Endocrine Abstracts

Introduction: Mutations in FSHβ gene leading to isolated follicle-stimulating hormone (FSH) deficiency are very rare and the disorder is inherited in an autosomal recessive manner. Up to date, only few case reports have been described in the literature.

Case report: 25-years old woman was admitted to the Endocrinology Department with a suspicion of FSH deficiency. She was firstly diagnosed with primary amenorrhoea and impaired pubertal development at the age of 17. Hormonal tests were performed and low concentrations of FSH and estradiol were found. Pelvic ultrasound and pituitary MRI did not reveal any pathology. Treatment with hormonal replacement therapy was started and continued for 8 years. It was withdrawn 7 days before admission to our department. During hospitalization hormonal function tests were performed and there were found undetectable concentrations of FSH and estradiol, while LH level was mildly elevated. In the gonadotropin-releasing hormone stimulation test there was no response in FSH concentration. Anti-Mullerian hormone (AMH) concentration was within the normal range and inhibin B level was undetectable low. Next-generation sequencing was performed and homozygotic mutation in FSHB gene was found (ENST00000417547c.236-237delTG, protein p.Val79fs). Isolated FSH deficiency was diagnosed.

Conclusion: Hypogonadism and primary amenorrhoea may present a clinical picture of isolated FSH deficiency in women. However, it is worth to notice that a severe deficiency of FSH was not related with AMH deficiency. Patients with isolated deficiency of single gonadotropin give us a new, important insight into its role in human fertility processes, which are still under investigation.