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What Causes You To Have Hunter Syndrome & Who Is At Risk?

Hunter syndrome is an X-linked recessive disorder. It is a rare type of genetic disorder.

What Causes You To Have Hunter Syndrome?

Hunter syndrome is caused when a mother passes a defective chromosome to her child. Thus, hunter syndrome is an X-linked syndrome.(1)

The defective chromosome leads to some problems with an enzyme, which is responsible for the breaking up of some complex molecules. The defective chromosome makes the enzyme malfunctioning or completely absent. This enzyme is called enzyme iduronate 2-sulfatase. If this enzyme does not function as it should or is not present at all, it leads to a harmful build up of those complex molecules in the blood, cells and connective tissues in the body. This collection can cause some serious progressive and permanent damage to the body. There may be defects in appearance, organ function, mental and physical growth and development.(2)

Who Is At Risk?

Family History– Hunter syndrome results due to the transfer of the defective chromosome from a mother to her child. The mother must carry the defective X chromosome in order to pass it to her child. However, she herself is unaware that she carries such a chromosome in her body, and she isn’t affected by this disorder. Hence, Hunter syndrome is an X-linked recessive disorder.(3)

Gender– Hunter syndrome is very commonly seen in males. Girls are at a very low risk of developing this disorder. This is because girls carry two x chromosomes. If one of them is defective, the other one can compensate for the defective chromosome by giving a functioning and normal gene. However, boys carry one x and one y chromosome, which means that if they inherit a defective x chromosome, there is not another one to compensate for the defective one. Hence, Hunter syndrome usually always is seen in males.

Complications Of Hunter Syndrome

According to the type and severity of the hunter syndrome, different types of complications can occur in a child-

Complications In The Respiratory System-

  • A thick tongue, thickening of gums and nasal passages can lead to extreme difficulty in breathing
  • Children with hunter syndrome usually have an ongoing sinus or ear infection, pneumonia and other respiratory infections
  • Sleep apnea can be seen in many children with hunter syndrome

Complications In The Cardiovascular System-

  • Thickening of heart valves can lead to their improper closure
  • This results in a compromised blood supply to different parts of the body
  • With the gradual progress of the disease, the heart complications progress as well and eventually may lead to heart failure
  • The thickening of arteries may also lead to an abnormally high blood pressure, which can turn out to be extremely fatal

Complications On The Skeletal System-

  • The collection of the complex molecules in the connective tissue leads to bone and joint abnormalities
  • This affects the growth of the child, can be painful and causes deformities in bones. This can compromise his ability to move around
  • The child can experience stiffness in joints, which can be extremely painful
  • The bone abnormalities may make the child extremely short heighted
  • Those having hunter syndrome also suffer from hernias, due to enlargement of internal organs

Complications In The Nervous System-

  • Varied neurological complications are present in a child with hunter syndrome. These are progressive in nature
  • There can be severe headaches, vision problems and mental instability to your child
  • Compression of various nerves due to bone deformities can lead to other complications like carpal tunnel syndrome

Children with hunter syndrome also take a long time to recover from usual childhood illnesses. Hence, it is recommended to take precautions and preventive measures already.

A defective X-chromosome leads to a malfunctioning or absence of a certain enzyme which is responsible for the break down of certain complex molecules. When this break down does not happen correctly, it leads to a rare genetic disorder called hunter syndrome.


  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3249184/
  2. https://medlineplus.gov/ency/article/001203.htm
  3. https://www.mayoclinic.org/diseases-conditions/hunter-syndrome/symptoms-causes/syc-20350706

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:April 19, 2019

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