4-fumarylacetoacetate + H2O = acetoacetate + fumarate + H(+) Amino-acid degradation; L-phenylalanine degradation; acetoacetate and fumarate from L-phenylalanine: step 6/6. Homodimer. Mainly expressed in liver and kidney. Lower levels are also detected in many other tissues. The disease is caused by variants affecting the gene represented in this entry. Belongs to the FAH family.