Pitfalls in molecular diagnosis of 21-hydroxylase deficiency in congenital adrenal hyperplasia

Genotype of congenital adrenal hyperplasia patients with testicular adrenal rest tumor

“…Molecular genetic analysis of CYP21A2 was performed either by targeted analysis through screening of the most common CYP21A2 pathogenic variants or sequencing the entire coding region and exon-intron boundaries of CYP21A2. In this multicenter study, various molecular methodologies including allele specific polymerase chain reaction (PCR), reverse dot-blot method, PCR-RFLP, and reversehybridization strip-based assay were used to screen common pathogenic variants as previously described (Németh et al, 2012;Kolahdouz et al, 2015;Özyılmaz et al, 2018). Most of the inactivating mutations or deletions are generated by gene conversion or unequal crossing over between the functional (CYP21A2) gene and a highly homologous nonfunctional pseudogene CYP21A1P (Kolahdouz et al, 2015).…”

“…In this multicenter study, various molecular methodologies including allele specific polymerase chain reaction (PCR), reverse dot-blot method, PCR-RFLP, and reversehybridization strip-based assay were used to screen common pathogenic variants as previously described (Németh et al, 2012;Kolahdouz et al, 2015;Özyılmaz et al, 2018). Most of the inactivating mutations or deletions are generated by gene conversion or unequal crossing over between the functional (CYP21A2) gene and a highly homologous nonfunctional pseudogene CYP21A1P (Kolahdouz et al, 2015). Pseudogene derived common pathogenic variants (c.92C>T; p. P31L, c.293-13C>G (formerly known as: In2G, IVS2-13C>G), c.332_339del-GAGACTAC; p. Gly111Valfs*21, c.518T>A; p. Ile173Asn, Exon 6 cluster (c. 710T>A; p. Ile237Asn, c.713T> A; p. Val238Glu, c.719T>A; p. Met240Lys), c.844G> T; p. Val282Leu, c.923dupT; p. Leu308PhefsTer6, c.955C >T; p. Gln319Ter, c.1069C>T; p. Arg357Trp and c.1360C>T; p. Pro454Ser) account for approximately 90-95% point mutations (Krone and Arlt, 2009;Narasimhan and Khattab, 2019).…”