Mucopolysaccharidosis Type IIIA (SGSH)
Mucopolysaccharidosis type IIIA, also known as Sanfilippo syndrome type A, is a pan-ethnic, autosomal recessive disease caused by pathogenic variants in the gene SGSH. This disease is characterized by severe behavioral disturbances, including hyperactivity, sleep disturbances and destructive behavior. The age of onset is usually around 3 to 4 years of age. Other features include intellectual disability, enlarged liver and spleen, stiffness of the joints, hearing loss and seizures. No treatment is known. Life expectancy is generally reported to be into adolescence or early adulthood, but may be variable. Several specific variants have been associated with the development of either a more severe or a milder form of the disease, but many variants do not have a known genotype-phenotype correlation.
For information about carrier frequency and residual risk, please see the residual risk table.