Families

Mucopolysaccharidosis type VII (MPS VII), also known as Sly Syndrome, is a very rare and serious genetic disorder. It happens because of a change (mutation) in a gene called GUSB. This gene normally helps the body make an important enzyme called beta-glucuronidase. When this enzyme doesn’t work properly, certain substances, called glycosaminoglycans or GAGs, build up in the body’s cells and cause damage over time.

MPS VII is passed down in families in what's called an autosomal recessive way. This means that a child who presents the condition usually inherits the faulty gene from both parents.

This condition is extremely rare. Fewer than 1 in 1 million people are affected, and only about 200 people are known to have it worldwide.

MPS VII can appear in different ways. Some babies may show signs before or right after birth, such as severe swelling in the body (a condition called hydrops fetalis), yellowing of the skin (jaundice), an enlarged liver or spleen, or even stillbirth. In other cases, symptoms show up in early childhood and can include delays in development, learning problems, unusual facial features, bone and joint problems, and other health issues.