title: A treatable metabolic cause of encephalopathy: cobalamin C deficiency in an 8-year-old male.
abstract: Neurologic regression in a previously healthy child may be caused by metabolic or neurodegenerative disorders, many of which have no definitive treatment. We report a case of a previously healthy 8-year-old boy who presented with a month-long history of waxing and waning encephalopathy and acute regression, followed by seizures. Evaluation for a metabolic disorder revealed methylmalonic acidemia and hyperhomocysteinemia of the cobalamin C type due to a single, presumed homozygous pathogenic c.394 C>T mutation in the MMACHC gene. With the appropriate diet restrictions and vitamin replacement, he improved significantly and returned to his premorbid level of behavior. This case illustrates an unusual presentation of a treatable metabolic disorder and highlights the need to consider cobalamin defects in the differential diagnosis of healthy children with neurologic regression.
authors.affiliation: Divisions of Neurology and jkrueger@luriechildrens.org.
authors.forename: Jena M
authors.initials: JM
authors.lastname: Krueger
authors.affiliation: Divisions of Neurology and Ruth D. and Ken M. Davee Pediatric Neurocritical Care Program, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Juan
authors.initials: J
authors.lastname: Piantino
authors.affiliation: Ruth D. and Ken M. Davee Pediatric Neurocritical Care Program, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Craig M
authors.initials: CM
authors.lastname: Smith
authors.affiliation: Genetics, Birth Defects, and Metabolism, and.
authors.forename: Brad
authors.initials: B
authors.lastname: Angle
authors.affiliation: Divisions of Neurology and Ruth D. and Ken M. Davee Pediatric Neurocritical Care Program, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Charu
authors.initials: C
authors.lastname: Venkatesan
authors.affiliation: Divisions of Neurology and Ruth D. and Ken M. Davee Pediatric Neurocritical Care Program, Ann and Robert H. Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Wainwright
mesh_terms: D001928:Brain Diseases, Metabolic / Q000209:etiology* / Q000628:therapy*; D002648:Child; D006801:Humans; D008297:Male; D014806:Vitamin B 12 Deficiency / Q000150:complications*
keywords: cobalamin C deficiency; encephalopathy; inborn error of metabolism