HDHD3 (haloacid dehalogenase-like hydrolase domain containing 3) is a 251 amino acid protein that belongs to the HAD-like hydrolase superfamily, which contains a group of hydrolase enzymes that differ from the a/∫ hydrolase family based on structure. This family of hydrolase enzymes includes L-2-haloacid dehalogenase, epoxide hydrolases and phosphatases. HDHD3 is encoded by a gene located on human chromosome 9q32. Chromosome 9 consists of about 145 million bases, 4% of the human genome and encodes nearly 900 genes. Thought to play a role in gender determination, deletion of the distal portion of 9p can lead to development of male to female sex reversal, the phenotype of a female with a male X,Y genotype.