Scientists from Queen Mary, University of London, said the sequencing is important because a complex combination of genetic and environmental factors are thought to cause the diseases studied -- autoimmune thyroid disease, celiac disease, Crohn's disease, psoriasis, multiple sclerosis and type 1 diabetes.
In the study, a global team of scientists led by the British university sought to identify new variants in 25 previously identified risk genes associated with the diseases.
Some scientists had suggested a small number of rare variants in risk genes are likely to be a major cause of the heritability of the conditions, but the new study, published in the journal Nature, suggests the genetic risk of the diseases more likely involves a complex combination of hundreds of common weak-effect variants.
"For each disease there are probably hundreds of such variants and the genetic risk is likely to come from inheriting a large number of these variants from both parents," researcher David van Heel said in a university release Wednesday.
"If this is the case then it may never be possible to accurately predict an individual's genetic risk of these common autoimmune diseases," he said. "However, the [study] results do provide important information about the biological basis of these conditions and the pathways involved, which could lead to the identification of new drug targets."