Is Hunter syndrome hereditary?

Hunter syndrome is a hereditary genetic condition caused by a mutation in the IDS gene. It follows an X-linked recessive inheritance pattern, meaning it primarily affects males and is passed from mothers to their children.

Is Hunter syndrome hereditary?

Yes, Hunter syndrome (Mucopolysaccharidosis type II) is a hereditary condition. It is caused by a deficiency in the enzyme iduronate-2-sulfatase, which is necessary for breaking down complex sugars. Because the IDS gene is located on the X chromosome, the inheritance of Hunter syndrome is X-linked recessive. This means that females who carry the mutation on one of their X chromosomes are typically asymptomatic carriers, while males who inherit the mutation will manifest the disease.

What is the risk for children of an affected parent?

If a mother is a carrier of the Hunter syndrome mutation, each son has a 50% chance of inheriting the condition, and each daughter has a 50% chance of being a carrier. Because males with Hunter syndrome have only one X chromosome, they will pass the affected gene to all of their daughters (who will become carriers) and none of their sons, as sons receive the Y chromosome from their fathers.

Are de novo mutations common in Hunter syndrome?

While most cases of Hunter syndrome are inherited from a carrier mother, de novo (spontaneous) mutations do occur. Research indicates that approximately 20% to 30% of Hunter syndrome cases result from a new genetic mutation that occurs for the first time in the individual, rather than being passed down through generations.

How is genetic testing used for families?

Genetic testing is the gold standard for confirming a diagnosis of Hunter syndrome. Clinical geneticists recommend the following steps for families:

• Diagnostic testing: Sequencing the IDS gene to identify the specific mutation.


• Carrier testing: Offering molecular genetic testing to female relatives of a diagnosed individual to determine their carrier status.


• Prenatal diagnosis: Families may opt for chorionic villus sampling (CVS) or amniocentesis during pregnancy if a known mutation exists in the family.

Next steps

• Consult a clinical geneticist to discuss inheritance patterns and family planning.


• Connect with the 66 members of the Hunter syndrome community at DiseaseMaps.org to share experiences and find support.


• Request a referral for genetic counseling to understand carrier risks and reproductive options.

Medical disclaimer: This information is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Hunter Syndrome


• Orphanet: Mucopolysaccharidosis type II


• OMIM (Online Mendelian Inheritance in Man): IDURONATE-2-SULFATASE; IDS


• National MPS Society: Understanding Hunter Syndrome