Serum BDNF was also significantly reduced in females compared with males in severe AD (mini-mental state examination, MMSE, score under 20—females, n = 31, 11.25 ± 2.76 pg/mL; males, n = 13, 12.60 ± 1.65 pg/mL p = 0.049). The gene discussed is BDNF; the disease is Alzheimer disease.