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Genetics of Kallmann Syndrome / HH

December 10, 2011

This above picture was produced by Prof. Nelly Pitteloud at the University of Lausanne in Switzerland, one of the leading centres into research into KS / HH. It shows the 11 gene defects so far that have been shown to cause cases of Kallmann syndrome or Hypogonadotrophic Hypogonadism.

Some key points from this diagram:

  • Even though 11 different gene defects have been identified by 2011 there remains 68% of cases with an unknown genetic cause.


  • KS / HH now thought to be caused in some cases by two of these gene defects working in combination. This brings up the possibility of the one gene defects being passed down the generations and not causing too many problems, but when added to a second of these gene defects it causes a case of KS / HH.


  • The KAL-1 gene defect which causes the “classic” x-linked Kallmann syndrome accounts for only 5% of overall cases. The fact that x-linked KS is the most widely studied condition is probably due to the fact it is accompanied by a clear set of additional symptoms not normally seen in other cases of KS or HH.


  • The fact that so many cases of KS / HH still have an unknown genetic cause means that genetic screening and predicting the chances of passing on the condition very difficult if next to impossible, unless there is a strong family history.






  1. How is HH connected with KS?

    • HH (hypogonadotrophic hypogonadism) and Kallmann syndrome are essentially the same condition, the only difference being Kallmann syndrome has the additional symptom of a lack of sense of smell.

      About 50% of HH cases can be classed as Kallmann syndrome.

      The diagnosis & treatment for KS & HH are the same. It is just with KS you might notice the symptom of a lack of sense of smell before the age puberty is due.

  2. shababawi permalink

    I was diagnosed with Kallman Syndrome since I was 17. I am 28 yeard old now, married. I have been on testesterone therapy (Sustanon) 250 mg once every three weeks. I have started taking HCG injection to start simulating the production of testesterone before taking another injection to stimulate the sperm production for the purpose of having children! hopefully 🙂 Just liked to share my story !

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