ESPE Abstracts

X-linked hypophosphatemia (XLH) is the most common genetic disorder of phosphate homeostasis. It is caused by inactivating mutations in the PHEX gene, which encodes a phosphate regulating endopeptidase predominantly expressed in osteoblasts, osteocytes, and odontoblasts.In children there is a broad phenotypic spectrum of XLH ranging from isolated hypophosphatemia without clinical signs up to severe symptoms, such as rickets, extreme lower limb d...

Aim: To study the mutation spectrum in SRD5A2 and AR genes among Indian children with 46 XY disorders of sex development (DSD).Methods: This work is part of an ongoing study at Department of Pediatrics, AIIMS, Delhi, approved by the ethics committee of the Institute. Children with 46 XY DSD in whom endocrine investigations were suggestive of either 5α reductase deficiency or androgen insensitivity syndrome were enrolled for mutatio...

Duplications of the dosage sensitive sex locus Xp21.2 have been associated with 46,XY gonadal dysgenesis (GD) for nearly 25 years. In the past, duplications have always included the NR0B1 (nuclear receptor subfamily 0 group B, member 1, also known as DAX1) gene, a known antagonist of SF1 (Steroidogenic Factor 1) dependent SOX9 (SRY Box 9) activation and the GD was attributed to its "double gene dose". However, recent findings have questioned the neces...

Background: Steroidogenic factor 1 (encoded by the NR5A1 gene) is a transcriptional regulator of genes involved in gonadal development and steroidogenesis. Mutations in NR5A1 are associated with a wide phenotypic spectrum in 46,XY individuals ranging from partial/complete gonadal dysgenesis or anorchia, ambiguous genitalia, hypospadias, to infertility. However, little is known about the longitudinal course of endocrine markers for Sertoli and Leydig cell func...

Background: Disorders (or differences) of sex development (DSD) are rare congenital conditions in which the development of chromosomal, gonadal, or anatomical sex is atypical. The luteinizing hormone/chorionic gonadotropin receptor (LHCGR) is important for male sex development. LHCGR mutations can cause Leydig cell hypoplasia, which is an autosomal recessive disorder.Objective and hypotheses: We found two heterozygous mutations in the LHCGR, a n...

Introduction: Androgens are essential for the development of male sex characteristics. Testosterone (T) production from androstenedione (A) by the Hydroxysteroid 17-Beta Dehydrogenase 3 (HSD17B3) in gonadal Leydig cells triggers the differentiation of the Wolffian ducts into epididymis, vas deferens, seminal vesicles and the prostate. Shortly after, the virilisation of the external male genitalia starts through the conversion of T into dihydrotestosterone (DHT...

Background: Individuals born with a 45,X/46,XY karyotype can present with diverging phenotypes from normal male, Turner-like to ambiguous genitalia, the latter classically being called mixed gonadal dysgenesis. No correlation between phenotype and degree of mosaicisms in the karyotype could be ascertained so far, making clinical management of these patients difficult.Objective: To understand, if androgen action through the androgen receptor (AR) is compr...

Background: Steroidogenic factor-1 (SF-1), denominated as nuclear receptor subfamily five group A member 1 (NR5A1), is an orphan receptor that regulates several steps of adrenal and gonadal development. Mutations in its gene are responsible for different phenotypes of disorders of sex development (DSD).Objective and hypotheses: To study the functional impact of two novel NR5A1 mutations, the p.C247* and p.K396Rfs*34, both identified within the l...

Background: Recent data describe that the gonads of patients with partial gonadal dysgenesis (PGD) and mutation in the NR5A1 gene can present with a different histological pattern.Objective and hypotheses: To evaluate histological aspects of PGD caused by NR5A1 mutations.Method: Five patients with PGD, a history of gonadal biopsy or gonadectomy and confirmed mutation on NR5A1 gene were selected from a Bra...

Currently, the majority of patients with DSD do not have a molecular diagnosis. Although high throughput sequencing is having an impact on the clinical diagnosis of DSD the accurate interpretation genomic datasets of the identification of new gene mutations causing DSD is challenging. This is due to emerging evidence that DSD may be caused by mutations in many different genes and the prevalence of mutations in a single gene may be very low. As larger number of DSD patients are...