General information: The SALSA MLPA Probemixes P191 Alport-mix 1 and P192 Alport-mix 2 are research use only (RUO) assays for the detection of deletions or duplications in the COL4A5 gene, which is associated with X-linked Alport syndrome (XLAS), also known as hereditary nephritis.

Alport syndrome (AS) is characterised by progressive loss of kidney function. The kidneys become less able to function as this condition progresses, resulting in end-stage renal disease (ESRD). Clinical features include haematuria, proteinuria and hypertension, while other symptoms such as sensorineural hearing loss and eye abnormalities may occur as well. Approximately two thirds of AS is X-linked. XLAS is caused by pathogenic variants in the COL4A5 gene located at Xq22.3. COL4A5 encodes one of the six subunits of type IV collagen. Approximately 10-15% of cases of XLAS are caused by deletions/duplications in COL4A5.

The first exon of COL4A5 is located very close to the first exon of the COL4A6 gene which encodes one of the other type IV collagen subunits. The two genes are arranged head-to-head and share a common promoter region. Deletions in the COL4A5 gene that extend into the COL4A6 gene result in diffuse leiomyomatosis accompanying the Alport syndrome (Nozu et al. 2017).

More information is available at https://www.ncbi.nlm.nih.gov/books/NBK1207/

Probemix content: The SALSA MLPA Probemix P191-B4 Alport-mix 1 contains 37 MLPA probes with amplification products between 130 and 490 nucleotides (nt). This includes 26 probes for the COL4A5 gene and one probe for the COL4A6 gene. In addition, ten reference probes are included that detect locations on the X-chromosome. The SALSA MLPA Probemix P192-B4 Alport-mix 2 contains 37 MLPA probes with amplification products between 130 and 444 nt. This includes 25 probes for the COL4A5 gene and two probes for the COL4A6 gene. In addition, ten 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.