US Kallmann syndrome meeting 2013. Notes taken. Part 1.

USA Patient Meeting 2013. Notes taken. Part 1.

Gender difference between males & females.

It used to be thought that there were about five times more cases of KS / CHH in males than in females. This has never been fully explained by genetics.

One school of thought is that there is actually no gender imbalance in reality. The disproportion in diagnosed cases might well be due to the lack of correct diagnosis of KS / CHH in females. It is not easy to correctly diagnose KS in females, especially if the oral contraceptive pill is used in treatment.

Un-published work done in Boston took the numbers of 600 patients in known KS / CHH families and came out with a ratio of 1 : 1.3 male to female cases.

Definition of a “rare disease”.

A rare disease is defined as one that is found in 1 in 2,000 of the general population. With KS / CHH being at around the 1 in 20,000 mark roughly it falls neatly in this category. About 8% of the general population of the USA could be classified as having a rare disease.

Start of puberty.

The age of onset of puberty has a range of 10 to 15 years in females with a mean of 12 years old. In males the range is 12 to 16 with a mean of 13 years old. Typically puberty takes 5 years to fully complete.

The age puberty starts in males is not easy to distinguish in boys whereas in girls it is marked by the first menstrual bleed.

2% of the population will show a constitutional delay of puberty. This group will start puberty naturally at some stage but early hormonal treatment might be given in appropriate cases.

Any delay of puberty by the age of 15 in females and 16 in males should be investigated by a reproductive endocrinologist or a paediatric endocrinologist.

Un-descended testes at birth.

Occurs in 2% of the male population but in up to 40% of boys with Kallmann syndrome.

GnRH and sexual differentiation.

Sexual differentiation into the male and female physical forms occurs in the first few weeks of life and is controlled by the hCG derived from the placenta. This is normally unaffected in people with KS / CHH so they are born physically male or female.

Normally there is a GnRH surge from the hypothalamus in the developing baby in the final trimester and into the first 6 months of life. This is a “mini-puberty” and can give rise to detectable levels of LH / FSH / testosterone or oestrogen. This mini-puberty is missing in patients with KS / CHH. This can be used as a diagnostic tool for babies where there is a likelihood of KS / CHH being passed on. This test is more sensitive in male infants than female infants.

The presence of micro-penis and un-descended testes at birth seen in some boys with KS / CHH is related to the lack of testosterone in boys in this mini-puberty.