The FANCB gene encodes a member of the Fanconi anemia complementation group B. This protein is assembled into a nucleoprotein complex that is involved in the repair of DNA lesions. Mutations in this gene can cause chromosome instability (
https://www.ncbi.nlm.nih.gov/gene/2187).
The FANCB gene (10 exons), spans ~29.7 kb of genomic DNA and is located on chromosome Xp22.2, ~14.8 Mb from the p telomere.
The P113-B1 probemix contains one probe for each exon of the FANCB gene, with one additional probe for exon 3, 8 and 10. Furthermore, two probes upstream of exon 1 and one probe downstream of exon 10 are included. In addition, 9 reference probes are included in this probemix, detecting several different locations on the X chromosome.
This SALSA
® MLPA
® probemix is designed to detect deletions/duplications of one or more sequences in the aforementioned gene in a DNA sample. Deletions of a probe’s recognition sequence on the X-chromosome will lead to a complete absence of the corresponding probe amplification product in males, whereas female heterozygotes are recognisable by a 35 50% reduction in relative peak height. Note that a mutation or polymorphism in the sequence detected by a probe can also cause a reduction in relative peak height, even when not located exactly on the ligation site! In addition, some probe signals are more sensitive to sample purity and small changes in experimental conditions. Therefore, deletions and duplications detected by MLPA should always be confirmed by other methods. Not all deletions and duplications detected by MLPA will be pathogenic; users should always verify the latest scientific literature when interpreting their findings. We have no information on what percentage of defects in this gene is caused by deletions/duplications of complete exons. Finally, note that most defects in this gene are expected to be small (point) mutations which will not be detected by this SALSA
® MLPA
® test.