Mucopolysaccharidosis

Mucopolysaccharidosis (MPS) is a group of rare genetic disorders caused by the deficiency of enzymes needed to break down and recycle sugar molecules within cells. These sugar molecules, known as glycosaminoglycans (GAGs), are essential components of connective tissue and play critical roles in various bodily functions.

Causes and Inheritance

MPS is inherited in an autosomal recessive pattern, meaning that a child must inherit one defective gene from each parent to develop the condition. The genes responsible for MPS encode enzymes involved in the degradation of GAGs. When these enzymes are deficient or absent, GAGs accumulate within cells, leading to cellular dysfunction and tissue damage.

Types of Mucopolysaccharidosis

There are several types of MPS, each resulting from the deficiency of a specific enzyme:

• MPS I (Hurler syndrome): caused by a deficiency of alpha-L-iduronidase enzyme.
• MPS II (Hunter syndrome): caused by a deficiency of iduronate-2-sulfatase enzyme.
• MPS III (Sanfilippo syndrome): caused by a deficiency of one of four enzymes involved in the breakdown of heparan sulfate.
• MPS IV (Morquio syndrome): caused by a deficiency of either N-acetylgalactosamine-6-sulfatase or beta-galactosidase enzyme.
• MPS VI (Maroteaux-Lamy syndrome): caused by a deficiency of N-acetylgalactosamine-4-sulfatase enzyme.
• MPS VII (Sly syndrome): caused by a deficiency of beta-glucuronidase enzyme.

Symptoms and Diagnosis

The symptoms of MPS can vary depending on the type and severity of the condition. Common features include:

• Coarse facial features
• Cloudy corneas
• Short stature
• Joint stiffness and limited mobility
• Hearing loss
• Respiratory problems
• Cardiac issues

Diagnosis of MPS typically involves a combination of clinical evaluation, laboratory tests (such as enzyme assays and genetic analysis), and imaging studies.

Treatment and Management

Treatment for MPS aims to manage symptoms, slow disease progression, and improve quality of life. Available therapies include:

• Enzyme replacement therapy (ERT) to replace the deficient enzyme
• Hematopoietic stem cell transplantation to provide a source of healthy cells
• Surgery to address specific issues, such as joint problems or spinal cord compression
• Supportive care, including physical therapy, occupational therapy, and speech therapy

While these treatments can help alleviate symptoms and improve outcomes, there is currently no cure for MPS.