Sagittal MRIs for patients 1–5 showing abnormalities in patients 2, 3, and 5. (A) MRI of patient 1 shows a normal anterior and posterior pituitary, with no other anomalies. (B) MRI of patient 2 (a twin) reveals global cerebral hemisphere atrophy with a small posterior pituitary, a thin corpus callosum, and small optic nerves. (C) MRI of patient 3 (a twin) reveals generalized underdevelopment of the brain. The posterior pituitary is normal with small optic nerves and a thin corpus callosum. (D) MRI of patient 4 shows a normal anterior and posterior pituitary, with no other anomalies. (E) MRI of patient 5 shows generalized underdevelopment of the brain and a very thin corpus callosum. AP, anterior pituitary; CC, corpus callosum; ON, optic nerve; PP, posterior pituitary; WML, white matter loss.