Identical twins are more alike than fraternal twins not only because of the similarity of their DNA sequence, but also because the pattern of chemical modifications that regulate expression of their DNA is also more similar, suggests a study published online online in Nature Genetics.
Gene expression is regulated by a variety of chemical modifiers, including methyl groups, which have been characterized across whole genomes in recent years. Art Petronis and colleagues carried out the first genome-wide study of inter-individual differences in DNA methylation by profiling tissues from both identical and fraternal twins. They show that fraternal twins, who have different genomes, also have more DNA methylation differences than identical twins, who have identical genomes. The authors suggest that variation in inherited DNA methylation profiles could make a substantial contribution to variation in phenotype.
Art Petronis (Centre for Addiction and Mental Health, Toronto, Ontario, Canada)
Abstract available online.
(C)Nature Genetics press release.
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