General information: The SALSA MLPA Probemix P160 STS is a research use only (RUO) assay for the detection of deletions or duplications in the STS gene, which is associated with X-linked ichthyosis. This probemix can also be used to detect STS deletions or duplications that extend into the neighbouring ANOS1 (KAL1) and NLGN4X genes.

X-linked ichthyosis is a skin disorder characterised by dark brown and black, polygonal scales particularly found on the trunk, neck and extremities, which are caused by a deficiency of the steroid sulfatase (STS) enzyme. Placental steroid sulfatase deficiency occurs in pregnant mothers of affected males and is associated with low oestrogen production, failed induction of and prolonged labour. In up to 90% of patients, X-linked ichthyosis is caused by complete deletion of the STS gene located on chromosome Xp22.31 (Hernández‐Martín et al. 1999), but partial STS gene deletions and point mutations have also been described.

Larger deletions at Xp22.31 might include neighbouring genes such as ANOS1 or NLGN4X. Loss of the ANOS1 gene causes 5-10% of Kallmann syndrome, which is characterised by impaired sense of smell (anosmia/hyposmia) and delayed or absent puberty due to hypogonadotropic hypogonadism. Copy number variations and mutations in the NLGN4X gene have been associated with X-linked mental retardation and autism.

Probemix content: The SALSA MLPA Probemix P160-C1 STS contains 35 MLPA probes with amplification products between 130 and 427 nucleotides (nt). This includes 13 probes for the STS gene, one probe for each exon with the exception of exon 3, as well as two flanking probes targeting the PUDP gene. Furthermore, three probes for the ANOS1 gene and one flanking probe for the GPR143 gene, as well as five probes for the NLGN4X gene are included. In addition, 11 reference probes are included that detect locations on the X-chromosome. Complete probe sequences and the identity of the genes detected by the reference probes are available online (www.mlpa.com).

This probemix contains nine quality control fragments generating amplification products between 64 and 105 nt: four DNA Quantity fragments (Q-fragments), two DNA Denaturation fragments (D-fragments), one Benchmark fragment, and one chromosome X and one chromosome Y-specific fragment. More information on how to interpret observations on these control fragments can be found in the MLPA General Protocol and online at www.mlpa.com.