General information
The SALSA MLPA Probemix P054 FOXL2-TWIST1 is a research use only (RUO) assay for the detection of deletions or duplications in the TWIST1, FOXL2, FOXC1, FOXC2, ATR, PITX2, PISRT1 and GPR143 (former OA1) genes, which are associated with ophthalmogenetic anomalies.

The protein encoded by the TWIST1 gene may affect the transcription of fibroblast growth factor receptors (FGFRs), a gene family implicated in craniosynostosis. It is suggested that TWIST1 proteins also regulate cytokine signalling. The TWIST1 gene is located on chromosome 7p21.1, contains two exons and spans only ~2.2 kb. Mutations in the TWIST1 gene are the major cause of Saethre-Chotzen syndrome (SCS; OMIM 101400). It has been estimated that 23% of SCS patients have a deletion of one copy of the TWIST1 gene. The majority of patients with a TWIST1 deletion are also developmentally delayed, presumably due to haploinsufficiency of nearby genes. The P054-C3 FOXL2-TWIST1 probemix contains two probes for the TWISTNB (POLR1F) gene, located at a distance of ~580 kb from TWIST1 in a relatively gene-poor region. There is no clear evidence yet, however, that a deletion of TWISTNB is the cause of the developmental delay. More information about SCS is available at https://www.ncbi.nlm.nih.gov/books/NBK1189/.

The FOXL2 gene encodes a forkhead transcription factor. Mutations in FOXL2 can cause blepharophimosis syndrome (BPES; OMIM 110100), an autosomal dominant syndrome characterised by eyelid malformation, sometimes associated with premature ovarian insufficiency (BPES type I), and sometimes not (BPES type II). The FOXL2 gene is located on chromosome 3q22.3 and consists of a single 2.7 kb exon. Several FOXL2 deletions have been identified. The deletions can span several Mb of chromosomal DNA and may extend to the ATR gene located 3.6 Mb telomeric of FOXL2 (D’haene et al. 2010). Three probes for ATR are included in this probemix. The non-protein-coding PISRT1 gene is located on 3q23 and consists of a single 0.5 kb exon. PISRT1 is located 0.3 Mb telomeric from FOXL2 and shares a common transcriptional regulatory region with FOXL2. More information about BPES is available at https://www.ncbi.nlm.nih.gov/books/NBK1441/.

Other genes detected by this probemix are PITX2 (4q25, Axenfeld-Rieger syndrome; OMIM 180500), GPR143 (Xp22.2; ocular albinism type I) and the forkhead transcription factors FOXC1 (6p25.3) and FOXC2 (16q24.1).

This SALSA MLPA probemix is not CE/FDA registered for use in diagnostic procedures. Purchase of this product includes a limited license for research purposes.

Probemix content
The SALSA MLPA Probemix P054-C3 FOXL2-TWIST1 contains 45 MLPA probes with amplification products between 130 and 490 nucleotides (nt). This includes six probes for the TWIST1 gene (three probes for exon 1, two probes for exon 2, and one probe for the upstream region of the gene), nine probes for the GPR143 (OA1) gene (one probe for each exon), two probes for the PITX2 gene, three probes for the ATR gene, five probes for the PISRT1 gene, three probes for the FOXL2 gene (all targeting exon 1), and two probes each for the FOXC1 and FOXC2 genes (all targeting exon 1 of the respective gene). In addition, ten reference probes are included that detect autosomal chromosomal locations. Complete probe sequences and the identity of the genes detected by the reference probes are available online (www.mrcholland.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.mrcholland.com.