Maroteaux-Lamy Syndrome (MPS VI)

Background and History: 

Two French physicians, Drs. Pierre Maroteaux, a pediatrician, and Maurice Emile Joseph Lamy, a geneticist, first described this disorder in 1963.  It is one of a number of diseases resulting from a genetic mutation that causes a malfunction in an enzyme.  In this case, there is a defect in an enzyme important for the the breakdown of long chains of complex carbohydrates known as mucopolysaccharides.  For this reason it is considered to a member of disorders known as mucopolysaccharidoses (MPS).

Clinical Correlations: 

The accumulation of complex carbohydrates in tissues throughout the body is responsible for the widespread signs and symptoms found in this disease.  Growth is usually normal for the first several years followed by a slowing resulting in eventual shortness of stature.  The shortness of neck and trunk contribute to this.  The facial features tend to coarsen with age and the skull may appear large.  The liver and spleen are usually enlarged while involvement of the heart valves and the lungs often leads to respiratory difficulties and reduced physical stamina.  There is widespread bone disease and especially of the joints which become stiffened and limited in motion.  Hearing loss and even deafness are common.  The normally clear cornea (windshield of the eye) becomes cloudy after several years of age.  Intellect is usually normal although mild cognitive defects can be found in severe cases.  Involvement of the vertebrae may lead to neurologic problems. 

Genetics: 

This is an autosomal recessive disorder.  It requires a mutation in each of the two genes that code for an enzyme.  Parents of affected children are clinically normal but each carries one mutant copy and together they can transmit both mutations to their children.  About 25% of offspring can be expected to receive two copies of the mutation from carrier parents.

Diagnosis and Prognosis: 

There is no cure for MPS VI but the defective enzyme can be replaced which can lead to some improvement in symptoms.  In 2005, the FDA approved a commercial version of galsulfase known as Naglazyme® for the treatment of Maroteaux-Lamy syndrome.

Additional Information
Inheritance/Pedigree: 
Autosomal recessive