Mitochondria are the “powerhouses” of a cell, producing most of the energy that cells need to function.
In mitochondrial disease, of which there are many types, these cellular compartments cannot function properly. Because almost every cell has mitochondria, mitochondrial disease can affect every system in the body.
If you or your partner have mitochondrial disease, it’s a good idea to discuss family planning with your doctor and genetic counselor. They can help to determine your risks of transmitting the disease to your children. They can also advise on the reproductive options that are available to you to avoid this risk.
DNA and mitochondrial disease
Most of the genes that are necessary to support mitochondrial function reside within the cell nucleus. However, a small number of genes are maintained within the mitochondria themselves. A mutation in any one of these 37 genes can cause mitochondrial disease.
During reproduction, children inherit one copy of their genes from their mother, and one copy from their father. (We all have two copies of each gene.) However, they inherit their mitochondria and the genes they carry, primarily from their mother. In extremely rare cases, a child has inherited paternal mitochondria as well.
This separation of mitochondrial and cellular DNA means that if a child’s father has mitochondrial disease due to a gene contained in the mitochondria, it is very unlikely his children will inherit the disease. However, if the mother has a genetic mutation in the mitochondrial genome, all of her children are likely to inherit the disease.
If the mutations are in genes that reside in the nucleus of the cell, however, the mother or the father are equally likely to transmit the disease to their children. Depending on the inheritance pattern of the specific mitochondrial disease a parent has, the disease can be passed in a recessive or dominant manner.