Recently, the media has mourned the 5HTT-LPR which was stripped of its celebrity risk-allele status. Another gene however, the BDNF val66met variant (just a B-list celeb at the moment) has been slowly acquiring similar interest as the genetic variant that can be counted on to confer a biological association with any number of brain-based phenotypes, behaviors and – dare I say – grant funding.
Not so fast – according to Verhagen et al., in their recent, “Meta-analysis of the BDNF Val66Met polymorphism in major depressive disorder: effects of gender and ethnicity” [doi: 10.1038/mp.2008.109]. Here they report on 2,812 cases and 10,843 controls from 12 research studies on major depression. Their analysis found no overall association of the Met allele with major depression. However, when they consider just men who carry the Met/Met genotype, there was a significant association with risk of MDD.
Perhaps amidst the clamor as BDNF rises to the celebrity darling du jour, we can think more on the futility of the “disorder x genotype” approach in general and more on how best to make sense of – and productive use of – our genetic information. Genetic associations (spurious as they are) with DSM-IV clinical descriptions may not be particularly meaningful. Somehow, the basic biology and the clinical descriptions of what we call mental illness do not seem to be linking-up very well. Perhaps more celebrity-genes will have to fall from grace before we come to a new conceptual paradigm.