Molecular CYP21A2 diagnosis in 480 Brazilian patients with congenital adrenal hyperplasia before newborn screening introduction

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de Carvalho, Daniel F. ; Miranda, Mirela C. ; Gomes, Larissa G. ; Madureira, Guiomar ; Marcondes, Jose A. M. ; Billerbeck, Ana Elisa C. ; Rodrigues, Andresa S. ; Presti, Paula F. ; Kuperman, Hilton ; Damiani, Durval ; Mendonca, Berenice B. ; Bachega, Tania A. S. S.

• Document type: Journal article
• Source: EUROPEAN JOURNAL OF ENDOCRINOLOGY; v. 175, n. 2, p. 107-116, AUG 2016.
• Web of Science Citations: 15

Abstract

Background: Most congenital adrenal hyperplasia (CAH) patients carry CYP21A2 mutations derived from conversion events involving the pseudogene, and the remaining carry new mutations. Objective: To review causal mutations and genotype-phenotype correlation in 480 Brazilian patients. Methods: DNA was extracted from 158 salt-wasters (SWs), 116 simple virilizing (SV), and 206 nonclassical (NC) patients. Fourteen point mutations were screened by allele-specific PCR, large rearrangements by Southern blotting/MLPA, and sequencing was performed in those with incomplete genotype. The gene founder effect was analyzed by microsatellite studies. Patients were divided into six genotypes (Null; A: < 2%; B: 3-7%; C: > 20% of residual enzymatic activity (EA); D: unknown EA; E: incomplete genotype). Results: Targeted methodologies defined genotype in 87.6% of classical and in 80% of NC patients and the addition of sequencing in 100 and 83.5%, respectively. The most frequent mutations were p. V281L (26.6% of alleles), IVS2-13A/C> G (21.1%), and p. I172N (7.5%); seven rare mutations and one novel mutation (p. E351V) were identified. Gene founder effect was observed in all but one (p. W19X) mutation. Null, A, B, and C genotypes correlated with SW (88%), SW (70%), SV (98%), and NC forms (100%), respectively. In group D, the p. E351V mutation correlated with classical form and group E comprised exclusively NC-patients. ACTH-stimulated 17OHP level of 44.3 ng/mL was the best cutoff to identify NC-patients carrying severe mutations. Conclusions: We identified a good genotype-phenotype correlation in CAH, providing useful data regarding prediction of disease ` s severity; moreover, we suggest that ACTH-stimulated 17OHP levels could predict carrier status for severe mutations. Sequencing is essential to optimize molecular diagnosis in Brazilian CAH patients. (AU)

• FAPESP's process: 14/07878-4 - Improving the efficacy of congenital adrenal hyperplasia (CaH) diagnosis in the Brazilian newborn screening (NBs) program
• Grantee: Tania Aparecida Sartori Sanchez Bachega
• Support Opportunities: Regular Research Grants