Researchers conducted a genome-wide association study (GWAS) that enrolled 1,209 Turkish people affected by Behcet's disease and 1,278 unaffected Turkish peopleall residents of the country. They looked at many points on the human genome called single-nucleotide polymorphisms (SNPs), with each SNP representing a difference in a single DNA building block, called a nucleotide. Researchers then compared SNP differences between people with and without disease.
From nearly 800,000 SNPs, researchers detected and mapped a small number that are found in those who have Behcet's disease at a significantly higher rate than in those without the disease, suggesting that the variant or another one nearby contributes to the disease.
"Each of the genetic factors may contribute a little to the overall risk of disease," said Elaine F. Remmers, Ph.D., staff scientist in NHGRI's Inflammatory Disease Section and study co-author. "We are also identifying them in pathways that are important in inflammatory disease development."
She noted that not all of the 800,000 gene variants analyzed were directly genotyped. Genotyping involves examining a person's DNA at a site where a variation is commonly known to occur. Instead, the team used the strategy of imputing, or surmising, that there were genotypes worth investigating near known variants.
"That worked very well for us," Dr. Remmers said. "We found that our predicted genotypes were pretty good and that the associations we found were quite similar in both the predicted and the experimentally confirmed genotypes."
Each of the four newly identified gene regions is already known to play a role in immune regulation. The genetic associations have helped classify Behcet's disease with more commo
|Contact: Raymond MacDougall|
NIH/National Human Genome Research Institute