Kearns-Sayre syndrome (KSS) results in progressive loss of vision and hearing, as well as heart defects. What is the genetic basis for this disease?
A) ATP builds up and runs the electron transport chain backwards.
B) Too much sunlight damages mtDNA.
C) Reactive oxygen species mutate DNA.
D) Ageing shortens the telomeres of the mitochondrial DNA.
E) Deletions occur in mtDNA, and the proportion of defective mtDNAs increases as the severity of the symptoms increases.
Answer: E
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