Our finding of increased platelet MAO-B activity in veterans with PTSD compared with veterans without PTSD, in both smokers and non-smokers, is in line with previous findings obtained in much smaller groups [38], which included 103 war veterans with PTSD, subdivided into those with (N = 25) or without (N = 78) psychotic features; 41 combat exposed veterans without PTSD; and 242 healthy control male subjects [38]. The gene discussed is MAOB; the disease is post-traumatic stress disorder.