MedlinePlus Medical Encyclopedia: Methylmalonic acidemia

Skip navigation


Medical Encyclopedia
Other encyclopedia topics:	A-Ag Ah-Ap Aq-Az B-Bk Bl-Bz C-Cg Ch-Co Cp-Cz D-Di Dj-Dz E-Ep Eq-Ez F G H-Hf Hg-Hz I-In Io-Iz J K L-Ln Lo-Lz M-Mf Mg-Mz N O P-Pl Pm-Pz Q R S-Sh Si-Sp Sq-Sz T-Tn To-Tz U V W X Y Z 0-9

Methylmalonic acidemia

Contents of this page:
Definition Causes, incidence, and risk factors Symptoms Signs and tests Treatment	Expectations (prognosis) Complications Calling your health care provider Prevention

Definition

Methylmalonic acidemia is an inherited metabolic disorder, usually diagnosed in infancy, that causes the accumulation of methylmalonic acid in the body and can lead to severe metabolic disturbances.

Causes, incidence, and risk factors

A defect in the metabolic conversion of methymalonyl-coenzyme A to succinyl-CoA leads to a build up of methylmalonic acid in the body. The disease is usually diagnosed in the first year of life because it can cause seizures and stroke. Protein in the diet may worsen this condition, so babies who have it may appear normal at birth but show symptoms once they increase their protein intake.

This autosomal recessive disorder (the defective gene must be inherited from both parents) occurs in 1 in 25,000 to 48,000 people. The true rate of occurrence of the disease may be higher, because many neonatal deaths may be caused by undiagnosed metabolic disorders. Both boys and girls are equally affected.

Symptoms

vomiting
dehydration
lethargy
seizures
failure-to-thrive
recurrent infections with Candida sp.
progressive encephalopathy
developmental delays

Signs and tests

Tests:

serum electrolytes
blood gas for acidosis
serum ammonia levels (see ammonia - test)
serum and urine tests for amino acids and organic acids
serum methylmalonic acid levels
enzyme analysis of fibroblasts for the specific enzyme abnormality
CBC for neutropenia, anemia, and thrombocytopenia
CT scan or MRI of the brain following a seizure

Treatment

Treatment consists of dietary supplementation with cobalamin, carnitine, and protein restriction.

If cobalamine supplementation doesn't help, a trial of a diet restricting isoleucine, threonine, methionine, and valine may be useful.

Expectations (prognosis)

Unfortunately, affected patients may not survive their first attack.

Complications

coma
death

Calling your health care provider

Parents or care-givers of a child with a first seizure should immediately seek medical attention. Infants with failure-to-thrive or developmental delays should see a pediatrician. Adults and children with strokes or acute mental status changes should seek immediate medical attention.

Prevention

Following a low-protein maintenance diets and avoiding infection help to reduce recurrent attacks of acidemia. Parents of a child with this disorder or couples desiring children who have a known family history of this disorder should seek information on genetic counseling.

Update Date: 10/30/2003

Updated by: Philip L. Graham III, M.D., M.S., F.A.A.P., Department of Pediatrics, Children's Hospital of New York, Columbia University, New York, NY. Review provided by VeriMed Healthcare Network.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 2002 A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.