How AGU Affects the Body

AGU affects children both cognitively and physically. Aspects of the disease may include:

Science Behind AGU

The underlying cause of AGU is found in an individual’s chromosomal structure. In humans, each cell contains 23 pairs of chromosomes for a total of 46: 23 from their mother and 23 from their father. The first 22 pairs of chromosomes are called autosomes, and they look the same in both males and females.  The 23rd pair are called sex chromosomes, which are different between males and females. Females have two copies of the X chromosomes (XX), and males have one X and one Y chromosome (XY). A pathogenic variant in a gene on one of the first 22 non-sex chromosomes can lead to an autosomal disorder.




Autosomal recessive describes one of several ways that a disorder or disease is passed down through families. An autosomal recessive disorder occurs when a child inherits two copies of an abnormal gene, one from the mother and one from the father. The biological parents oftentimes have no symptoms of disease because the one functional gene is able to compensate for the defective gene. This means that two healthy people can produce a child or multiple children with the same genetic disorder.

AGU is inherited in an autosomal recessive pattern, meaning both copies of the AGA gene variant (one from each parent) must be present in the person diagnosed with AGU.





Healthy AGA Gene

People with AGU have two defective copies of the AGA gene. The AGA gene provides the body with instructions for building the AGA enzyme, aspartylglucosaminidase, which is important in breaking down aspartylglucosamine. When the AGA enzyme is built correctly, aspartylglucosamine is broken down in the lysosomes and waste is recycled or disposed of properly resulting in normal cellular function.

AGU Gene

When there are two defective copies of the AGA gene, the body creates a defective AGA enzyme that cannot perform an essential function of clearing toxic waste from the lysosomes and ultimately leads to cell death. Over time, this accumulated cell death in people with AGU leads to progressive damage in the brain and other organs.

Additional information on the AGA gene can be found here.


  1. Lokko, H. N., & Stern, T. A. (2015). Regression: Diagnosis, evaluation, and management. The Primary Care Companion for CNS Disorders, 17(3). Retrieved June 5, 2019, from link.
  2. Arvio, M., & Mononen, I. (2016). Aspartylglycosaminuria: a review. Orphanet Journal of Rare Diseases, 11(162). Retrieved June 5, 2019, from link.

Additional Sources:

  1. Burt, A. D., Ferrell, L. D., & Hübscher, S. G. (Eds.). (2018). Macsween’s Pathology of the Liver (7th Edition). Amsterdam, NL: Elsevier Ltd.
  2. N(4)-(beta-N-acetylglucosaminyl)-L-asparaginase (n.d.). Retrieved June 5, 2019, from link.
  3. AGA Gene. Retrieved June 5, 2019, from link.