Who is affected by GnRH deficiency (Including Kallman syndrome)?

Yes. All forms of GnRH deficiency (including Kallmann syndrome) are seen in both men and women, even though it is more common in men. Major international centres typically report having around 3-times as many men as women attending their service. If this is a genuine reflection of disease prevalence among men and women, we remain unable to explain it in terms of our current knowledge of the genetics. However, it may be that this observation reflects "ascertainment bias", with many affected women seeing a gynaecologist and just getting prescribed the contraceptive pill to give them regular periods. These women may never get an exact diagnosis and/or never get referred in to a major treatment centre for GnRH deficiency.

GnRH deficiency is a very rare condition that may be under reported so an accurate prevalence may be difficult to establish. Our best estimate of the prevalence in men comes from a 1970 study of 40,000 young French conscripts, that gave a figure of 1-in-4,000.

GnRH deficient conditions can be hereditary and can be passed down through the generations.

Even though research is ongoing, there is much still to be understood about the genetic mechanisms of GnRH deficiency. Given the current level of knowledge of the genetics of GnRH deficiency it is very difficult for clinicians to be able to give prospective parents a reliable, accurate prediction on the chances of their offspring being born with a GnRH deficient condition.

Unlike other genetic conditions, where the genetic cause is known and can be tested for, the exact cause for most GnRH deficiency cases is unknown. This, coupled with the fact that some GnRH conditions are can be caused by two separate gene mutations working together, makes any prediction of the chances of passing the condition on very difficult. Additional research necessary to elucidate the genetic basis of GnRH deficiency.