EXDL1 is a 514 amino acid protein that belongs to the EXD1 family and contains one 3'-5' exonuclease domain. Existing as two alternatively spliced isoforms, the gene encoding EXDL1 maps to human chromosome 15q15.1 and mouse chromosome 2 E5. Encoding more than 700 genes, chromosome 15 is made up of approximately 106 million base pairs and is about 3% of the human genome. Angelman and Prader-Willi syndromes are associated with loss of function or deletion of genes in the 15q11-q13 region. In the case of Angelman syndrome, this loss is due to inactivity of the maternal 15q11-q13 encoded UBE3A gene in the brain by either chromosomal deletion or mutation. In cases of Prader-Willi syndrome, there is a partial or complete deletion of this region from the paternal copy of chromosome 15.