MAT1A and metabolic dysfunction-associated steatohepatitis: Furthermore, we found that adenosylhomocysteinase (AHCY), an enzyme downstream of GNMT in the transmethylation pathway, was downregulated and that AdoMet biosynthetic enzyme, methionine adenosyltransferase 1A (MAT1A), was significantly upregulated in NASH (Figure 5A).