Читать книгу Genetic Analysis of Complex Disease - Группа авторов - Страница 44

Mitochondrial inheritance is a non‐classical pattern of single gene inheritance that is observed in conditions in which the causative allele is located in the mitochondrial DNA (mtDNA). In humans, each mitochondrion has approximately 2–10 copies of the mtDNA, which contains 37 genes. A mutation in one of these genes may be present in all copies of the mtDNA in a cell (known as homoplasmy). Alternately, a cell may contain some mtDNA with the mutation and other mtDNA without the mutation, known as heteroplasmy. The degree of heteroplasmy may vary by tissue and can influence the severity of the disease and the risk to future offspring. Mitochondria are inherited from the mother and, therefore, are referred to as having “maternal inheritance.” The risk for an affected mother to pass on the genetic defect in the mtDNA can approach 100%.