In Leber's disease (LHON),degeneration of the optic nerve results in blindness due to a defect in NADH dehydrogenase affecting electron transport.If this is due to a mutation in a mitochondrial gene,which combination of effects would you expect to see when doing a pedigree analysis of a family with LHON? i. variable expressivity
Ii. incomplete penetrance
Iii. progressive blindness over time
Iv. maternal inheritance
V. diminished muscle mass

Question

Quizplus · Accepted Answer

LHON is caused by a mutation in a mitochondrial gene, which is only maternally inherited. Therefore, IV is correct. The degeneration of the optic nerve leads to progressive blindness over time, making III correct. The severity of the disease can vary from person to person, resulting in variable expressivity (I), and the defect in electron transport can have incomplete penetrance (II). Diminished muscle mass is not a characteristic of LHON, so V is incorrect. Therefore, the correct combination is i, ii, iii, and iv, making choice E the best answer.

In Leber's Disease (LHON),degeneration of the Optic Nerve Results in Blindness