Summary
Mitochondrial DNA is passed almost exclusively from the mother, giving maternal inheritance patterns.
In depth
Sperm mitochondria are usually destroyed in the embryo, so mtDNA comes from the mother. Both sons and daughters inherit it but only daughters pass it on. Cells hold many mtDNA copies, so heteroplasmy (a mixture of normal and mutant) affects severity.
Mitochondrial DNA is used to trace maternal lineages in human history.
Human mtDNA has 37 genes for 13 proteins, 22 tRNAs and 2 rRNAs. Because there are hundreds to thousands of copies per cell, mutations can be heteroplasmic, a mixture of normal and mutant, and disease appears only when the mutant fraction crosses a threshold, which differs among tissues. The bottleneck in the germline makes offspring vary widely in mutant load.
Mitochondrial disorders include MELAS, MERRF and Leber hereditary optic neuropathy. Mitochondrial replacement therapy, where a donor egg's mitochondria are used, was approved in the UK in 2015 and creates children with DNA from three people.
Example: mtDNA analysis traced all living humans to a mitochondrial Eve who lived in Africa about 150,000 to 200,000 years ago, which does not mean she was the only woman then.
Frequently asked questions
What is Mitochondrial Inheritance?
Mitochondrial DNA is passed almost exclusively from the mother, giving maternal inheritance patterns.
Which area of biology covers Mitochondrial Inheritance, and how advanced is it?
Mitochondrial Inheritance is one of the 54 topics in Genetics. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Pedigree Analysis, Trinucleotide Repeat Disorders, X-Chromosome Inactivation.
Can you give an example of Mitochondrial Inheritance?
Leber hereditary optic neuropathy follows a maternal pattern.
What should I learn before Mitochondrial Inheritance?
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Mitochondrial Inheritance. Advanced topics assume the Intermediate vocabulary.
What topics are related to Mitochondrial Inheritance?
The closest topics to Mitochondrial Inheritance are Pedigree Analysis, Trinucleotide Repeat Disorders, X-Chromosome Inactivation, Penetrance and Expressivity. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Mitochondrial Inheritance?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Mitochondrial Inheritance. To practise the whole of Genetics, use the Genetics quiz.
How is Mitochondrial Inheritance different from Pedigree Analysis?
Mitochondrial Inheritance: Mitochondrial DNA is passed almost exclusively from the mother, giving maternal inheritance patterns. Pedigree Analysis: Family trees that trace a trait across generations to infer dominant, recessive or sex-linked inheritance. Read both side by side and note what each one explains.
How should I study Mitochondrial Inheritance step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Pedigree Analysis and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.