4-trimethylaminobutyraldehyde dehydrogenase

ALDH9A1 encodes 4-trimethylaminobutyraldehyde dehydrogenase (TMABA-DH), an aldehyde dehydrogenase that catalyzes NAD-dependent oxidation of aldehydes derived from biogenic amines and polyamines. It is notably efficient at converting gamma-trimethylaminobutyraldehyde into gamma-butyrobetaine (UniProt: P49189).

The enzyme participates in polyamine and carnitine metabolism, pathways relevant to cellular energy and membrane integrity. No disease associations are documented in UniProt for ALDH9A1; however, it has been identified in Alzheimer's disease proteomic studies.

ALDH9A1 is upregulated in post-mortem Alzheimer's disease brain tissue compared to age-matched controls, with a mean log2 fold-change of 0.50 across subcellular fractions in TMT-labeled quantitative proteomics (Chaparral AD proteomics). The modest elevation suggests altered aldehyde detoxification or polyamine metabolism in the AD brain, though functional consequences remain to be established.