Beta-aminoisobutyrate

Like B-alanine, Beta-aminisobutyrate is a product of the breakdown of DNA and RNA, and can be produced by unusual bacterial activity and unusual flora (yeast) in the gastrointestinal tract.

Further metabolism of beta-aminoisobutyrate requires functional B-6 activity; therefore, elevations in this metabolite in urine may reflect poor B-6 status or impaired conversion of B-6 to active P-5-P (check other B-6 dependent markers, eg. elevated beta-alanine, leucine, isoleucine, valine, cystathionine).

Hyper-beta-aminoacidurea is a complex disorder in both metabolism and renal transport.

Elevated levels of beta-alanine cause decreased renal absorption of beta-aminoisobutyrate, taurine and sometimes gamma- aminobutyrate. Depletion of the neurotransmitter taurine, and the suppression of gamma- aminobutyrate in the nervous system can affect behavior, cognitive function and result in seizures. Hyper-beta-aminoacidurea can be associated with the following symptoms:

- tingling/burning sensations in the skin,

- headaches,

- irritability,

- uneven temper,

- fatigue and delusions.

General food intolerances and sensitivities to xenobiotics are common complaints. Patients presenting with hyper-beta-aminoacidurea should be evaluated for magnesium and zinc status (Red Blood Cell Elements), B-6 and abnormal intestinal flora (Comprehensive Stool Analysis). Dietary restriction of foods high in carnosine and anserine may be necessary. Neoplastic diseases have been documented to be associated with hyper-beta-aminoisobutyrate but an elevation in this metabolite is not diagnostic for such conditions.

Low levels of β-AIB may be seen with decreased precursors, such as valine. Dihydropyrimidine dehydrogenase deficiency is a rare inborn error of metabolism that results in lower levels of urinary β-AIB.

Beta-aminoisobutyric acid (also known as 3-aminoisobutyric acid) is a non-protein amino acid formed by the catabolism of valine and the nucleotide thymine. It is further catabolized to methylmalonic acid semialdehyde and propionyl-CoA. Levels are controlled by a vitamin B6-dependent reaction in the liver and kidneys. β-aminoisobutyric acid can also be produced by skeletal muscle during physical activity.