What is the pattern of inheritance for Leber's hereditary optic neuropathy (LHON)?

Leber's hereditary optic neuropathy (LHON) has a pattern of inheritance that is classified as mitochondrial. This is due to the fact that LHON arises from mutations in mitochondrial DNA, which is inherited exclusively from the mother. Mitochondrial DNA is passed down through the maternal line, meaning that the effects of LHON can be seen in both male and female descendants, but all affected individuals inherit the mutation from their affected mother.

This type of inheritance is distinct in that it does not follow the typical Mendelian patterns associated with autosomal or X-linked traits. In mitochondrial diseases, the severity and expressivity of symptoms can vary significantly among individuals, even within the same family, which is a characteristic feature of mitochondrial inheritance.

Understanding the pattern of inheritance for LHON is crucial for genetic counseling and predicting the risk of transmission to future generations, as all offspring of an affected female may carry the mitochondrial mutations.