| Gene mutation linked to hereditary
type 2 diabetes
NEW YORK (Reuters Health) - Type 2 diabetes, in which the problem
stems from poor response to insulin rather than a lack of insulin,
is usually an acquired disorder often related to obesity. However,
a rare form of type 2 diabetes is hereditary, and now scientists
think they've uncovered the genetic culprit.
As reported in this week's issue of the journal Science, they identified
a missense mutation in a gene called AKT2 in a family whose members
inherited severe insulin resistance and type 2 diabetes.
Dr. Stephen O'Rahilly, at the University of Cambridge in the UK,
and colleagues had screened DNA from 104 unrelated subjects with
severe insulin resistance. They found that one participant -- 34-year
old non-obese women who developed diabetes at age 30 -- had a mutation
in the AKT2 gene.
The researchers then identified three maternal relatives who had
the same mutation and had greatly increased levels of insulin. Two
of the three had developed diabetes while in their late 30s.
The mutation was not found in three other normal first-degree relatives
or in 1500 Caucasian control subjects.
Animal experiments showed that this mutation impairs fat production.
Consistent with this observation, the original subject with the
mutation had a 35 percent lower body fat composition than other
women of similar weight and height.
"These findings demonstrate the central importance of AKT
signaling to insulin sensitivity in humans," the authors write,
which should lead to "important clues to understanding more
common forms" of diabetes.
SOURCE: Science May 28, 2004.
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