A gene in the mitochondrial DNA can cause Kearns-Sayre syndrome (KSS). A large
sample of different types of somatic cells was removed from a male with KSS, tested,
and were all found to have the disease allele.
The only type of mitochondrial DNA that was found in somatic cells from the mother
was mitochondrial DNA that did not have the KSS allele.
The best hypothesis to explain these results is that there was a mutation in the DNA
causing KSS that first occurred in the
man's spermatocytes
mother's somatic cells
mother's oocytes
man's somatic cells