Sly syndrome
Sly syndrome, also called mucopolysaccharidosis type VII, is an autosomal recessive lysosomal storage disease caused by a deficiency of the enzyme β-glucuronidase. This enzyme is responsible for breaking down large sugar molecules called glycosaminoglycans. The inability to break down GAGs leads to a buildup in many tissues and organs of the body. The severity of the disease can vary widely.
Signs and symptoms
The most severe cases of Sly syndrome can result in hydrops fetalis, which results in fetal death or death soon after birth. Some people with Sly syndrome may begin to have symptoms in early childhood. Symptoms can include an enlarged head, fluid buildup in the brain, coarse facial features, enlarged tongue, enlarged liver, enlarged spleen, problems with the heart valves, and abdominal hernias. People with Sly syndrome may also have sleep apnea, frequent lung infections, and problems with vision secondary to cloudy corneas. Sly syndrome causes various musculoskeletal abnormalities that worsen with age. These can include short stature, joint deformities, dysostosis multiplex, spinal stenosis, and carpal tunnel syndrome.While some individuals have developmental delay, others may have normal intelligence. However, the accumulation of GAGs in the brain usually leads to the slowing of development from ages 1–3, and then a loss of previously learned skills until death.