Magazine article Science News

Laser Gene-Mapping Yields Clues in Diabetes

Magazine article Science News

Laser Gene-Mapping Yields Clues in Diabetes

Article excerpt

As difficult as geneticists found it to pinpoint the gene for Huntington's disease and the gene for cystic fibrosis (SN: 7/10/93, p.20), those searches seem simple compared to the quests for the genetic bases of more common disorders, such as diabetes and schizophrenia. Several genes and environmental factors seem to play a role in the development of these illnesses, making it difficult to tease out specific causes.

A refinement of a gene-mapping technique now promises to simplify these quests and has already enhanced the understanding of type I, or insulin-dependent, diabetes. "We have proved for the first time that type I diabetes is a polygenic disease," says John A. Todd of the University of Oxford in England.

Other studies had indicated that a form of a gene responsible for an immune-system molecule called HLA class II and a version of the insulin gene were important in this disease. The new data confirm HLA's key role -- HLA genes account for about 40 percent of an individual's risk of developing type I diabetes. The insulin gene seems no more important than about a dozen other genes, Todd said last week at the Jackson Laboratory in Bar Harbor, Maine, during the Short Course in Medical and Experimental Mammalian Genetics.

If these findings hold up, then testing for this HLA gene may help identify people at high risk of getting this disease, he adds.

To home in on a gene, scientists first identify ever smaller sections of the chromosome on which it resides. For several years, gene mappers have used DNA signposts called microsatellite repeats as markers to delineate these sections. …

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