CytoCell Kallmann (KAL1)/STS Probe Combination

Probe specification

• KAL1, Xp22.31, Red
• STS, Xp22.31, Green
• DXZ1, Xp11.1-q11.1, Green

The KAL1 probe is 334kb, labelled in red and covers the entire KAL1 gene and the DXS278 and DXS7053 markers. The STS probe is 282kb, labelled in green and covers the STS gene and most of the HDHD1A and STS genes. The probe mix also contains a control probe for the X centromere (DXZ1), labelled in green.

Probe information

Kallmann syndrome (KS) is a developmental disease characterised by olfactory deficiency³ and hypogonadotrophic hypogonadism (HH), which is responsible for the absence of spontaneous puberty¹.

Kallmann syndrome is a heterogeneous developmental genetic disorder affecting approximately 1 in 8,000 males and 1 in 40,000 females². Reports indicate three modes of inheritance: X-linked, autosomal dominant and autosomal recessive^1,4.

It has been shown that mutations in the KAL1 gene on Xp22.3 result in the X-linked form of KS⁵. KAL1 consists of 14 exons and extends over 200kb and abnormalities of KAL1 reported in patients with KS include missense and nonsense mutations, splice site mutations, intragenic deletions and submicroscopic chromosomal deletions involving the entire KAL1 gene⁷.

Steroid Sulphatase Deficiency (STS) (also known as X-linked Ichthyosis)⁸ is the second most common type of ichthyosis and one of the most frequent human enzyme deficiency disorders.

Deficiency of the STS enzyme is known to be responsible for dark, adhesive and regular scaling of the skin⁹. The gene encoding this protein maps to the distal short arm of chromosome X, which escapes X-chromosome inactivation and has the highest ratio of chromosomal deletions among all genetic disorders¹⁰. Complete deletions of the STS gene have been found in more than 90% of patients¹¹. The deletions can extend to involve neighbouring genes, causing contiguous gene defects. Therefore, STS may be associated with KS¹².