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Inherited variants of MYH associated with somatic G:C→T:A mutations in colorectal tumors

Inherited variants of MYH associated with somatic G:C→T:A mutations in colorectal tumors Inherited defects of base excision repair have not been associated with any human genetic disorder, although mutations of the genes mutM and mutY, which function in Escherichia coli base excision repair, lead to increased transversions of G:C to T:A 1,2,3,4 . We have studied family N, which is affected with multiple colorectal adenomas and carcinoma but lacks an inherited mutation of the adenomatous polyposis coli gene (APC) that is associated with familial adenomatous polyposis 5 . Here we show that 11 tumors from 3 affected siblings contain 18 somatic inactivating mutations of APC and that 15 of these mutations are G:C→T:A transversions—a significantly greater proportion than is found in sporadic tumors or in tumors associated with familial adenomatous polyposis. Analysis of the human homolog of mutY, MYH 6 , showed that the siblings were compound heterozygotes for the nonconservative missense variants Tyr165Cys and Gly382Asp. These mutations affect residues that are conserved in mutY of E. coli (Tyr82 and Gly253). Tyrosine 82 is located in the pseudo-helix-hairpin-helix (HhH) motif and is predicted to function in mismatch specificity 7 . Assays of adenine glycosylase activity of the Tyr82Cys and Gly253Asp mutant proteins with 8-oxoG:A and G:A substrates show that their activity is reduced significantly. Our findings link the inherited variants in MYH to the pattern of somatic APC mutation in family N and implicate defective base excision repair in predisposition to tumors in humans. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Genetics Springer Journals

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References (31)

Publisher
Springer Journals
Copyright
Copyright © 2002 by Nature Publishing Group
Subject
Biomedicine; Biomedicine, general; Human Genetics; Cancer Research; Agriculture; Gene Function; Animal Genetics and Genomics
ISSN
1061-4036
eISSN
1546-1718
DOI
10.1038/ng828
Publisher site
See Article on Publisher Site

Abstract

Inherited defects of base excision repair have not been associated with any human genetic disorder, although mutations of the genes mutM and mutY, which function in Escherichia coli base excision repair, lead to increased transversions of G:C to T:A 1,2,3,4 . We have studied family N, which is affected with multiple colorectal adenomas and carcinoma but lacks an inherited mutation of the adenomatous polyposis coli gene (APC) that is associated with familial adenomatous polyposis 5 . Here we show that 11 tumors from 3 affected siblings contain 18 somatic inactivating mutations of APC and that 15 of these mutations are G:C→T:A transversions—a significantly greater proportion than is found in sporadic tumors or in tumors associated with familial adenomatous polyposis. Analysis of the human homolog of mutY, MYH 6 , showed that the siblings were compound heterozygotes for the nonconservative missense variants Tyr165Cys and Gly382Asp. These mutations affect residues that are conserved in mutY of E. coli (Tyr82 and Gly253). Tyrosine 82 is located in the pseudo-helix-hairpin-helix (HhH) motif and is predicted to function in mismatch specificity 7 . Assays of adenine glycosylase activity of the Tyr82Cys and Gly253Asp mutant proteins with 8-oxoG:A and G:A substrates show that their activity is reduced significantly. Our findings link the inherited variants in MYH to the pattern of somatic APC mutation in family N and implicate defective base excision repair in predisposition to tumors in humans.

Journal

Nature GeneticsSpringer Journals

Published: Jan 30, 2002

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