The correct answer is B.
Keywords: Agyria, lissencephaly,
Agyria is lissencephaly. Mutations in ARX, DCX and LIS1, as well as terminal 17p
deletions cause lissencephaly. EMX2 mutations cause schizencephaly, ruling our D.
Since there are no dysmorphic features, 17p deletions (C, which cause Miller-Dieker
syndrome with craniofacial dysmorphisms) can be ruled out. Similarly, since the patient
has normal genitalia, that rules out ARX mutations (A). Isolated lissencephaly can be
caused by LIS1 or DCX mutations. Since the mother has seizures, but clearly no
lissencephaly, and the patient is male, the most likely explanation is (B) DCX mutation,
not (E) LIS1 mutation.