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: Biochemistry
Mitochondria gene (True statement)a) Paternal transmissionb) Maternal transmissionc) Mendelian inheritanced) Mitochondrial myopathy 
Select and explain. 
A. c, B. bd, C. ab, D. ac
B: bd
Answer: B: bd 
Explanation: Mitochondrial DNA is always maternally inherited.
Important mitochondrial diseases are mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS), Leber hereditary optic neuropathy, myoclonic epilepsy with ragged-red fibers, Leigh syndrome, Pearson syndrome, keams-sajre syndrome, chronic progressive external ophthalmoplegia and NARP (neurogenic weakness with ataxia & retinitis pigmentosa).