What is the primary route of inheritance for diseases with mitochondrial DNA mutations?

Mitochondrial DNA mutations are inherited through maternal lineage, which means that only mothers can pass these mutations on to their offspring. This is due to the fact that the mitochondria, which carry their own DNA, are predominantly inherited from the egg. When an egg is fertilized, the sperm contributes its nuclear DNA, but the mitochondria from the sperm are typically destroyed after fertilization. As a result, any mitochondrial diseases caused by mutations residing in the mitochondrial DNA will be transmitted from mother to child, and both sons and daughters can be affected.

This unique pattern of inheritance explains why diseases associated with mitochondrial DNA mutations are characterized by traits that can appear in multiple generations through the maternal line. Members of the affected maternal lineage may exhibit symptoms or findings associated with mitochondrial disorders, reflecting the maternal transmission. Thus, recognizing maternal inheritance is crucial for understanding the pathophysiology and genetic counseling of mitochondrial diseases.