What does low methylmalonic acidemia mean?

What does low methylmalonic acidemia mean?

Methylmalonic acidemia is a disorder in which the body cannot break down certain proteins and fats. The result is a buildup of a substance called methylmalonic acid in the blood. This condition is passed down through families. It is one of several conditions called an “inborn error of metabolism.”

What enzyme is deficient in methylmalonic acidemia?

Methylmalonic acidemia (MMA) is usually caused by a deficiency of the enzyme methylmalonyl-CoA mutase (MCM), a defect in the transport or synthesis of its cofactor, adenosyl-cobalamin (cblA, cblB, cblC, cblF, cblD, and cblX), or deficiency of the enzyme methylmalonyl-CoA epimerase.

What does an MMA blood test show?

An MMA test is most often used to diagnose a vitamin B12 deficiency. This test is also used to diagnose methylmalonic acidemia, a rare genetic disorder. Symptoms of this disorder can range from mild to severe and may include vomiting, dehydration, developmental delays, and intellectual disability.

Can you have B12 deficiency with normal MMA?

As the natural course of vitamin B12 deficiency is not well-known, it cannot be excluded that participants with low serum B12 but normal MMA may be in the early, still asymptomatic phase of their deficiency.

How is MMA diagnosed?

Determination of organic acids in urine and the acylcarnitine profile in blood are the most commonly used investigations to detect MMA and PA. Determination of amino acid concentrations may help in diagnosis and treatment. In addition total plasma homocysteine allows differentiation between the various types of MMA.

What is a critically low B12 level?

Values of less than 160 pg/mL (118 pmol/L) are a possible sign of a vitamin B12 deficiency. People with this deficiency are likely to have or develop symptoms. Older adults with a vitamin B12 level less than 100 pg/mL (74 pmol/L) may also have symptoms.

Is the Mut–enzymatic subtype associated with pathogenic variants in the mutprotein?

The mut–enzymatic subtype is known to be associated mostly, but not exclusively, with pathogenic variants in the cobalamin binding domainof the mutprotein.

How many allelic variants are there in methylmalonic acidemia (MMA)?

Martínez MA, Rincón A, Desviat LR, Merinero B, Ugarte M, Pérez B. Genetic analysis of three genes causing isolated methylmalonic acidemia: identification of 21 novel allelic variants. Mol Genet Metab. 2005;84:317–25.

How are malonic acid and methylmalonic acid (MMA) elevated in CMAMMA?

Patients with CMAMMA show high malonic acid (MA) and methylmalonic acid (MMA) levels in their urine or plasma, with MMA excretion typically being higher than MA excretion (MMA/MA >5). Because C3 (propionylcarnitine) is not elevated, infants with CMAMMA are not detected by newborn screening based on a dried blood spot acylcarnitine analysis.