NBME 1 Block 2 Question 46 - hnin

[ArchivalUser]

(Sorry for not posting the pedigree)
In a family represented by pedigree, affected persons have a disease characterized by mitochondrially inherited late onset optic atrophy.Assuming that the family and personal medical history of a partner is unremarkable, the risk for optic atrophy to develop in the male child of IV- 9 is closet to
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

My answer is A
Can anyone correct if I wrong?

[ArchivalUser]

You are correct. answer is A. Leber's hereditary optic neuropathy is maternally inherited (Mitochondrial inheritance). Therefore the pedigree shows a male, so he cannot transmit the dz to any of his offspring, making the prob. 0%.

[ArchivalUser]

Thank you sleek.