Rapid Second-Tier Molecular Genetic Analysis for Congenital Adrenal Hyperplasia Attributable to Steroid 21-Hydroxylase Deficiency

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 51; no. 2; pp. 298 - 304
• Main Authors: Kosel, Siegfried, Burggraf, Siegfried, Fingerhut, Ralph, Dorr, Helmut G, Roscher, Adelbert A, Olgemoller, Bernhard
• Format: Journal Article
• Language: English
• Published: Washington, DC Am Assoc Clin Chem 01.02.2005; American Association for Clinical Chemistry; Oxford University Press
• Subjects: 17-alpha-Hydroxyprogesterone - blood; Adrenal Hyperplasia, Congenital - enzymology; Adrenal Hyperplasia, Congenital - genetics; Analytical, structural and metabolic biochemistry; Autoanalysis; Biological and medical sciences; Birth weight; False Positive Reactions; Fundamental and applied biological sciences. Psychology; Genetic testing; Humans; Hyperplasia; Immunoassay; Infant, Newborn; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Mutation; Neonatal Screening - methods; Polymerase Chain Reaction; Prospective Studies; Sensitivity and Specificity; Steroid 21-Hydroxylase - genetics; Steroids; Endocrinopathy; Adrenal cortex diseases; Enzyme; Hyperadrenocorticism; Biochemistry; Enzymopathy; Congenital adrenal hyperplasia syndrome; Adrenal gland diseases; Clinical biology; Genetics; Oxidoreductases; Molecular biology; Steroid 21-monooxygenase
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1373/clinchem.2004.042416

Neonatal screening for steroid 21-hydroxylase (CYP21) deficiency is performed to identify congenital adrenal hyperplasia (CAH). The immunologic assay for 17alpha-hydroxyprogesterone (17-OHP) has a high rate of false positives. We assessed the potential for increasing the specificity for CAH by use of a second step involving analysis of the CYP21 gene. Between January 1999 and December 2003, a total of 810,000 newborns were screened. Of these, 7920 had to be retested because their 17-OHP values were above the cutoff of the assay. Sixty-one had positive 17-OHP values in their recall samples and were diagnosed as having CAH. We used a rapid assay for common mutations of the CYP21 gene to analyze these 61 samples. In a prospective study, 198 consecutive samples that had increased 17-OHP and 100 samples that had normal 17-OHP concentrations were genotyped. Fifty-nine of 61 cases diagnosed as having CAH were confirmed genetically as CYP21 deficiencies. One patient had a 3beta-hydroxysteroid dehydrogenase deficiency, and one patient carried no CYP21 mutations. The 198 increased 17-OHP results were designated as false positives after immunologic testing of recall samples. None of these samples exhibited the genetic pattern consistent with CYP21 deficiency. If samples with increased 17-OHP values were screened genetically, the number of retests would decrease by approximately 90%, but the overall sensitivity of CAH screening would remain the same. Adding a second-tier genetic step would require a modest increase in costs, but is counterbalanced by fewer recalls, less clinical follow-up, and a reduction in unnecessary worry for families.