Genetic locus for migraine–bipolar comorbidity uncovered
MedWire News: Comorbid migraine and bipolar disorder (BD) appears to be underpinned by a genetic susceptibility locus on chromosome 4 and possibly another on chromosome 20, conclude US researchers.
While clinically heterogeneous, BD and migraine have a significant genetic component. Previous studies have identified overlapping regions of genetic linkage and two functional similar voltage-dependent calcium channels have been associated with both disorders.
To investigate further, Ketil Joachim Oedegaard, from the University of California, San Diego, and colleagues studied data from the National Institutes of Health Genetics Initiative for Bipolar Disorder. They identified 31 families with both migraine and bipolar disorder, yielding a total of 201 individuals, including 105 siblings with either broad or narrow phenotypes for both disorders.
The results, published in the Journal of Affective Disorders, indicate that there was a linkage signal at chromosome 4q24 for migraine, although not BD, at a logarithm of odds (LOD) score of 2.26, which the team notes has been significantly linked to migraine in two previous samples.
Furthermore, a locus on chromosome 20p11 was found to have overlapping association with both migraine and BD, at LOD scores of 1.95 and 1.67, respectively. Again, this region has been previously linked to BD and contains the potassium dependent sodium/calcium exchanger gene SLC24A3.
The team concludes: “The findings here suggest that information regarding a prevalent comorbid neurological disorder (ie, migraine) can provide an additional tool for stratifying a bipolar study sample.”
They add: “It is hoped that this approach will facilitate the detection of underlying mutation(s) elucidating the complex relation between migraine and BD, and that this approach will help unravel molecular pathways and the development of rational treatment strategies for both disorders.”
MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2009
By Liam Davenport