What is unique about mitochondrial DNA inheritance?

Mitochondrial DNA (mtDNA) inheritance is unique because it is passed down exclusively along the maternal line. This distinctive inheritance pattern occurs because mitochondria, the energy-producing structures within cells, are inherited from the egg cell of the mother. During conception, while sperm contribute nuclear DNA to the embryo, the mitochondria from the sperm are typically not retained in the zygote. As a result, all offspring inherit their mitochondrial DNA solely from their mother, making the maternal line the source of mtDNA for any individual.

This unique mode of inheritance has significant implications in genetic studies, particularly in tracing maternal lineage and understanding hereditary conditions that can be linked to mitochondrial DNA mutations. Given that mitochondrial DNA is not influenced by paternal contributions, it provides a clearer lineage of maternal ancestry compared to nuclear DNA, which combines genetic material from both parents.