A compound heterozygous mutation in the CYP17 (17alpha-hydroxylase/17,20-lyase) gene in a Chinese subject with congenital adrenal hyperplasia

A Patient with Partial 17α-Hydroxylase Deficiency Initially Diagnosed with Asherman Syndrome and Pheochromocytoma

This study present a case of a 49-year-old woman who suffered from resistant hypertension, hypokalemia, hypomenorrhea, and infertility. She was hospitalized 6 years earlier for hypomenorrhea and abdominal pain at the Xiamen Maternity and Child Health Hospital, where she was diagnosed with Asherman syndrome. During hospitalization, a computed tomography examination revealed an adrenal mass. She was referred to Xiamen University Affiliated Zhongshan Hospital for pheochromocytoma and underwent surgical resection of the left adrenal gland. The adrenal cortex adenoma was confirmed by pathological biopsy. Six years later, the patient also presented with hypertension and hypokalemia to our emergency department. A diagnosis of 17α-hydroxylase deficiency was established through the analysis of clinical and laboratory characteristics. The genetic analysis of CYP17A1 revealed compound heterozygous mutations, 1 of which was a mutation of c.1226 C>G, and the other c.297+2T>C.

Molecular regulation of steroidogenesis in endocrine Leydig cells

Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. Consequently, the process of steroid hormone biosynthesis is finely regulated. In the testis, the main steroidogenic cells are the Leydig cells. There are two distinct populations of Leydig cells that arise during development: fetal and adult Leydig cells. Fetal Leydig cells are responsible for masculinizing the male urogenital tract and inducing testis descent. These cells atrophy shortly after birth and do not contribute to the adult Leydig cell population. Adult Leydig cells derive from undifferentiated precursors present after birth and become fully steroidogenic at puberty. The differentiation of both Leydig cell populations is controlled by locally produced paracrine factors and by endocrine hormones. In fully differentially and steroidogenically active Leydig cells, androgen production and hormone-responsiveness involve various signaling pathways and downstream transcription factors. This review article focuses on recent developments regarding the origin and function of Leydig cells, the regulation of their differentiation by signaling molecules, hormones, and structural changes, the signaling pathways, kinases, and transcription factors involved in their differentiation and in mediating LH-responsiveness, as well as the fine-tuning mechanisms that ensure adequate production steroid hormones.

Clinical and genetic analyses of a Chinese female with 17α-hydroxylase/17,20-lyase deficiency

AIMS

17α-Hydroxylase/17,20-lyase deficiency (17OHD) is a rare autosomal recessive disease caused by CYP17 gene mutations. This disease is clinically characterised by hypertension, hypokalaemia, sexual infantilism in females or pseudohermaphroditism in males, and adrenal hyperplasia. This study aims to investigate a rare case of 17OHD accompanied by both cystic ovaries and massive adrenal mass.

METHODS

This study performed clinical, hormonal, radiological and genetic analyses. Blood samples were collected from the patient for the genetic test. Genomic DNA was extracted from peripheral blood leukocytes, and the coding sequence abnormalities of CYP17 were assessed using polymerase chain reaction and direct sequencing analysis.

RESULTS

The genetic analysis of CYP17 revealed compound heterozygous mutations in the individual. One was a mis-sense mutation of c.1226 C > G, which changes codon 409 in exon 7 from proline (CCG) to arginine (CGG). Another was a mutation of p.Val311Asp,fs,330X, which was first reported in a compound heterozygote mutation of Y329fs and V311fs from a Chinese patient.

CONCLUSION

This study presented a rare case of 17OHD accompanied by both cystic ovaries and massive adrenal mass. This study obtained significant information on the genotype-phenotype correlation of 17OHD.

Phenotypic variation in a Chinese family with 46,XY and 46,XX 17α-hydroxylase deficiency

BACKGROUND

17α-hydroxylase deficiency is a rare autosomal recessive disorder characterized by sexual infantilism, amenorrhea, hypertension and hypokalemia, which is caused by mutations in the CYP17A1 gene. To date, more than 50 mutations in this gene have been described.

METHODS

The clinical features and biochemical data of a pair of 46,XY and 46,XX Chinese siblings with 17α-hydroxylase deficiency from Singapore were studied. Direct DNA sequence analysis of the CYP17A1 gene was performed.

RESULTS

There was significant phenotypic variation between the siblings. The proband (46,XY) presented classically with sexual infantilism, amenorrhea and hypertension. The younger sibling (46,XX) also presented with amenorrhea, but she had breast development and absence of hypokalemic hypertension. The same compound heterozygous mutations in CYP17A1 gene were identified in both patients. A missense mutation (P409R) was detected in exon 7, and a 9-bp deletion (D487-S488-F489del) was detected in exon 8.

CONCLUSION

We confirmed the diagnosis of 17α-hydroxylase deficiency in these two patients. Both P409R and D487-S488-F489del have been described previously and are widely propagated in the Chinese population in East and Southeast Asia. We propose that the phenotypic expression of affected individuals with 17α-hydroxylase deficiency is karyotype-dependent, with individuals having the 46,XX karyotype having less pronounced clinical symptoms.

CYP17A1 intron mutation causing cryptic splicing in 17α-hydroxylase deficiency

17α-hydroxylase/17, 20-lyase deficiency (17OHD) is an autosomal recessive disease causing congenital adrenal hyperplasia and a rare cause of hypertension with hypokalemia. The CYP17A1 gene mutation leads to 17OHD and its clinical features. We described an 18 y/o female with clinical features of 17α-hydroxylase/17, 20-lyase deficiency and characterized the functional consequences of an intronic CYP17A1 mutation. The coding regions and flanking intronic bases of the CYP17A1 gene were amplified by PCR and sequenced. The patient is a compound heterozygote for the previously described p.R358X and IVS1 +2T>C mutations. A first intron splice donor site mutation was re-created in minigene and full-length expression vectors. Pre-mRNA splicing of the variant CYP17A1 intron was studied in transfected cells and in a transformed lymphoblastoid cell line. When the full-length CYP17A1 gene and minigene containing the intronic mutation was expressed in transfected cells, the majority (>90%) of mRNA transcripts were incorrectly spliced. Only the p.R358X transcript was detected in the EBV-transformed lymphoblastoid cell line. The IVS1 +2T>C mutation abolished most 17α-hydroxylase/17, 20-lyase enzyme activity by aberrant mRNA splicing to an intronic pseudo-exon, causing a frame shift and early termination.

Rare hypertension as a result of 17alpha-hydroxylase deficiency

PURPOSE

To investigate CYP 7A1 gene mutations in Chinese patients with 17alpha-hydroxylase deficiency.

METHODS

Clinical data were retrospectively analyzed. CYP17A1 mutations were detected in two cases with 17alpha-hydroxylase deficiency. Genomic DNA was isolated from blood samples and eight primers pairs were used to amplify eight exons and exon-intron boundaries of the CYP17A1 gene. The amplified PCR products were purified by agarose gel electrophoresis and then directly sequenced. Sequencing results were compared to the established human CYP17A1 sequence.

RESULTS

Two compound mutations were identified: TAC --> AA at codons 436-438 on exon 6, causing the amino acid missense mutation Y329K/418X; and deletion of the 9-bp sequence GACTCTTTC at codons 487-489 on exon 8, causing deletion of three amino acids (Asp-Ser-Phe).

CONCLUSION

D487_F489del and Y329K, 418X CYP17A1 mutations were identified in our two patients. A literature review revealed that the main CYP17A1 mutations in the Chinese population are missense and splicing defects, and exons 8 and 6 are most frequently involved.

17-alpha-hydroxylase deficiency: a case report with clinical and molecular analysis

BACKGROUND

17alpha-Hydroxylase deficiency (17OHD) is a rare disease of congenital adrenal hyperplasia. It is characterised by hypertension, hypokalaemia, primary amenorrhoea. Deficiency of P450c17 enzyme is caused by mutation of the CYP17 gene.

CASE

A 16-year-old female with genotypic 46, XY suffered from 17OHD. She presented with primary amenorrhoea, lack of secondary sexual characteristics, and hypertension. Laboratory tests showed hypokalaemia, low levels of androgens (testosterone and dehydroepiandrosterone), corticosteroid, and high levels of adrenocorticotropic hormone and progesterone. A P409R mutation was found in exon7 of CYP17 gene, revealing homozygosis and confirming diagnosis of 17OHD.

CONCLUSION

17OHD is a rare disease associated with primary amenorrhoea and hypertension. Identification of mutation in CYP17 gene can help to a better understanding of this enzyme deficiency.

Molecular modeling on inhibitor complexes and active-site dynamics of cytochrome P450 C17, a target for prostate cancer therapy

A molecular model for the P450 enzyme cytochrome P450 C17 (CYP17) is presented based on sequence alignments of multiple template structures and homology modeling. This enzyme plays a central role in the biosynthesis of testosterone and is emerging as a major target in prostate cancer, with the recently developed inhibitor abiraterone currently in advanced clinical trials. The model is described in detail, together with its validation, by providing structural explanations to available site-directed mutagenesis data. The CYP17 molecule in this model is in the form of a triangular prism, with an edge of approximately 55 A and a thickness of approximately 37 A. It is predominantly helical, comprising 13 alpha helices interspersed by six 3(10) helices and 11 beta-sheets. Multinanosecond molecular dynamics simulations in explicit solvent have been carried out, and principal components analysis has been used to reveal the details of dynamics around the active site. Coarse-grained methods have also been used to verify low-frequency motions, which have been correlated with active-site gating. The work also describes the results of docking synthetic inhibitors, including the drug abiraterone and the natural substrate pregnenolone, in the CYP17 active site together with molecular dynamics simulations on the complexes.

Loss of cytochrome P450 17A1 protein expression in a 17alpha-hydroxylase/17,20-lyase-deficient 46,XY female caused by two novel mutations in the CYP17A1 gene

17alpha-Hydroxylase deficiency (17OHD) is a rare form of congenital adrenal hyperplasia caused by mutations in the CYP17A1 gene. This condition shows considerable clinical and biochemical variation. Molecular characterization of novel mutations in the CYP17A1 gene and detailed study of their structural, enzymatic, and clinical consequences are required to fully understand enzyme behavior. Here, we present the first molecular characterization of two novel mutations in CYP17A1 in a 15-year-old female Mexican mestizo 46,XY female with primary amenorrhea and lack of pubertal development and severe hypertension that manifested only after surgery. A complete clinical and biochemical evaluation was compatible with 17OHD. Structural anomalies in the CYP17A1 gene were discovered by direct automated sequencing, which revealed a novel compound heterozygous K110X/R362H mutation that leads to a complete lack of enzyme activity. Immunohistochemical analyses performed to determine protein expression and localization showed that cytochrome P450 17A1 was completely absent in the patient's testicular tissue. Studies of novel mutations, such as those described here, provide important information that allows us to better understand the effect of a given mutation on enzyme function and to observe the impact of the mutation on clinical phenotype.