Semilobar holoprosencephaly in a 12-month-old baby boy born to a primigravida patient with type 1 diabetes mellitus: a case report

Background Holoprosencephaly is a rare spectrum of cephalic disorders resulting from a failure or incomplete division of the embryonic forebrain into distinct cerebral hemispheres. It is the most common brain malformation with an incidence of 1:250 during embryogenesis; however, owing to the associated high rates of spontaneous abortion the incidence is 1:16,000 among live deliveries. Pathogenesis of holoprosencephaly is complex and heterogeneous involving genetic abnormalities, teratogenic exposures, and syndromic associations. Among the teratogenic exposures, maternal diabetes is a well-established risk factor associated with a 200-fold increased incidence of holoprosencephaly.