Prevalence of CYP17A1 gene mutations in 17α-hydroxylase deficiency in the Chinese Han population

A Case Report of 17α-Hydroxylase Deficiency in Two Saudi Siblings With Different Karyotyping

Congenital adrenal hyperplasia (CAH) consists of variable disorders of sex determination and differentiation. 17α-hydroxylase deficiency (17OHD) is an uncommon form of those disorders, which is typically characterized by hypertension, hypokalemia, failure of puberty, and ambiguous genitalia. The 17α-hydroxylase enzyme is encoded by the CYP17A1 gene and it is required for the synthesis of cortisol and sex steroids. The affected females with 17OHD usually present with primary amenorrhea and delayed puberty, which are associated with hypertension and hypokalemia while male patients might show female external genitalia, pseudohermaphroditism, or variable degrees of ambiguous genitalia with intra-abdominal testes in addition to hypertension and hypokalemia as well. We present two Saudi siblings (19 and 16 years old) who were diagnosed with the rare CAH subtype of 17OHD after presenting with long-standing hypertension, refractory hypokalemia, and failure of puberty. It is interesting that both siblings had biochemical primary adrenal insufficiency; however, both patients did not clinically present with an acute adrenal crisis, which is likely due to the effect of increased levels of deoxycorticosterone. Additionally, although both patients have similar phenotypes and clinical presentations, they have different karyotypes. This again highlights the variability of the manifestations that can result from 17OHD even with an identical mutation in the same family. Both patients were treated successfully with dexamethasone, which has led to the normalization of hypertension, resolution of hypokalemia, and discontinuation of anti-hypertensive medications and potassium supplements after several years of treatment. However, the entire management is quite challenging and requires a multidisciplinary approach regarding difficult issues such as gender identity and assignment and fertility issues in addition to a life-long follow-up.

Genetic diagnosis and clinical analysis of 17α-hydroxylase/17, 20-lyase deficiency combined with type 2 diabetes mellitus: A case report

RATIONALE

17α-Hydroxylase/17, 20-lyase deficiency (17OHD) is a recessively inherited autosomal disease caused by CYP17A1 gene mutations. It is characterized by failure to synthesize cortisol, adrenal androgens and gonadal steroids. However, it is rare in clinic combining with type 2 diabetes mellitus (T2DM).

PATIENT CONCERNS

A 21-year-old woman was transferred to an endocrinology clinic because of paroxysmal paralysis. In addition, she presented with hypertension, primary amenorrhea and lack of pubertal development. Blood evaluation revealed hypokalemia, and a low cortisol level with an increased adrenocorticotropic hormone concentration. The renin activity and testosterone and estrogen levels were suppressed, and the gonadotropin levels were high. CT scan showed bilateral adrenal hyperplasia. Besides, this patient had hyperglycemia, hyperinsulinism and negative diabetes type 1 related antibodies. A homozygous mutation c. 985 to 987delinsAA in exon 6 was found in the patient which caused the missense mutation (p.Y329fs).

DIAGNOSES

17α-hydroxylase/17, 20-lyase deficiency combined with T2DM was considered.

INTERVENTIONS

The patient received dexamethasone, estradiol valerate, metformin, amlodipine besylate and D3 calcium carbonate tablets. The doses of dexamethasone was changed according to her blood potassium levels.

OUTCOMES

After treatment, the blood pressure, blood potassium and blood glucose returned to normal range. Besides, she had restored her menstrual cycle.

LESSONS

For patients with hypertension, hypokalemia and lack of pubertal development, the possibility of 17OHD should be considered. The subsequent treatment would be challenging in patients with combined 17OHD and T2DM, considering the potential contribution of glucocorticoids to diabetic balance and osteoporosis.

A Chinese girl with delayed puberty due to 17α-hydroxylase deficiency: the diagnosis, treatment and monitoring approach

Summary

17α-hydroxylase deficiency (17α-OHD) is a rare form of congenital adrenal hyperplasia. We report the case of a teenage girl with 17α-OHD who presented with delayed puberty, hypergonadotropic hypogonadism and hypertension. We illustrate the clinical approach in workup, the subsequent management and monitoring of this rare condition.

Learning points

17α-hydroxylase deficiency (17α-OHD) should be considered as a rare yet important differential diagnosis of girls with delayed puberty and elevated gonadotropins. Urine steroid profile, plasma aldosterone and renin levels should be assessed in adolescent girls with hypergonadotropic hypogonadism, after the exclusion of more common conditions, e.g. Turner syndrome. Inhibiting deoxycorticosterone (DOC) release by partial glucocorticoid replacement, counteracting DOC's mineralocorticoid effects by antagonists (such as eplerenone or spironolactone) as well as sex hormone replacements constitute the major backbone in the management of 17α-OHD.

Refractory hypokalemia with sexual dysplasia and infertility caused by 17α-hydroxylase deficiency and triple X syndrome: A case report

The present study reports a patient case with a 17α-hydroxylase deficiency accompanied by triple X syndrome. A 17α-hydroxylase deficiency leads to a very low 17α-hydroxylated steroid synthesis as well as a non-feedback increase in the adrenocorticotropic hormone level. Meanwhile, the progesterone level increases the 17α-hydroxyprogesterone level and decreases the dehydroepiandrosterone sulfate level. The patient is characterized by intractable hypokalemia, high urinary potassium, hyperaldosteronemia, hyporeninemia, hypocortisolemia, hypertension, gonadal and secondary sexual dysplasia, a decreased estrogen level, primary amenorrhea, and infertility. The imaging findings indicate a presence of multiple bilateral adrenal gland adenomas, and the sequencing indicates a missense CYP17A1-E7 gene pathogenic variant. The karyotype is a 47, XXX [3]/46, XX [47] low-level chimeric karyotype. The patient's parents are cousins. To our knowledge, this patient is the first case diagnosed with congenital adrenal hyperplasia caused by hydroxylase deficiency and triple X syndrome. The uniqueness of this case is that this patient has two very rare genetic diseases, probably due to the marriage of close relatives.

17 alpha-hydroxylase deficiency: A case report of young Chinese woman with a rare gene mutation

We report a young adult woman with 17 alpha-hydroxylase deficiency (17α-OHD) in Shandong province of China. The patient carried compound heterozygous mutations in the CYP17A1 gene: c.985-987 delinsAA (p.Tyr329LysfsX90) and c.1486C > T (p.Arg496Cys). The patient's hypertension and hypokalemia were resolved after taking medications of glucocorticoid, aldactone, and calcium antagonists.

Case report: 17α- hydroxylase deficiency due to a hotspot variant and a novel compound heterozygous variant in the CYP17A1 gene of five Chinese patients

17α-Hydroxylase deficiency (17OHD) is a rare form of congenital adrenal hyperplasia caused by mutations in the CYP17A1 gene. It is characterized by impaired adrenal and gonad steroid biosynthesis. Affected patients present with hypertension, hypokalemia, and disorders of sexual development. Here, we describe the genotypes and phenotypes of five patients from three families with this rare disease. Most patients had the hotspot variant, c.985_987delTACinsAA, in CYP17A1, which may be caused by a founder effect. However, the patients in our study were younger than the typical age of onset of 17OHD, and there was a pair of twins with the karyotypes 46, XX and 46, XY, but they both had a female phenotype. Meanwhile, we identified a novel compound heterozygous variant, c.1243+6T>G (p.Y329fs/splicing) in the CYP17A1 gene.

Ovarian gonadoblastoma with dysgerminoma in a girl with 46,XX karyotype 17a-hydroxylase/17, 20-lyase deficiency: A case report and literature review

17α-hydroxylase/17,20-lyase deficiency (17-OHD), caused by mutations in the gene of the cytochrome P450 family 17 subfamily A member 1 (CYP17A1), is a rare type of congenital adrenal hyperplasia (CAH), usually characterized by cortisol and sex steroid deficiency combined with excessive mineralocorticoid. Gonadoblastoma is a relatively rare ovarian tumor that is frequently seen among patients with 46,XY gonadal dysgenesis. Rarely have they been reported in female patients with normal 46,XX karyotype. Here, we report an interesting case of an 11-year-old Chinese girl who presented acute abdominal pain that was later attributed to tumor rupture of right ovarian gonadoblastoma with dysgerminoma. Further evaluations revealed hypertension and hypokalemia. Hormonal findings showed increased progesterone, hypergonadotropic hypogonadism, and low cortisol levels. Her chromosome karyotype was 46,XX without Y chromosome material detected. Genetic analysis revealed that the patient had a homozygous pathogenic variant c.985_987delTACinsAA (p.Y329Kfs*90) in exon 6 of the CYP17A1 gene and that her parents were all heterozygous carriers of this pathogenic variant. Due to the variable clinical manifestations of 17-OHD, meticulous assessment including genetic analysis is necessary. Further study is warranted to unravel the mechanism of gonadoblastoma in a patient with normal karyotypes.

Novel mutations of the CYP17A1 gene in four Chinese 46,XX cases with partial 17a-hydroxylase/17,20-lyase deficiency

The condition 17a-Hydroxylase/17,20-lyase deficiency (17-OHD) is a rare kind of congenital adrenal hyperplasia (CAH) characterized by failure to synthetize cortisol, adrenal androgens and gonadal steroids. Partial deficiency is much rarer, presenting with subtler symptoms. In this study, we summarized the clinical characteristics and identified the underlying gene mutation in four Chinese 46,XX patients with partial 17-OHD. Mutational analysis of the CYP17A1 gene was performed by polymerase chain reaction (PCR) and Sanger sequencing. Clinical and hormonal findings in these patients were consistent with typical manifestations of partial 17-OHD. All patients were found to have a compound heterozygous mutation of the CYP17A1 gene, with five mutations identified. Among them, c.887 T > C(p. I296T), c.1019G > A(p. R340H) and c.1346G > A(p. R449H) were novel missense mutations. In conclusion, we identified three novel missense mutations of the CYP17A1 gene from four patients with partial 17-OHD deficiency. Genotype-phenotype correlation analysis revealed that these novel mutations can lead to partial 17-OHD. Our findings thus provide novel insight into the clinical evaluations and molecular basis of 17-OHD.

Clinical and Genetic Characteristics of 17 α-Hydroxylase/17, 20-Lyase Deficiency: c.985_987delTACinsAA Mutation of CYP17A1 Prevalent in the Chinese Han Population

OBJECTIVE

17 α-hydroxylase/17, 20-lyase deficiency (17-OHD) is a rare recessive hereditary disease that can be attributed to cytochrome P450 17 α-hydroxylase deficiency caused by CYP17A1 gene mutations.

METHODS

A large cohort of 10 Chinese Han patients with 17-OHD from 2012 to 2020 were enrolled. The clinical and biochemical features were investigated, and genetic mutations of CYP17A1 were analyzed by polymerase chain reaction-Sanger sequencing. Karyotype identification and the SRY gene test were also carried out. In silico analysis was used to predict the effects of genetic mutations on the protein function.

RESULTS

All patients were female. Common complaints were hypertension, hypokalemia, and primary amenorrhea. The karyotype was 46, XY, and the SRY gene was detected in 7 patients; the karyotype was XX in the remaining 3 patients. A total of 7 mutations including Y329N, Y329X, Y329Lfs∗, R96W, A82D, S380N, and A487_P489del have been identified in the CYP17A1 gene. The Y329Lfs∗ mutation was found in 9/10 (90%) of patients with a high allele frequency of 70%. In silico prediction showed that a novel variant of c.1139G>A (S380N) occurs at a conserved residue and can cause disease.

CONCLUSION

We presented a detailed description of the clinical and genetic characteristics in Chinese patients with 17-OHD and concluded that Y329Lfs∗ mutation of CYP17A1 is prevalent in the Chinese Han population. Therefore, hotspot screening by polymerase chain reaction-Sanger sequencing for exon 6 of CYP17A1 could contribute to the rapid diagnosis of 17-OHD in China. Genetic counseling based on the genetic diagnosis for at-risk relatives is advised.

Comparative Dynamics and Functional Mechanisms of the CYP17A1 Tunnels Regulated by Ligand Binding

As an important member of cytochrome P450 (CYP) enzymes, CYP17A1 is a dual-function monooxygenase with a critical role in the synthesis of many human steroid hormones, making it an attractive therapeutic target. The emerging structural information about CYP17A1 and the growing number of inhibitors for these enzymes call for a systematic strategy to delineate and classify mechanisms of ligand transport through tunnels that control catalytic activity. In this work, we applied an integrated computational strategy to different CYP17A1 systems with a panel of ligands to systematically study at the atomic level the mechanism of ligand-binding and tunneling dynamics. Atomistic simulations and binding free energy computations identify the dynamics of dominant tunnels and characterize energetic properties of critical residues responsible for ligand binding. The common transporting pathways including S, 3, and 2c tunnels were identified in CYP17A1 binding systems, while the 2c tunnel is a newly formed pathway upon ligand binding. We employed and integrated several computational approaches including the analysis of functional motions and sequence conservation, atomistic modeling of dynamic residue interaction networks, and perturbation response scanning analysis to dissect ligand tunneling mechanisms. The results revealed the hinge-binding and sliding motions as main functional modes of the tunnel dynamic, and a group of mediating residues as key regulators of tunnel conformational dynamics and allosteric communications. We have also examined and quantified the mutational effects on the tunnel composition, conformational dynamics, and long-range allosteric behavior. The results of this investigation are fully consistent with the experimental data, providing novel rationale to the experiments and offering valuable insights into the relationships between the structure and function of the channel networks and a robust atomistic model of activation mechanisms and allosteric interactions in CYP enzymes.