Identical twins look the same and are nearly genetically identical, but environmental factors and the resulting cellular changes could cause disease in one sibling and not the other. In a study published online in Genome Research (www.genome.org), scientists have studied twins discordant for the autoimmune disease lupus, mapping DNA modifications across the genome and shedding light on epigenetic changes that may play a role in the disease.
Because the genetic makeup of monozygotic twins (commonly known as identical twins) is nearly identical, phenotypic traits and heritable diseases are often concordant, manifesting in both siblings. However, some phenotypes and diseases such as autoimmune disease can arise in only one sibling, suggesting other factors such as environment likely play a role in determining phenotypic differences.
Epigenetic modifications, cellular changes that can influence expression of genes, are now widely recognized to influence phenotype and frequently occur in disease. Furthermore, environmental factors such as diet and chemical exposure can change the epigenetic status of genes. Recent research has identified epigenetic modifications at several aberrantly regulated genes in autoimmune diseases such as systemic lupus erythematosus (SLE), and other studies have suggested that epigenetic differences are associated with phenotypic discordance between identical twins.
In this work, researchers from Spain and the United States performed the first genome-wide high-throughput analysis of a specific epigenetic modification, DNA methylation, in the context of autoimmune disease. Taking advantage of the identical genetic background in monozygotic twins, the group directly compared DNA methylation in healthy twins and twins discordant for autoimmune diseases, including SLE, looking for changes that could be related to pathogenesis in one sibling and not the other.
In the case of SLE, the group found wi
|Contact: Peggy Calicchia|
Cold Spring Harbor Laboratory