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mucopolysaccharidosis type IIIB

What is Mucopolysaccharidosis Type IIIB?

Mucopolysaccharidosis type III B (MPS IIIB) also known as Sanfilippo syndrome type B, is a progressive lysosomal storage disorder. The features of MPS IIIB are due to the build up of glycosaminoglycans (GAGs), important complex carbohydrates responsible for many regulatory functions in the body. This build up primarily affects the central nervous system. Severity of the disease can range from mild to severe, even among affected individuals in the same family.

Infants with MPS IIIB appear normal at birth. The onset of symptoms including developmental delay and speech delay usually occurs between one to four years of age. Behavioral issues, such as aggressiveness and hyperactivity, typically develop in early childhood, often between ages of three and six years. Intellectual disability becomes more severe during this time period. Motor problems, such as difficulty swallowing and spasticity (stiff or rigid muscles), will also develop. The physical features of the disease, such as coarse facial features, skeletal abnormalities, and macrocephaly (large head) are often mild.

How common is Mucopolysaccharidosis Type IIIB?

The incidence of MPS IIIB varies significantly by region. Where estimates have been made, the occurrence ranges from 1 in 125,000 and 1 in 5,000,000 with an average incidence of approximately 1 in 374,000.

How is Mucopolysaccharidosis Type IIIB treated?

There is currently no approved treatment or cure for MPS IIIB.

What is the prognosis for a person with Mucopolysaccharidosis Type IIIB?

MPS IIIB is a condition with chronic issues and limited treatment options. Death typically occurs in the second or third decade of life, though survival into the fourth decade has been reported.