by Playfuls Staff |
5th December 2006
U.S. scientists have discovered mutations in a gene known as SOS1 account for many cases of Noonan syndrome, a common [more] childhood genetic disorder.
"Although previous work had identified mutations in the PTPN11 gene as the cause of Noonan syndrome in nearly 50 percent of cases (and mutations in an oncogene known as KRAS in a small subset of severe cases) the identity of the gene or genes responsible for fully half the cases had not been elucidated," said Dr. Benjamin Neel of Harvard Medical School, a co-senior author of the study.
To identify candidate genes, researchers at Harvard Medical School and the Beth Israel Deaconess Medical Center conducted a genetic analysis of more than 100 children with Noonan syndrome.
From that group, SOS1 mutations were found in approximately 20 percent of the cases. After modeling the positions of the mutations on crystal structures of SOS1, the scientists discovered they promoted excessive activation of RAS and its downstream target, MAP kinase -- the same pathway activated by PTPN11 mutations.
"These results are the first example of activating mutations in an exchange factor in human disease," noted Neel.
The study is explained in the December issue of Nature Genetics.
© 2006 UPI
