How are mitochondrial DNA disorders typically inherited?

Mitochondrial DNA disorders are uniquely inherited because mitochondrial DNA is exclusively passed down from the mother. This occurs because the mitochondria in the sperm are typically destroyed during fertilization, meaning that only the mitochondria from the egg contribute to the mitochondria of the offspring.

Since mitochondria are present in the cytoplasm of the egg, any mutations within mitochondrial DNA will affect all of the cells of the resulting organism, leading to a maternal lineage of inheritance. As a result, both males and females can inherit mitochondrial DNA disorders, but they can only be transmitted to the next generation through the mother.

This mode of inheritance distinguishes mitochondrial disorders from those that follow typical Mendelian patterns, such as autosomal dominant or recessive inheritance, which involve contributions from both parents or specific dominant traits expressed in individuals regardless of their sex.