ALDH6A1 and renal cell carcinoma: A previous study showed that renal cell carcinoma results in an increased level of alanine in cells, which might be due to the downregulated expression of ALDH6A1 gene [24], thus demonstrating that the ALDH6A1 gene may encode methylmalonate semialdehyde dehydrogenase, was deficient and hence the level of alanine was increased.