This gene is one of three related genes that have 2-hydroxyacid oxidase activity yet differ in encoded protein amino acid sequence, tissue expression and substrate preference. Subcellular location of the encoded protein is the peroxisome. Specifically, this gene is expressed primarily in liver and pancreas and the encoded protein is most active on glycolate, a two-carbon substrate. The protein is also active on 2-hydroxy fatty acids. The transcript detected at high levels in pancreas may represent an alternatively spliced form or the use of a multiple near-consensus upstream polyadenylation site. HAO1 (Hydroxyacid Oxidase 1) is a Protein Coding gene. Diseases associated with HAO1 include Lactocele and Primary Hyperoxaluria. Among its related pathways are Glyoxylate metabolism and glycine degradation and Peroxisome. GO annotations related to this gene include receptor binding and FMN binding. An important paralog of this gene is HAO2.