Maroteaux-Lamy Syndrome

Maroteaux-Lamy Syndrome (also known as Mucopolysaccharidosis type VI)

Affecting one in 100,000 people, Maroteaux-Lamy syndrome is a rare genetic disorder where the enzyme (arylsulfatase B), which normally breaks down the mucopolysaccharides dermatan sulfate, is missing.  These mucopolysaccharides build up in all tissues in the body causing progressive deterioration and eventual death.  The disease was first described in 1963 in France by Dr. Maroteaux and Dr. Lamy.

Maroteaux-Lamy syndrome babies develop normally during the first two years, but as the mucopolysaccharides start to build up, the symptoms begin to appear in the third year of life.  The major features of this disease are skeletal and cardiac problems.  Unlike many of the other forms of mucopolysaccharidosis, Maroteaux-Lamy children do not experience any mental retardation; most patients have a normal intelligence.  Physical manifestations of the disease include coarse-featured faces, thick nostrils and lips, dwarfism, and claw hand deformities.  Patients also have vision problems (due to clouded corneas), and severe heart problems (as the coronary artery narrows and the heart valves thicken).  Other symptoms may include carpal tunnel syndrome, curvature of the spine, frequent runny nose, groin hernias, and hearing loss.  Most patients die between age ten and twenty-five of heart failure.

Because Maroteaux-Lamy syndrome is genetic, it is difficult to cure. Current approaches to Maroteaux-Lamy include genetic counseling for parents who are carriers of the disease, and improvements in early detection of the disease in unborn children (Maroteaux-Lamy can be detected with amniocentesis early in the second trimester).

For Maroteaux-Lamy patients, a variety of treatments have been tried.  The goal of treatment is to get the missing enzyme into the body. Unfortunately, directly injecting arylsulfatase B into the bloodstream has proven unsuccessful, since the enzyme cannot make it from there to the brain.  Injecting arylsulfatase B directly into the brain has not worked either, because not enough of the enzyme is absorbed.

To introduce arylsulfatase B into the body, both gene therapy and BMT are being used in clinical trials.  In gene therapy, researchers use a virus to place the gene that produces arylsulfatase B into the patient’s cells.  BMT is used to replace in the body bone marrow cells with the correct gene.  These marrow cells are able to travel to the brain much easier.  BMT is still an experimental treatment, but post-transplant patients do not suffer cardiac deterioration, and the accumulated mucopolysaccharides in the liver, lungs, and marrow slowly disappears.  Vision and hearing generally improve post-transplant, as well.  Further surgery is required to correct the skeletal problems (carpal tunnel surgery, for example).