PCR assay using 22q11.2 highly polymorphic markers for exclusion of 22q microdeletion: Technical optimization and application in North Africa

22q11.2 deletion syndrome is a genomic disorder with a broader clinical and genetic spectrum. To exclude the presence of 22q11.2 microdeletion, we optimize a PCR-RFLP analysis of three SNP located in the typically proximal 22q11.21 deleted region of 1.5 Mb. PCR reactions, optimized with a Touch-Down program, were performed using three pairs of primers. The amplicons were cleaved by three restrictive enzymes: HaeIII, CviAII, and BsrI applied respectively, for rs4819523, rs4680, and rs5748411. The efficiency of this PCR RFLP assay was confirmed in the light of its application in a small cohort of 10 Tunisian patients, having a congenital heart defect and a known status of 22q11 deletion by FISH and MLPA. The principle of the proximal 22q11.2 microdeletion, applied with exclusion technique seems to be interesting but further population studies for the determination of the heterozygosity rate of the polymorphic 22q11 region markers are needed, particularly in North Africa.