Medical Definition of biallelic
: of, relating to, or affecting both alleles of a gene The risk of colorectal cancer among carriers of biallelic mutations appears to be close to 100% by 60 years of age …—William D. Foulkes, The New England Journal of Medicine, 13 Nov. 2008 This mode of oncogenesis differs from the inactivation of most tumor-suppressor genes, which are biallelic—that is, one allele is inactivated in the germ line, followed by mutation of the second allele at the somatic-cell level.—Roel Nusse, Science, 18 May 2007
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