OBJECTIVE To study the effect of the genetic factors on the occurrence and development of Alzheimer Disease (AD) and its general genetic pattern. METHODS 29 AD cases, as probands, were investigated for AD genealogical tree.The heritability of AD was estimated by Falconer method.AD genetic pattern were evaluated with Penrose’s method, the threshold value model method of Jiang San-duo. RESULTS The prevalent rate of AD in first-degree relatives was 5.06% , which was higher than that in general population.The h...