Defisiensi Enzim: Sindrom Hunter

Summary

Hunter Syndrome, or Mucopolysaccharidosis type II, is a rare genetic disorder caused by a deficiency in the enzyme iduronate-2-sulfatase (I2S), leading to the accumulation of sugar molecules in cells. This condition primarily affects males and impacts various organs and tissues, causing physical and mental developmental delays. Early symptoms include facial changes, enlarged organs, and hearing or vision problems. Diagnosis involves urine, blood, and genetic testing, while treatment options such as enzyme replacement therapy and bone marrow transplant can help manage symptoms, although they do not cure the disease. Early intervention is crucial for improving quality of life.

Takeaways

• 😀 Hunter Syndrome (Mucopolysaccharidosis Type II) is a rare genetic disorder that affects multiple organs due to a deficiency in the enzyme iduronate 2-sulfatase (I2S).
• 😀 The disorder primarily affects males because it is linked to the X chromosome.
• 😀 Hunter Syndrome leads to the accumulation of glycosaminoglycans (GAGs), causing progressive damage to tissues and organs, especially in the liver, heart, and brain.
• 😀 Symptoms of Hunter Syndrome usually begin to appear between the ages of 2 to 4, including enlarged cheeks, wide nose, and macroglossia (enlarged tongue).
• 😀 The condition can cause physical and mental developmental delays, as well as hearing loss, vision issues, and heart valve problems.
• 😀 Hunter Syndrome is diagnosed through a combination of urine tests for elevated GAGs, blood enzyme tests showing low or absent I2S activity, and genetic testing to confirm mutations in the IDS gene.
• 😀 Early diagnosis is critical for managing the disease and slowing its progression, though there is no cure for the disorder.
• 😀 Enzyme replacement therapy (ERT), using synthetic I2S enzyme, can slow the disease's progression, though its effectiveness is still being studied.
• 😀 Bone marrow transplantation (BMT) may be an option for patients with milder forms of the disease, potentially improving organ function and mobility, though it does not address vision or bone issues.
• 😀 The prognosis for individuals with Hunter Syndrome varies, but early intervention can help improve quality of life and extend survival.
• 😀 Ongoing research into gene therapy and other treatments aims to improve outcomes for people with Hunter Syndrome in the future.

Q & A

What is Hunter Syndrome?

Hunter Syndrome, also known as Mucopolysaccharidosis Type 2, is a rare genetic disorder caused by a metabolic dysfunction due to a lysosomal enzyme deficiency. This condition affects various parts of the body and is most common in males due to its linkage to the X chromosome.

What causes Hunter Syndrome?

Hunter Syndrome is caused by a deficiency in the enzyme Iduronate-2-sulfatase (I2S), which is necessary for breaking down large sugar molecules called glycosaminoglycans (GAGs). A mutation in the IDS gene results in this enzyme deficiency, leading to the accumulation of GAGs in the body, causing damage to tissues and organs.

How does the deficiency of the I2S enzyme affect the body?

The deficiency of I2S enzyme leads to the buildup of GAGs in cells, especially in lysosomes, which causes these cells to swell. This accumulation results in the enlargement of tissues and organs, and over time, it causes organ damage and impacts physical and mental development.

Which enzyme is deficient in individuals with Hunter Syndrome?

The enzyme that is deficient in individuals with Hunter Syndrome is Iduronate-2-sulfatase (I2S).

At what age do the symptoms of Hunter Syndrome typically appear?

Symptoms of Hunter Syndrome generally begin to appear between the ages of 2 and 4 years, with physical characteristics such as enlarged cheeks, a wider nose, and macroglossia (enlarged tongue).

What are the common physical features seen in children with Hunter Syndrome?

Common physical features of Hunter Syndrome include large and rounded cheeks, a broad nose, macroglossia (enlarged tongue), enlarged head (macrocephaly), hydrocephalus (fluid buildup in the brain), hepatosplenomegaly (enlarged liver and spleen), and hernia.

How is Hunter Syndrome diagnosed?

Hunter Syndrome is diagnosed through urine tests (for high levels of GAGs), blood tests (to check for low or absent enzyme activity), and genetic testing (to identify mutations in the IDS gene). A clinical diagnosis based on physical signs and family medical history is often the first step.

What are the available treatment options for Hunter Syndrome?

Treatment options for Hunter Syndrome include enzyme replacement therapy (ERT) using synthetic I2S enzyme, which helps slow the progression of symptoms, and bone marrow transplantation in milder cases, which can provide a new source of the enzyme. However, these treatments do not cure the disease and have varying levels of effectiveness.

What is enzyme replacement therapy (ERT) for Hunter Syndrome?

Enzyme replacement therapy (ERT) involves the intravenous infusion of synthetic Iduronate-2-sulfatase (I2S) to replace the deficient enzyme in individuals with Hunter Syndrome. This therapy can help slow down or prevent the progression of some symptoms, especially if started early, but it is a very costly treatment.

What are the challenges associated with treating Hunter Syndrome?

Challenges in treating Hunter Syndrome include the high cost of enzyme replacement therapy, which can exceed $375,000 annually, and the fact that treatments do not fully address all symptoms, such as vision or bone-related problems. The benefits of these therapies, especially in terms of improving quality of life, remain unclear.