Among the disorders of sex development (DSD) with karyotype 46,XY, there is a group of diseases caused by defects of androgen synthesis. The last stage of in the synthesis of androgens is the conversion of testosterone into a more active androgen dihydrotestosterone, which occurs under the influence of the enzyme 5α-reductase type II (SRD5A2). SRD5A2 deficiency is a rare disease with autosomal recessive inheritance. To give a clinical and molecular genetic characterization of 14 new cases with confirmed molecular diagnosis of SRD5A2 deficiency, as well as 4 cases of DSD 46,XY, where monoallelic changes in the SRD5A2 gene were detected. The study included 310 patients with DSD 46,XY. Molecular genetic analysis was performed using the NGS method using a targeted panel for multiplex amplification and subsequent sequencing of the coding regions of the following genes: AKR1C2, AKR1C4, AMH, AMHR2, AR, ARX, ATRX, CBX2, CYB5A, CYP11A1, CYP17A1, DHCR7, DHH, EMX2, ESR2, FGD1, FGF9, FGFR2, FKBP4, FOXF2, FOXL2, HOXA13, HSD17B3, HSD3B2, ICK, LHCGR, LHX1, LHX9, MAMLD1, MAP3K1, MID1, NR0B1, NR5A1, POR, PTGDS, SOX9, SRD5A2, SRY, STAR, SUPT3H, TSPYL1, WNT4, WT1, ZFPM2. By molecular genetic analysis 16 different variants were identified in the SRD5A2 gene (2 in several families), 4 of which had not been previously described. The study highlights the importance of molecular genetic analysis in the differential diagnosis of DSD 46,XY. АКТУАЛЬНОСТЬ. В структуре нарушений формирования пола (НФП) при кариотипе 46,XY выделяют группу нозологий, обусловленных нарушением синтеза андрогенов, последним этапом которого является превращение тестостерона в более активный андроген дигидротестостерон, что происходит под влиянием фермента 5α-редуктазы II типа (SRD5A2). Дефицит SRD5A2 является редким заболеванием с аутосомно-рецессивным наследованием. ЦЕЛЬ. Дать клиническую и молекулярно-генетическую характеристику 14 новых случаев с подтвержденным молекулярно-генетическим методом дефицитом SRD5A2, а также 4 случаев НФП 46,XY, где были выявлены моноаллельные изменения в гене SRD5A2. МАТЕРИАЛЫ И МЕТОДЫ. В исследование было включено 310 пациентов с НФП 46,XY. Молекулярно-генетический анализ проводился методом NGS с использованием таргетной панели для мультиплексной амплификации и последующего секвенирования кодирующих последовательностей следующих генов: AKR1C2, AKR1C4, AMH, AMHR2, AR, ARX, ATRX, CBX2, CYB5A, CYP11A1, CYP17A1, DHCR7, DHH, EMX2, ESR2, FGD1, FGF9, FGFR2, FKBP4, FOXF2, FOXL2, HOXA13, HSD17B3, HSD3B2, ICK, LHCGR, LHX1, LHX9, MAMLD1, MAP3K1, MID1, NR0B1, NR5A1, POR, PTGDS, SOX9, SRD5A2, SRY, STAR, SUPT3H, TSPYL1, WNT4, WT1, ZFPM2. РЕЗУЛЬТАТЫ. При молекулярно-генетическом обследовании в гене SRD5A2 было идентифицировано 16 различных вариантов (2 — в нескольких семьях), 4 из которых ранее описаны не были. ЗАКЛЮЧЕНИЕ. Проведенное исследование подчеркивает важное значение молекулярно-генетического анализа в дифференциальной диагностике НФП 46,XY.

Precise and timely diagnosis is essential in the management of children born with atypical genitalia/differences or disorders of sex development (DSD) to provide optimal personalised care. Establishing the diagnosis can be challenging and time-consuming. The human chorionic gonadotrophin (hCG) stimulation test is useful in assessing male gonadal function, and stimulated testosterone: 5α-dihydrotestosterone (T:DHT)>10 suggests 5-alpha reductase type 2 (SRD5A2) deficiency. We report the clinical, hormonal and genetic data of patients with 46, XY DSD with genetically confirmed SRD5A2 deficiency to assess the value of the hCG-stimulated T:DHT ratio in the diagnostic work-up. Additionally, we reviewed the literature on the usefulness of hCG-stimulated androgen ratios in determining DSD aetiology. Of 14 patients with genetically confirmed SRD5A2 deficiency, including one novel variant, nine underwent hCG stimulation test: seven in infancy, one at 4 years and one at puberty. A T:DHT ratio above 10 was observed in seven patients (median: 15; range: 10.7-66.5). Two patients, aged one month and 4 years, had ratios of 8.3 and 4.4, respectively. Urinary steroid profiling (GC/MS) suggested SRD5A2 deficiency in all patients who had the testing (n=13). No association was found between T:DHT ratios and age at presentation or external masculinisation score (EMS). The hCG stimulation test appears less sensitive than urinary steroid profiling in establishing the diagnosis of SRD5A2 deficiency.

17β-Hydroxysteroid dehydrogenase 3 deficiency (17β-HSDD) and 5α-reductase type 2 deficiency (5α-RD) are rare 46,XY differences of sex development (DSD). This study aims to enlarge the limited knowledge on long-term gonadal function and gonadal pathology in these conditions. Retrospective multicentre cohort study. Data on phenotype, laboratory results, and hormone treatment were collected from patients aged ≥16 years at time of data collection with genetically confirmed 17β-HSDD and 5α-RD from 10 centres via the I-DSD Registry. If gonadectomy or gonadal biopsy had been performed, pathology reports and/or gonadal tissue or images were collected. All 16 patients with 17β-HSDD were raised female; 1 (6%) changed to male gender at age 14. Three females were treated with gonadotrophin-releasing hormone agonists (GnRHa) to prevent virilisation. Thirteen underwent gonadectomy at median age 8 (range 0-17). None had germ cell (pre)malignancies. Of 14 patients with 5α-RD, 10 (71%) were raised female. Five changed gender at age 7-23, of whom 4 to male gender. One was treated with GnRHa. Six underwent gonadectomy at median age 10 (range 0-31). None had germ cell (pre)malignancies. With gonads in situ, puberty spontaneously progressed. Three were treated with dihydrotestosterone. A significant percentage of individuals with 17β-HSDD and 5α-RD changed gender, and some were treated with GnRHa to prevent virilisation before making a definitive decision about gonadectomy. When left in situ, spontaneous puberty occurs and germ cell (pre)malignancies seem uncommon at least until early adulthood. Together, these data support delaying a decision about gonadectomy until late adolescence in these conditions.

To investigate the value of the human chorionic gonadotropin (hCG) stimulation test in the diagnosis of disorder of sexual development (DSD) in children. A retrospective analysis was conducted on 132 children with DSD. According to the karyotype, they were divided into three groups: 46,XX group (n=10), 46,XY group (n=87), and sex chromosome abnormality group (n=35). The above groups were compared in terms of sex hormone levels before and after hCG stimulation test, and the morphological manifestation of the impact of testicular tissue on the results of the hCG stimulation test was analyzed. There was no significant difference in the multiple increase of testosterone after stimulation among the three groups (P>0.05). In the 46,XY group, the children with 5α-reductase type 2 deficiency had a testosterone-to-dihydrotestosterone ratio higher than that of the 46,XY DSD children with other causes. Morphological analysis showed that DSD children with testicular tissue demonstrated a significantly higher multiple increase in testosterone after stimulation compared to children without testicular tissue (P<0.05). The hCG stimulation test has an important value in assessing the presence and function of testicular interstitial cells in children with different types of DSD, and it is recommended to perform the hCG stimulation test for DSD children with unclear gonadal type. 目的: 探讨人绒毛膜促性腺激素（human chorionic gonadotrophin, hCG）激发试验在诊断不同分型性发育异常（disorder of sexual development, DSD）患儿中的价值。方法: 回顾性分析132例DSD患儿，按染色体核型分为46,XX组（n=10）、46,XY组（n=87）、性染色体异常组（n=35），比较各组患儿hCG激发试验前后的性激素水平，分析形态学上是否存在睾丸组织对hCG激发试验结果的影响。结果: 3组患儿激发试验后睾酮（testosterone, T）增加倍数比较差异无统计学意义（P>0.05）。46,XY组中，5α-还原酶2缺乏症患儿激发试验后的T与双氢睾酮（dihydrotestosterone, DHT）比值高于其他46,XY DSD患儿（P<0.05）。形态学上，有睾丸组织的DSD患儿激发试验后T增加倍数高于无睾丸组织患儿（P<0.05）。结论: hCG激发试验对于评估不同类型的DSD患儿的睾丸间质细胞存在和功能均具有重要价值，对于性腺性质不明确的DSD患儿，均建议行hCG激发试验。.

Steroid 5α-reductase type 2 deficiency (5α-RD2) is an autosomal recessive disorder caused by mutations in the SRD5A2 gene. This condition is characterized by reduced enzymatic activity of the 5α-reductase type 2 enzyme. Individuals with mutations in the SRD5A2 gene may exhibit various symptoms of under-masculinization in 46, XY individuals. We conducted a comprehensive analysis of the SRD5A2 gene in a patient with disorder of sex development (DSD). We describe a patient with a homozygous Gly183Ser variant in the SRD5A2 gene. Their sibling also carries this variant in homozygosity, while both parents have it in a heterozygous state. The patient presents with predominantly female traits and was raised as a girl. Although the siblings exhibit distinct phenotypic characteristics, both have assumed a male gender identity. This study reveals different phenotypes for the two siblings, highlighting the complexity of establishing a genotype-phenotype correlation in the SRD5A2 gene. It is noteworthy that the Gly183Ser variant seems to be more prevalent among individuals of African descent, aligning with our patient's ethnic background.