Precocious cerebral development associated with agenesis of the corpus callosum in mid-fetal life: a transient syndrome?

Four fetal brains are described in which the cerebrum showed precocious sulcus formation. The fetuses were 14, 17, 18 (15), and 19 (15-16) weeks of gestational age (age in parentheses according to developmental parameters). Associated lesions were characterized by insufficient insular formation and agenesis of the corpus callosum. Cases 1 and 3 had no familial anomalies, while a sib of case 2 had rhombencephalic malformations and a sib of case 4 lissencephaly. Case 2 showed further brain malformation including a migration disorder in the cerebrum and case 3 was associated with a Turner syndrome. The precociously formed sulci may be covered during further development of the brain so that this may well be a transient syndrome that occurs in mid-fetal life.