Mitochondrial Inheritance - Example

Pedigree

The mitochondria have their own genome consisting of a single circular strand of DNA on which are located a few genes that are involved in oxidative phosphorylation. This mitochondrial DNA is inherited from the mother. Some CNS, muscle, and hearing disorders are due to mutations in mitochondrial genes. Affected males never transmit these disorders.

MELAS

This disorder results from a mutated mitochondrial gene involved with oxidative phosphorylation. The disease is called mitochondrial encephalopathy and lactic acidosis with stroke-like episodes (MELAS) and manifests with progressive muscular weakness and central nervous system deterioration with ataxia and epilepsy. The affected person typically has a series of episodes resembling cerebrovascular accidents and does not survive middle age.