Genomic imprinting
A chromosomal deletion causes a disorder only when it is inherited from the father. The best explanation is that:
Answer B: explanation for every choice
A
X-linked inheritance follows sex, not the parent of origin in this way.
B
Correct. In imprinted regions, only one parent's copy is active. Losing the active paternal copy leaves no working gene, as in Prader–Willi syndrome.
C
Mitochondrial DNA is inherited from the mother, not the father.
D
Incomplete penetrance would not depend consistently on which parent passed on the deletion.
TakeawayImprinting: expression depends on which parent the allele came from.
Next question →
Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb168.