of the illness with lower frequency of blood group NN.


METHODS
We analyzed distribution of MN blood groups in a sample of 174 patients with BD, 176 with unipolar depression, 98 with schizophrenia, and 331 healthy controls. In addition, we tested whether the inferred genotypes. conform to Hardy-Weinberg equilibrium (HWE).


RESULTS
The frequency of NN phenotype was significantly lower among the bipolar patients than in any of the other three groups (p < .001). The genotype frequencies in the BD group deviated significantly from those expected under HWE (p < .01).


CONCLUSIONS
These results suggest a possible locus on chromosome 4 (4q28-q31.1) associated with genetic susceptibility to bipolar illness.
Department of Psychiatry, University of Ottawa, Ontario, Canada.
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D000483:Alleles; D001714:Bipolar Disorder / Q000097:blood / Q000235:genetics*; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D008951:MNSs Blood-Group System / Q000235:genetics*; D012559:Schizophrenia / Q000097:blood / Q000235:genetics
D008951:MNSs Blood-Group System