Brief report: childhood disintegrative disorder as a likely manifestation of vitamin B12 deficiency.

Childhood disintegrative disorder is a rare disorder, characterized by regression of acquired skills after a period of normal development. The case of childhood disintegrative disorder presented here was found to have vitamin B12 deficiency and hyperhomocysteinemia on extensive evaluation to find a probable cause for regression. This case illustrates the need for a thorough evaluation of all cases of childhood disintegrative disorder so that treatable causes of regression, like vitamin B12 deficiency, are not missed.