Multiplex ligation-dependent probe amplification (MLPA) assay for the detection of CYP21A2 mutations in Egyptian children with congenital adrenal hyperplasia / Aisha Omar Mohamed Atef Tolba ; Supervised Fatma Ahmed Fathy Elmougy , Mona Fouad Hassan Hafez , Iman Atef Mandour

Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Clinical and Chemical Pathology

Background: Steroid 21-hydroxylase deficiency (21-OHD) is the most common cause of congenital adrenal hyperplasia (CAH). It is an autosomal recessive monogenic disorder caused by variations in CYP21A2 gene. It shows high prevalence in Egypt and not included in the national neonatal screening programs due to limited studies. Early accurate diagnosis for different genetic variations in the gene is important to reduce mortality and morbidity. Aim: To identify CYP21A2 common gene mutations and copy number using Multiplex Ligation-dependent Probe Amplification (MLPA) assay and their genotype-phenotype correlation among a group of Egyptian children with CAH. Methods: The CYP21A2 gene was screened using MLPA assay in 112 unrelated Egyptian children with 21-OHD CAH (33 males and 79 females). Results: Eight common genetic variants were identified I2G, large deletions, large gene conversion (LGC), I172N, F306+T, -113 SNP, 8bp Del and exon 6 cluster (V237E, M239K) with allelic frequency of 32.62%, 15.45%, 7.30%, 3.00%, 2.58%, 2.15%, 0.86% and 0.86%, respectively. Among large deletions, three types of chimeric genes (CH-1, CH-7, CAH-X CH-1) were present. One copy of CYP21A2 was found in 5 cases (4.5%), three copies were detected in 7 cases (6.3%) and one case (0.9%) harboring four copies. Conclusion: The MLPA assay is a rapid tool to detect copy number and different genetic variations that are common in CYP21A2 gene it can be tailored to ethnic group

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