Genetic Characterization of a Cohort of Italian Patients with Congenital Adrenal Hyperplasia Due to 21-Hydroxylase Deficiency
Molecular diagnosis & therapy(2023)
摘要
Introduction Defects in the steroid 21-hydroxylase gene ( CYP21A2 ) cause 21-hydroxylase deficiency (21OHD), the main cause of congenital adrenal hyperplasia (CAH). The disease shows a broad spectrum of clinical forms, ranging from severe or classical (salt wasting, SW, and simple virilizing, SV), to mild late onset or nonclassical (NC). 21OHD affects 1 in 15,000 in its severe classic form and 1 in 200–1000 in its mild NC form. There are many studies reporting the frequency of CYP21A2 pathogenic variants in different populations; however, few of them provide comprehensive information about Italian patients. Here, we present genetic results from a cohort of 245 unrelated Italian individuals with clinical diagnosis of CAH due to 21OHD. Methods A specific polymerase chain reaction (PCR) protocol combined with Sanger sequencing was used for CYP21A2 analysis. The multiplex ligation-dependent probe amplification (MLPA) assay was employed for copy number variation (CNV) determination. Results One hundred fourteen (46.5%) of the index cases had the NC form, 57 (23.3%) had the SV form, and 74 (30.2%) presented the SW form of the disease. The most prevalent variant found in NC patients was the p.Val282Leu (51.3%), while the most frequent variants in the classical form were p.Ile173Asn (8.6%) and c.293-13C>G (26.0%). In our study, the frequency of large rearrangements was 15.3%, with CAH-X alleles representing 40% of all DEL/CONV. In addition, 12 alleles carried rare variants, and 1 had a novel variant p.(Arg342Gln). We observed phenotype-genotype correlation in 94.7% of cases. A complete concordance was observed in Groups 0 (enzyme activity completely impaired) where all patients had the SW form as expected. In Group A (0–1% residual enzyme activity), 78.4% of patients had the anticipated SW form while 21.6% were diagnosed with the SV form. Within Group B (~ 2% residual enzyme activity), 93.4% of patients exhibited SV form and 6.5% SW disease. Finally, 92.6% and 7.4% of patients belonging to Group C (enzyme partially impaired to ~ 20–60% residual activity) exhibited NC and SV phenotypes, respectively. Conclusion This work, representing a comprehensive genetic study, expanded the CYP21A 2 variants spectrum of Italian patients with 21OHD and could be helpful in prenatal diagnosis and genetic counseling.
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关键词
congenital adrenal hyperplasia,deficiency,italian patients,genetic
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