A novel missense mutation in HSD17B3 gene in a 46, XY adolescent presenting with primary amenorrhea and virilization at puberty

17β-hydroxysteroid dehydrogenases in the progression of nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) has become a worldwide epidemic and a major public health problem, with a prevalence of approximately 25%. The pathogenesis of NAFLD is complex and may be affected by the environment and susceptible genetic factors, resulting in a highly variable disease course and no approved drugs in the clinic. Notably, 17β-hydroxysteroid dehydrogenase type 13 (HSD17B13), which belongs to the 17β-hydroxysteroid dehydrogenase superfamily (HSD17Bs), is closely related to the clinical outcome of liver disease. HSD17Bs consists of fifteen members, most related to steroid and lipid metabolism, and may have the same biological function as HSD17B13. In this review, we highlight recent advances in basic research on the functional activities, major substrates, and key roles of HSD17Bs in the progression of NAFLD to develop innovative anti-NAFLD drugs targeting HSD17Bs.

Disorder of Sex Development Due to 17-Beta-Hydroxysteroid Dehydrogenase Type 3 Deficiency: A Case Report and Review of 70 Different HSD17B3 Mutations Reported in 239 Patients

The 17-beta-hydroxysteroid dehydrogenase type 3 (17-β-HSD3) enzyme converts androstenedione to testosterone and is encoded by the HSD17B3 gene. Homozygous or compound heterozygous HSD17B3 mutations block the synthesis of testosterone in the fetal testis, resulting in a Disorder of Sex Development (DSD). We describe a child raised as a female in whom the discovery of testes in the inguinal canals led to a genetic study by whole exome sequencing (WES) and to the identification of a compound heterozygous mutation of the HSD17B3 gene (c.608C>T, p.Ala203Val, and c.645A>T, p.Glu215Asp). Furthermore, we review all HSD17B3 mutations published so far in cases of 17-β-HSD3 deficiency. A total of 70 different HSD17B3 mutations have so far been reported in 239 patients from 187 families. A total of 118 families had homozygous mutations, 63 had compound heterozygous mutations and six had undetermined genotypes. Mutations occurred in all 11 exons and were missense (55%), splice-site (29%), small deletions and insertions (7%), nonsense (5%), and multiple exon deletions and duplications (2%). Several mutations were recurrent and missense mutations at codon 80 and the splice-site mutation c.277+4A>T each represented 17% of all mutated alleles. These findings may be useful to those involved in the clinical management and genetic diagnosis of this disorder.

Prepubertal and pubertal gonadal morphology, expression of cell lineage markers and hormonal evaluation in two 46,XY siblings with 17β-hydroxysteroid dehydrogenase 3 deficiency

OBJECTIVES

17β-hydroxysteroid dehydrogenase 3 (17β-HSD3) deficiency results in insufficient biosynthesis of testosterone and consequently dihydrotestosterone. This is important for the fetal development of male genitalia. Thus, most 46,XY patients with 17β-HSD3 deficiency have a female appearance at birth and present with virilization at puberty. This study presents the differences in the clinical and hormonal data and analyses of gonadal characteristics in two siblings with 17β-HSD3 deficiency.

CASE PRESENTATION

Patient 1 presented with deepening of the voice and signs of virilization at puberty and increased serum levels of testosterone (T) of 10.9 nmol/L (2.9 SDS) and androstenedione (Δ4) of 27 nmol/L (3.3 SDS) were observed. The T/Δ4-ratio was 0.39. Patient 2 was clinically prepubertal at the time of diagnosis, but she also had increased levels of T at 1.97 nmol/L (2.9 SDS), Δ4 at 5 nmol/L (3.3 SDS), and the T/Δ4-ratio was 0.40, but without signs of virilization. Both siblings were diagnosed as homozygous for the splice-site mutation c.277+4A>T in intron 3 of HSD17B3. They were subsequently gonadectomized and treated with hormone replacement therapy. The gonadal histology was overall in accordance with pubertal status, although with a dysgenetic pattern in both patients, including Sertoli-cell-only tubules, few tubules containing germ cells, and presence of microliths.

CONCLUSIONS

Two siblings with 17β-HSD3 deficiency differed in pubertal development at the time of diagnosis and showed marked differences in their clinical presentation, hormonal profile, gonadal morphology and expression of cell lineage markers. Early diagnosis of 17β-HSD3 deficiency appears beneficial to ameliorate long-term consequences.

Rapid Molecular Genetic Diagnosis with Next-Generation Sequencing in 46,XY Disorders of Sex Development Cases: Efficiency and Cost Assessment

BACKGROUND/AIM

The aim of this study was to use targeted next-generation sequencing (TNGS) including all known genes associated with 46,XY disorders of sex development (DSD) for a fast molecular genetic diagnosis.

METHODS

Twenty pediatric patients were recruited, and 56 genes related to 46,XY DSD were sequenced using TNGS. The time elapsed between initial appointment and final diagnosis as well as the mean expenditure was determined.

RESULTS

A total of 9 (45%) mutations in 4 different genes were identified. Mutations in the HSD17B3 gene were observed in 6 (30%) patients. A heterozygous mutation in WT1 gene and a hemizygous mutation in SRY gene were detected in patients with gonadal dysgenesis. One patient had a homozygous mutation in LHCGR gene. Prior to the molecular diagnosis, the mean number of clinical visits, time elapsed until diagnosis, and expenditure were 27.4 ± 14.6 visits, 5.9 ± 4.1 years per patient, and USD 2,142 ± 1,038, respectively. With TNGS, time elapsed until diagnosis was significantly reduced (3 days), and expenditure per patient was only one third of the conventional approach (USD 761).

CONCLUSIONS

TNGS is an efficient, rapid, and cost-effective technique for mutation detection in 46,XY DSD.

Novel cases of Tunisian patients with mutations in the gene encoding 17β-hydroxysteroid dehydrogenase type 3 and a founder effect

17β-Hydroxysteroid dehydrogenase type 3 (17β-HSD3) is expressed almost exclusively in the testis and converts Δ4-androstene-3,17-dione to testosterone. Mutations in the HSD17B3 gene causing 17β-HSD3 deficiency are responsible for a rare recessive form of 46, XY Disorders of Sex Development (46, XY DSD). We report novel cases of Tunisian patients with 17β-HSD3 deficiency due to previously reported mutations, i.e. p.C206X and p.G133R, as well as a case with the novel compound heterozygous mutations p.C206X and p.Q176P. Moreover, the previously reported polymorphism p.G289S was identified in a heterozygous state in combination with a novel non-coding variant c.54G>T, also in a heterozygous state, in a male patient presenting with micropenis and low testosterone levels. The identification of four different mutations in a cohort of eight patients confirms the generally observed genetic heterogeneity of 17β-HSD3 deficiency. Nevertheless, analysis of DNA from 272 randomly selected healthy controls from the same geographic area (region of Sfax) revealed a high carrier frequency for the p.C206X mutation of approximately 1 in 40. Genotype reconstruction of the affected pedigree members revealed that all p.C206X mutation carriers harbored the same haplotype, indicating inheritance of the mutation from a common ancestor. Thus, the identification of a founder effect and the elevated carrier frequency of the p.C206X mutation emphasize the importance to consider this mutation in the diagnosis and genetic counseling of affected 17β-HSD3 deficiency pedigrees in Tunisia.

46,XY disorder of sex development (DSD) due to 17β-hydroxysteroid dehydrogenase type 3 deficiency

17β-hydroxysteroid dehydrogenase 3 deficiency consists of a defect in the last phase of steroidogenesis, in which androstenedione is converted into testosterone and estrone into estradiol. External genitalia range from female-like to atypical genitalia and most affected males are raised as females. Virilization in subjects with 17β-HSD3 deficiency occurs at the time of puberty and several of them change to male social sex. In male social sex patients, testes can be safely maintained, as long as they are positioned inside the scrotum The phenotype of 46,XY DSD due to 17β-HSD3 deficiency is extremely variable and clinically indistinguishable from other causes of 46,XY DSD such as partial androgen insensitivity syndrome and 5α-reductase 2 deficiency. Laboratory diagnosis is based on a low testosterone/androstenedione ratio due to high serum levels of androstenedione and low levels of testosterone. The disorder is caused by a homozygous or compound heterozygous mutations in the HSD17B3 gene that encodes the 17β-HSD3 isoenzyme leading to an impairment of the conversion of 17-keto into 17-hydroxysteroids. Molecular genetic testing confirms the diagnosis and provides the orientation for genetic counseling. Our proposal in this article is to review the previously reported cases of 17β-HSD3 deficiency adding our own cases.

A Novel Mutation Causing 17-β-Hydroxysteroid Dehydrogenase Type 3 Deficiency in an Omani Child: First Case Report and Review of Literature

This is the first case report in Oman and the Gulf region of a 17-β-hydroxysteroid dehydrogenase type 3 (17-β-HSD3) deficiency with a novel mutation in the HSD17B3 gene that has not been previously described in the medical literature. An Omani child was diagnosed with 17-β-HSD3 deficiency and was followed up for 11 years at the Pediatric Endocrinology Clinic, Royal Hospital, Oman. He presented at the age of six weeks with ambiguous genitalia, stretched penile and bilateral undescended testes. Ultrasound showed no evidence of any uterine or ovarian structures with oval shaped solid structures in both inguinal regions that were confirmed by histology to be testicular tissues with immature seminiferous tubules only. The diagnosis was made by demonstrating low serum testosterone and high androstenedione, estrone, and androstenedione:testosterone ratio. Karyotyping confirmed 46,XY and the infant was raised as male. Testosterone injections (25mg once monthly) were given at two and six months and then three months before his surgeries at five and seven years of age when he underwent multiple operations for orchidopexy and hypospadias correction. At the age of 10 years he developed bilateral gynecomastia (stage 4). Laboratory investigations showed raised follicle-stimulating hormone, luteinizing hormone, androstenedione, and estrone with low-normal testosterone and low androstendiol glucurunide. Testosterone injections (50mg once monthly for six months) were given that resulted in significant reduction in his gynecomastia. Molecular analysis revealed a previously unreported homozygous variant in exon eight of the HSD17B3 gene (NM_000197.1:c.576G>A.Trp192*). This variant creates a premature stop codon, which is very likely to result in a truncated protein or loss of protein production. This is the first report in the medical literature of this novel HSD17B3 gene mutation. A literature review was conducted to identify the previous studies related to this disorder.