General News Research — 07 March 2013
Five psychiatric disorders genetically linked

Five major psychiatric disorders may share some genomic risks, according to the largest genetic study of mental illnesses to date.

The findings mark early but important progress towards psychiatric diagnosis that is not dependent on a patient’s symptoms the study authors suggest, but an Australian expert offers a more conservative appraisal of the results.

The research published today in the Lancet suggests the five disorders genetically mapped by the Psychiatric Genomic Consortium – autism, ADHD, bipolar disorder, major depressive disorder and schizophrenia – have some genetic overlap.

After analysing the genome-wide single-nucleotide polymorphism (SNP) data of the five disorders among more than 33,000 cases and close to 28,000 controls of European descent, the consortium found several specific SNPs that were associated with all five disorders.

Of particular interest were variations in calcium-channel activity genes which, “could represent a fundamental mechanism contributing to a broad vulnerability to psychopathology”, the authors reported.

The findings build on previous research suggesting some genetic risk factors are shared across neuropsychiatric disorders, most notably the genetic links between schizophrenia and bipolar disorder.

“The identification of genetic variants that confer risk of a diverse set of psychiatric disorders parallels findings from other medical specialties,” the researchers wrote.

Though this kind of research was the “logical next step … to my mind [the researchers] have been more upbeat than the data really supports,” said Professor David Castle, Chair of Psychiatry at the University of Melbourne.

“It’s a credit to them that they have pooled these samples … but you have to ask: what does it show that we didn’t already know? There’s an awful lot ofoverlap and an awful lot of homogeneity [between the disorders],” he told  Psychiatry Update.

“And talk about how this can inform etiologically-driven nosology, I think if anything this is a setback for that.

This is saying their current constructs are not etiologically homogeneous and it also reconfirms that a lot of factors underpinning all mental illnesses are common and can be said for environmental factors too,” he said.

Contrary to comments made in a Lancet editorial, “I don’t see what it says about therapeutic implications or biomarkers or anything like that,” said Professor Castle.

“I don’t think [genomics wide association studies] is going to get us any further, I’m afraid,” he added.

As first appeared in Psychiatry Update, 6th March 2013

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