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.

Diagnosis of cobalamin C deficiency with renal abnormality from onset in a Chinese child by next generation sequencing: A case report

“…Typical medications for MMA include vitamin B12, L-carnitine, betaine, calcium foliate, vitamin B8 and special milk (excluding valine, threonine and methionine) ( 25 ). It has previously been suggested that angiotensin converting enzyme inhibitor should be prescribed for MMA patients with renal damage, as this drug may aid to reduce proteinuria and promote the recovery of renal function ( 26 ).…”