Public release date: 25-Mar-2012 [ | E-mail | Share ]

Contact: Marjorie Montemayor-Quellenberg mmontemayor-quellenberg@partners.org 617-534-2208 Brigham and Women's Hospital

BOSTON, MAHuman geneticists have long debated whether the genetic risk of the most common medical conditions derive from many rare mutations, each conferring a high degree of risk in different people, or common differences throughout the genome that modestly influence risk.

A new study by Brigham and Women's Hospital (BWH) researchers has harnessed data and new analysis tools to address this question in four common diseases: rheumatoid arthritis; celiac disease; coronary artery disease and myocardial infarction (heart attack); and type 2 diabetes.

The study will be electronically published on March 25, 2012 in Nature Genetics.

The researchers developed a new statistical method built upon "polygenic risk score analysis" to estimate the heritable component of these diseases that is explained by common differences throughout the genome.

Their method takes advantage of data from previously published genome-wide association studies, or GWAS, an approach used to scan DNA samples for common genetic markers seen throughout the populationcalled SNPs (single nucleotide polymorphisms).

According to senior author Robert Plenge, MD, PhD, BWH director of Genetics and Genomics in the Division of Rheumatology, Immunology and Allergy, "We used GWAS data and a Bayesian statistical framework to demonstrate that a substantial amount of risk to these four common diseases is due to hundreds of loci that harbor common causal variants with small effect, as well as a smaller number of loci that harbor rare causal variants."

Using data on rheumatoid arthritis, they estimated that variation in hundreds of locations throughout the genome might explain 20 percent of rheumatoid arthritis risk, after excluding all of the known rheumatoid arthritis genetic risk factors.

They used computer simulations to demonstrate that the underlying genetic risk in rheumatoid arthritis is largely explained by many common alleles rather than rare mutations.

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A hidden architecture: Researchers use novel methods to uncover gene mutations for common diseases