Mucopolysaccharidosis type III (MPS III) is a group of inherited disorders where the body has trouble breaking down certain substances.
Also known as Sanfilippo syndrome, it mainly affects the brain and spinal cord. Individuals with MPS III may appear normal at birth, but over time, they develop problems with speech, behavior, and movement. Symptoms can vary, with some individuals experiencing mild effects and others facing more severe challenges. Unfortunately, there is currently no cure for MPS III, and treatments focus on managing symptoms to improve the quality of life for affected individuals.
This group of conditions is caused by pathogenic (disease-causing) variants in the SGSH (type IIIA and the most severe), NAGLU (type IIIB), and HGSNAT (type IIIC) genes and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition. The risk of being a carrier is based on a person’s ancestry or ethnic background. For example, individuals of Ashkenazi Jewish descent have a 1 in 117 chance to be a carrier for type IIIB. There is also a type IIID that is not included in the test we offer.
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Revised November 2023
