Shaily Saraf1, Priyanka Srivastava2, Inusha Panigrahi2, Venu Seenappa3, Rakesh Kumar4, Jaivinder Yadav4, Roshan Daniel2, Devi Dayal5. 1. Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India. 2. Genetic Metabolic Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India. 3. Molecular Genetics, Life Cell International, Chennai, Tamil Nadu, India. 4. Endocrinology and Diabetes Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, 160012, Chandigarh, India. 5. Endocrinology and Diabetes Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, 160012, Chandigarh, India. drdevidayal@gmail.com.
Abstract
OBJECTIVE: To characterize the CYP21A2 gene mutations in children with classic congenital adrenal hyperplasia (CAH). METHODS: A prospective, cross-sectional study was conducted on 24 children with classic CAH. Molecular characterization of the CYP21A2 gene was carried out by Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), or clinical exome sequencing. Another 21 previously mutation-proven CAH patients were also included and a combined result was drawn. RESULTS: Out of 45 children, pathogenic variants in the CYP21A2 gene were identified in 43 patients (95.5%). Homozygous, probable compound heterozygous, and heterozygous variants were seen in 69%, 22%, and 18% of patients, respectively. The most common variant was c.293-13C/A>G (33%), followed by deletion/duplication (24%), and c.955C>T (p.Gln319Ter) (21%), similar to previous Indian studies. Allelic frequencies of c.332_339del and c.518 T>A (p.Ile173Asn) were 9% and 4%, respectively. Less common variants were c.923dupT (p.Leu308PhefsTer6), c.92C>T (p.Pro31Leu), c.1069C>T (p.Arg357Trp), c.1267G>C (p.Gly423Arg), and c.710_719delins (p.Ile237_Met240delinsAsnGluGluLys). A good genotype-phenotype correlation was observed; only p.Pro31Leu and p.Ile173Asn variants showed discordance. The diagnostic yield of Sanger sequencing alone, Sanger sequencing with MLPA, and clinical exome alone was 85%, 100%, and 100%, respectively. CONCLUSIONS: All children, except two, diagnosed clinically as classic CAH, showed pathogenic variants in the CYP21A2 gene; the most common variant was c.293-13 C/A>G. The results suggest a broad mutation spectrum in the authors' single-center cohort of children with CAH. Clinical exome sequencing is the preferred stand-alone method for molecular diagnosis of CAH.
OBJECTIVE: To characterize the CYP21A2 gene mutations in children with classic congenital adrenal hyperplasia (CAH). METHODS: A prospective, cross-sectional study was conducted on 24 children with classic CAH. Molecular characterization of the CYP21A2 gene was carried out by Sanger sequencing, multiplex ligation-dependent probe amplification (MLPA), or clinical exome sequencing. Another 21 previously mutation-proven CAH patients were also included and a combined result was drawn. RESULTS: Out of 45 children, pathogenic variants in the CYP21A2 gene were identified in 43 patients (95.5%). Homozygous, probable compound heterozygous, and heterozygous variants were seen in 69%, 22%, and 18% of patients, respectively. The most common variant was c.293-13C/A>G (33%), followed by deletion/duplication (24%), and c.955C>T (p.Gln319Ter) (21%), similar to previous Indian studies. Allelic frequencies of c.332_339del and c.518 T>A (p.Ile173Asn) were 9% and 4%, respectively. Less common variants were c.923dupT (p.Leu308PhefsTer6), c.92C>T (p.Pro31Leu), c.1069C>T (p.Arg357Trp), c.1267G>C (p.Gly423Arg), and c.710_719delins (p.Ile237_Met240delinsAsnGluGluLys). A good genotype-phenotype correlation was observed; only p.Pro31Leu and p.Ile173Asn variants showed discordance. The diagnostic yield of Sanger sequencing alone, Sanger sequencing with MLPA, and clinical exome alone was 85%, 100%, and 100%, respectively. CONCLUSIONS: All children, except two, diagnosed clinically as classic CAH, showed pathogenic variants in the CYP21A2 gene; the most common variant was c.293-13 C/A>G. The results suggest a broad mutation spectrum in the authors' single-center cohort of children with CAH. Clinical exome sequencing is the preferred stand-alone method for molecular diagnosis of CAH.