Mucopolysaccharidosis Type VI

Mucopolysaccharidosis type VI (MPS VI) is a genetic condition that causes progressive storage in the organs of the body. Genetic changes, also called mutations, in the ARSB gene cause the deficiency or absence of an enzyme called arylsulfatase B. The arylsulfatase B enzyme is required to breakdown substances called glycosaminoglycans (GAGs). If this enzyme activity is too low or absent, the GAGs are not broken down correctly and they become stored in the lysosomes of the cells. Lysosomes are full of enzymes (such as arylsulfatase A) and are responsible for breaking material down in the cells for reuse or disposal. As the lysosomal storage builds over time, the cells become engorged until they can no longer work properly. This then leads to tissue and organ damage, and the symptoms of MPS VI. The main health problems in MPS VI are skeletal problems such as joint stiffness, joint pain, and limited range of motion. These are caused by abnormally shaped bones. People with MPS VI can also have heart problems, frequent respiratory infections, sleep apnea (when breathing pauses or is very shallow during sleep), vision loss from glaucoma or cloudy corneas, hearing loss, and enlargement of the liver and spleen. Cognitive impairment is not usually seen in MPS VI patients.