Study finds gene linked to response to lithium

PINPOINTING::Despite being widely prescribed to treat mood disorders for 50 years, no clinical predictors had been found to decide who would respond well to lithium

By Lee I-chia  /  Staff reporter

Thu, Jan 16, 2014 - Page 3

A group of Taiwanese scientists and psychiatrists has identified a gene associated with response to lithium maintenance treatment for bipolar I disorder in ethnic Han Chinese patients, the Academia Sinica said yesterday.

Bipolar I is a mood disorder characterized by recurrent episodes of mania, with some patients experiencing episodes of severe depression, it said.

While lithium has been prescribed to patients as an effective treatment for bipolar disorder for nearly 50 years, no clinical predictors or genetic markers had been found to accurately identify bipolar patients who respond well to lithium prophylaxis clinical treatment.

The group of scientists from Academia Sinica and the Institute of Biomedical Sciences, along with psychiatrists from 44 hospitals, discovered that three generic variants in the gene encoding glutamate decarboxylase-like protein 1 (GADL1) can be used as biomarkers to predict the response to lithium maintenance treatment in ethnic Han Chinese patients with bipolar I disorder.

A chart showing 1,761 patients’ clinical course and drug treatment history — including the use of mood stabilizers and psychotropics — was constructed by the research group, combined with information gathered from interviews with the patients, their family members and psychiatrists, and followed by a comprehensive medical-chart review.

A genomewide association study on samples from one subgroup of 294 patients with bipolar I disorder who were receiving lithium treatment for at least two years tested the single-nucleotide polymorphisms (SNP) that showed the strongest association with a response to lithium for association in a replication sample of 100 patients.

It then tested them in a follow-up sample of 24 patients

The group found that nearly half of the 1,761 patients (47.2 percent ) with bipolar I disorder in the study carry the response allele T in a variant of GADL1, suggesting that half of the patients with bipolar I disorder in Taiwan may benefit from effective lithium treatment.

The research results was published in The New England Journal of Medicine on Thursday last week.