Clinical and hormonal features of selective follicle-stimulating hormone (FSH) deficiency due to FSH beta-subunit gene mutations in both sexes.

Objective To report the clinical, hormonal, and molecular features of a female adolescent with selective FSH deficiency. In addition, a complete review of previous cases is provided, focusing on hormonal aspects. Design Clinical study. Setting University hospital. Patient(s) A 16-year-old girl with primary amenorrhea and poor breast development due to isolated FSH deficiency. Intervention(s) Blood drawing before and after GnRH stimulation and pelvic ultrasound examination. Main outcome measure(s) Gonadotropin and E 2 measurements and sequencing of the FSH β-subunit gene. Result(s) The patient was referred for primary amenorrhea and partial breast development (Tanner III). Her basal and GnRH-stimulated LH levels were elevated (31 IU/L and 98 IU/L, respectively), whereas her FSH levels were undetectable ( Conclusion(s) The Tyr76X mutation of the FSH β-subunit was associated with a partial phenotype of FSH deficiency. To date, only four loss-of-function mutations of the FSH β-subunit have been described in eight patients with undetectable serum FSH and high serum LH levels. Therefore, this unusual hormonal profile strongly suggests a defect in the FSH β-subunit in both sexes.