Hunter syndrome is a rare, inherited genetic disorder. According to provided reference, it occurs when the body cannot properly break down (digest) certain sugar molecules. This inability to break down these molecules leads to a buildup in organs and tissues, causing damage that can affect both physical and mental development.
Understanding Hunter Syndrome
Hunter syndrome, also known as mucopolysaccharidosis type II (MPS II), is caused by a deficiency or absence of the enzyme iduronate-2-sulfatase (I2S). This enzyme is essential for breaking down complex sugar molecules called glycosaminoglycans (GAGs), previously known as mucopolysaccharides.
The Impact of GAG Buildup
The undigested GAGs accumulate within cells throughout the body. This buildup leads to a wide range of symptoms that can vary in severity. Some of the common areas affected include:
- Skeletal System: Joint stiffness, bone deformities, and short stature.
- Respiratory System: Frequent respiratory infections, obstructive airway disease.
- Cardiovascular System: Heart valve problems, enlarged heart.
- Central Nervous System: Developmental delays, intellectual disability (more common in severe forms).
- Other: Enlarged liver and spleen, coarse facial features, hearing loss.
Types of Hunter Syndrome
Hunter syndrome is generally classified into two main types:
- Severe Form: This is the more common and rapidly progressing form. It is characterized by significant cognitive impairment and a shorter life expectancy.
- Attenuated (Mild) Form: This form progresses more slowly, with milder symptoms and little to no cognitive impairment. Individuals with the attenuated form often live into adulthood.
Diagnosis and Treatment
Diagnosis typically involves enzyme assays to measure I2S activity and genetic testing to identify mutations in the IDS gene.
Current treatment options focus on managing symptoms and improving quality of life:
- Enzyme Replacement Therapy (ERT): This involves intravenous infusions of a synthetic version of the I2S enzyme. ERT can help reduce GAG storage in some tissues and organs but does not cross the blood-brain barrier effectively to address neurological symptoms.
- Hematopoietic Stem Cell Transplantation (HSCT): This procedure aims to replace the patient's defective cells with healthy stem cells that can produce the I2S enzyme. HSCT can be effective in slowing the progression of the disease, particularly in younger patients.
- Symptom Management: This includes treatments for specific symptoms such as respiratory infections, heart problems, and joint stiffness.
