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

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.