Diagnostic Tests for Kallmann's Syndrome and Hypogonadotrophic Hypogonadism

Genetic Tests:

At present there is no easy, reliable test for Kallmann's syndrome or HH. There are at least 6 different genes on 5 different chromosomes that may play a part in the development of Kallmann's and HH. Unlike other genetic conditions there is at present no one target gene that can be screened for to give an early diagnosis of Kallmann's or HH.

There is a test available in certain places for the gene KAL-1. This gene is located on the x-chromosome and its lack of function is thought to be the prime cause of x-linked Kallmann's. In Kallmann's or HH the whole gene may be absent, or there might be a very small error within the gene. Testing for the complete absence of the gene is fairly straight forward, however screening for a small error within the gene is not so easy. 

It is also thought that KAL-1 interacts with other genes to cause other forms of Kallmann's and HH.

A doctor may order a karyotype test in order to rule out other genetic conditions.

A karyotype test is used to determine the genetic make up of the individual.

A normal male will have 46 chromosomes including one X and one Y chromosome, known as 46,XY

A normal female will have 46 chromosomes including two X chromosomes, known as 46,XX

There are genetic conditions where this pattern is altered which can lead to hypogonadal conditions with symptoms very similar to Kallmann's or HH.

A doctor will use the karyotype to help to identify a specific condition or to rule out other possibilities.

Kallmann's syndrome and hypergonadotrophic hypogonadism will show the normal 46,XY or 46,XX karyotypes.

There are conditions where the number of chromosomes present is different from expected. Most of these conditions are more common than Kallmann's and can produce symptoms which are very similar to Kallmann's or HH.

Examples include:

Klinefelter's Syndrome:   47,XXY. Male with extra X chromosome.

Turner's Syndrome:         45, XO. Female with one X chromosome absent.

XYY Syndrome:               47,XYY. Male with extra Y chromosome.

XX Man:                          46,XX. Normal female genotype but with physically male.

There are also 'mosaic' conditions where two different karyotypes can occur at the same time.