Mucopolysaccharidosis Type IIIC (HGSNAT)
Mucopolysaccharidosis type IIIC, also known as Sanfilippo syndrome type C, is a pan-ethnic, autosomal recessive disease caused by pathogenic variants in the gene HGSNAT. 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 approximately 34 years of age, but may be variable. No clear genotype-phenotype correlation is known.
For information about carrier frequency and residual risk, please see the residual risk table.