This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Mitochondrial DNA (mt- DN(A) is known for all except - 
Select and explain. 
A. Maternal inheritance, B. Heteroplasmy, C. Leber hereditary optic neuropathy is the prototype, D. Nemaline myopathy results due to mutations in mt- DNA
D: Nemaline myopathy results due to mutations in mt- DNA
Answer: D: Nemaline myopathy results due to mutations in mt- DNA 
Explanation: Ans. is 'd' i.e., Nemaline myopathy results due to mutations in mt- DNA o Nemaline myopathy is not a mitochondria] disorder. o Mitochondrial DNA is always maternally inherited. o Heteroplasmy is the presence of mixture of more than one type of an organelle genome (mt- DNA) within a cell or individual. It is a factor for the severity of mitochondrial disease, since every eukaryotic cell contains many hundreds of copies of mt- DNA; it is possible and indeed very frequent for mutations to affect only some of the copies, while the remaining ones are unaffected.