The FSHB gene controls the production of follicle stimulating hormone subunit beta (FSHB) in the brain (pituitary gland) which, in combination with T, drives sperm production and development in the Sertoli cells of the testicles. Healthy males produce approximately 120 million sperm daily. Anything below 15 million sperm/ml of semen is considered low. Population studies have shown that 30-40% of infertility in couples is due to the male.
The T result of the reported variant (-211GT) has been linked to low FSH levels which in turn is associated with reduced sperm production and poor fertility.
Other factors that negatively affect sperm production include reduced blood and oxygen flow to the testes (e.g. tight underwear, saunas, cycling), alcohol and drug abuse, exposure to toxic chemicals, heavy metals, radiation or x-rays, prolonged physical and emotional stress, poor sleep, obesity and low levels of vitamins A, B-complex, D, and zinc.