Clinical Chemistry, Biochemistry and Molecular Biology Operations (UOC), Agostino Gemelli Foundation University Hospital IRCCS, Largo A. Gemelli 8, 00168, Rome, Italy.
Department of Basic Biotechnological Sciences, Intensivological and Perioperative Clinics, Catholic University of Sacred Heart, Rome, Italy.
Mol Diagn Ther. 2023 Sep;27(5):621-630. doi: 10.1007/s40291-023-00666-x. Epub 2023 Aug 7.
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.
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.
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.
This work, representing a comprehensive genetic study, expanded the CYP21A2 variants spectrum of Italian patients with 21OHD and could be helpful in prenatal diagnosis and genetic counseling.
甾体 21-羟化酶基因（CYP21A2）的缺陷导致 21-羟化酶缺乏症（21OHD），这是先天性肾上腺增生症（CAH）的主要病因。该疾病具有广泛的临床表现，从严重或经典型（盐耗竭型，SW，单纯男性化型，SV）到轻度迟发型或非经典型（NC）。21OHD 在严重经典型中发病率为 1/15000，在轻度 NC 型中发病率为 1/200-1000。有许多研究报告了不同人群中 CYP21A2 致病变异的频率；然而，其中很少有研究提供有关意大利患者的综合信息。在这里，我们展示了一组 245 名意大利无关个体的遗传结果，这些个体的临床诊断为 21OHD 导致的 CAH。
采用特定的聚合酶链反应（PCR）方案结合 Sanger 测序进行 CYP21A2 分析。采用多重连接依赖性探针扩增（MLPA）测定拷贝数变异（CNV）。
114 名（46.5%）索引病例为 NC 型，57 名（23.3%）为 SV 型，74 名（30.2%）为 SW 型。在 NC 患者中发现的最常见变异是 p.Val282Leu（51.3%），而在经典型中最常见的变异是 p.Ile173Asn（8.6%）和 c.293-13C>G（26.0%）。在我们的研究中，大片段重排的频率为 15.3%，CAH-X 等位基因占所有 DEL/CONV 的 40%。此外，12 个等位基因携带罕见变异，1 个具有新变异 p.（Arg342Gln）。我们在 94.7%的病例中观察到表型-基因型相关性。在完全缺失酶活性的 Group 0 中观察到完全一致，所有患者均如预期表现为 SW 型。在 Group A（0-1%残留酶活性）中，78.4%的患者出现预期的 SW 型，而 21.6%的患者被诊断为 SV 型。在 Group B（2%残留酶活性）中，93.4%的患者表现为 SV 型，6.5%为 SW 疾病。最后，Group C（酶部分缺失至20-60%残留活性）中 92.6%和 7.4%的患者分别表现为 NC 和 SV 表型。
这项工作代表了一项全面的遗传学研究，扩展了意大利 21OHD 患者 CYP21A2 变异谱，并有助于产前诊断和遗传咨询。
