First genetic links to major depression identified

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The CONVERGE consortium identified two genetic associations by focusing on a sample of Chinese women with recurrent severe depression…[Now that] the first genetic associations with depression have been identified, this number is expected to increase linearly with sample size….

Depression is a complex disorder with a heritability of 37% estimated from twin studies. Despite robust evidence for a genetic component, identifying the specific genetic variants involved in the disorder has been a major challenge.

There are several reasons why identifying risk loci for major depressive disorder (MDD) has proven difficult. First, like most complex diseases, depression is a polygenic disorder arising from the combined effect of many genetic variants with individually small effect sizes…[In addition,] the heritability of MDD is modest, at 37%, compared with other psychiatric disorders, meaning that risk alleles are likely to have smaller effect sizes[, requiring larger sample sizes].

The studies described here illustrate two approaches to dissect the genetic contribution to depression: through a case-control study of lifetime diagnosis of depression or using a continuous measure of the count of depressive symptoms…As the results of CONVERGE and the 23andMe studies show, both approaches can be successful in identifying genetic variants for depression.

The GLP aggregated and excerpted this blog/article to reflect the diversity of news, opinion, and analysis. Read full, original post: Genetics of Depression: Progress at Last