Case Report: Longitudinal follow-up and testicular sperm extraction in a patient with a pathogenic NR5A1 (SF-1) frameshift variant: p.(Phe70Ser fs*5)

Abstract

Background: Steroidogenic factor 1 (SF-1), encoded by the nuclear receptor subfamily 5 group A member 1 (NR5A1) gene, is a transcriptional factor crucial for adrenal and gonadal organogenesis. Pathogenic variants of NR5A1 are responsible for a wide spectrum of phenotypes with autosomal dominant inheritance including disorders of sex development and oligospermia-azoospermia in 46,XY adults. Preservation of fertility remains challenging in these patients.

Objective: The aim was to offer fertility preservation at the end of puberty in an NR5A1 mutated patient.

Case report: The patient was born of non-consanguineous parents, with a disorder of sex development, a small genital bud, perineal hypospadias, and gonads in the left labioscrotal fold and the right inguinal region. Neither uterus nor vagina was detected. The karyotype was 46,XY. Anti-Müllerian hormone (AMH) and testosterone levels were low, indicating testicular dysgenesis. The child was raised as a boy. At 9 years old, he presented with precocious puberty treated by triptorelin. At puberty, follicle-stimulating hormone (FSH), luteinising hormone (LH), and testosterone levels increased, whereas AMH, inhibin B, and testicular volume were low, suggesting an impaired Sertoli cell function and a partially preserved Leydig cell function. A genetic study performed at almost 15 years old identified the new frameshift variant NM_004959.5: c.207del p.(Phe70Serfs*5) at a heterozygous state. He was thus addressed for fertility preservation. No sperm cells could be retrieved from three semen collections between the ages of 16 years 4 months and 16 years 10 months. A conventional bilateral testicular biopsy and testicular sperm extraction were performed at 17 years 10 months of age, but no sperm cells were found. Histological analysis revealed an aspect of mosaicism with seminiferous tubules that were either atrophic, with Sertoli cells only, or presenting an arrest of spermatogenesis at the spermatocyte stage.

Conclusion: We report a case with a new NR5A1 variant. The fertility preservation protocol proposed at the end of puberty did not allow any sperm retrieval for future parenthood.

Keywords: azoospermia; congenital; disorder of sex development; gonadal dysgenesis; hypospadias; male infertility; spermatogenesis; testicular sperm extraction.

Figure 1

Testicular biopsy shows severely impaired spermatogenesis with an aspect of histological mosaicism. The seminiferous tubules were of overall reduced diameter (decreased by approximately 30%–50% compared to physiological adult pubertal seminiferous tubules of 150–250 µm in diameter) and lined by a thickened basal membrane. The seminiferous tubules were either atrophic (*), with Sertoli cells only (**), or presenting spermatogenesis arrest at the spermatocyte stage (•). The interstitial tissue was fibro-edematous with numerous Leydig cells (‡) (hematoxylin–eosin–saffron). Thick black arrow indicates Sertoli cells, thin black arrow indicates spermatocyte, and solid black triangle indicates spermatogonia. Biopsy fragments were fixed in alcohol, formalin, and acetic acid (AFA) and paraffin-embedded. Sections of 3 μm were stained by hematoxylin–phloxin–saffron. Slide evaluation was performed on a Leica DM2500 microscope. Two different scales: 300 µm (A) and 200 µm (B).

Figure 2

Identification of the NR5A1 variant using Sanger sequencing. Variation was identified using reference NM_004959.5 for NR5A1 transcript on GRCh37/hg19 human genome assembly, NP_004950.2 for SF-1 protein. The screenshot comes from SeqScape 3 software. The nucleotide reference sequence is highlighted in blue. This variant was classified as pathogenic according to the ACMG criteria (PVS1, PM1, and PM2). The polymorphism NM_004959.5: c.437G>C p.(Gly146Ala) was not found. In ACMG criteria: PM, pathogenic moderate; PVS, pathogenic very strong. “PVS1: null variant (non-sense, frameshift, canonical ±1 or 2 splice sites, initiation codon, single or multi-exon deletion) in a gene where loss of function is a known mechanism of disease.” “PM1: located in a mutational hot spot and/or critical and well-established functional domain (e.g. active site of an enzyme) without benign variation.” “PM2: absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes or ExAC.”.