A mucopolysaccharidosis (MPS) defect refers to a group of genetic disorders that occur when the body can't properly break down glycosaminoglycans (GAGs), also known as mucopolysaccharides. This breakdown issue is due to missing or malfunctioning enzymes.
Understanding Mucopolysaccharidoses (MPS)
MPS disorders are caused by a deficiency or malfunction of specific lysosomal enzymes needed to degrade GAGs. These enzymes are crucial for breaking down these complex sugar molecules, which are essential components of connective tissues. When these enzymes are faulty or absent, GAGs accumulate within cells, leading to various health problems.
The Root Cause: Enzyme Deficiency
The fundamental problem in MPS is the lack of proper enzyme function. As the reference states, MPS occurs when the enzymes needed to breakdown glycosaminoglycans are missing or don't work properly. People with MPS either don't produce enough of the necessary enzymes or produce enzymes that don't function correctly.
Consequences of GAG Accumulation
The buildup of GAGs in cells and tissues disrupts their normal function, resulting in a range of symptoms that can affect multiple organ systems.
Types of Mucopolysaccharidoses
There are several types of MPS, each caused by a deficiency in a different enzyme. Some common types include:
- MPS I (Hurler Syndrome, Scheie Syndrome, Hurler-Scheie Syndrome): Deficiency in the IDUA enzyme.
- MPS II (Hunter Syndrome): Deficiency in the IDS enzyme.
- MPS III (Sanfilippo Syndrome): Deficiencies in SGSH, NAGLU, HGSNAT, or GNS enzymes (four subtypes A-D).
- MPS IV (Morquio Syndrome): Deficiencies in GALNS or GLB1 enzymes (two subtypes A and B).
- MPS VI (Maroteaux-Lamy Syndrome): Deficiency in the ARSB enzyme.
- MPS VII (Sly Syndrome): Deficiency in the GUSB enzyme.
- MPS IX (Natowicz Syndrome): Deficiency in the HYAL1 enzyme.
Symptoms and Manifestations
The symptoms of MPS can vary widely depending on the specific type and severity of the disorder. Common symptoms include:
- Skeletal abnormalities
- Developmental delays
- Organ enlargement (e.g., liver, spleen)
- Heart problems
- Respiratory issues
- Coarse facial features
- Clouding of the cornea
Diagnosis and Treatment
Diagnosis typically involves enzyme assays to measure the levels of specific lysosomal enzymes. Genetic testing can also confirm the diagnosis.
Treatment options vary depending on the type of MPS and the severity of symptoms. They may include:
- Enzyme Replacement Therapy (ERT): Provides the missing enzyme intravenously.
- Hematopoietic Stem Cell Transplantation (HSCT): Replaces the patient's blood-forming cells with healthy donor cells.
- Supportive Care: Manages symptoms and complications.
