MSH: Birth defect that results in a partial or complete absence of the CORPUS CALLOSUM. It may be isolated or a part of a syndrome (e.g., AICARDI'S SYNDROME; ACROCALLOSAL SYNDROME; ANDERMANN SYNDROME; and HOLOPROSENCEPHALY). Clinical manifestations include neuromotor skill impairment and INTELLECTUAL DISABILITY of variable severity.,NCI: A congenital abnormality characterized by the complete absence of the corpus callosum. It may be an isolated abnormality or associated with other central nervous system abnormalities or syndromes. Clinical manifestations vary. In cases of isolated corpus callosum agenesis, symptoms may be absent or minimal. In cases that are associated with other central nervous system abnormalities or syndromes, symptoms include developmental delays, motor coordination difficulties, and vision impairment.