spartylglucosaminuria ( commonly referred to as AGU) is an inherited disease that is characterized by a decline in mental functioning, accompanied by an increase in skin bone and joint issues. This disease is caused by a defect in an enzyme known as aspartylglucosaminidase. This enzyme plays a significant role in our body because it aids in breaking down certain sugars ( for example oligosaccharides) that are attached to specific proteins ( for example: glycoproteins). Aspartylglucosaminuria itself is characterized as a lysosomal disease because it does deal with inadequate activity in an enzymes function.[1] Aspartylglucosaminidase function is to break down glycoproteins. These proteins are most abundant in the tissues of the body and in the surfaces of major organs, such as: the liver, spleen, thyroid and nerves. When glycoproteins are unable to be broken down then it causes aspartylglucosaminidase to back up in the lysosomes along with other substances. This back up causes damage to the tissues and organs that is progressive.[2]