Although pleiotropy had been suggested to be common to the genetic architecture of complex disease [72], only isolated cases of pleiotropy had been reported previously such as the links between APOE genotypes and dyslipidemia, coronary heart disease and Alzheimer's disease [73], and type 2 diabetes and prostate cancer (TCF2 genotypes) [74]. The gene discussed is HNF1B; the disease is early-onset autosomal dominant Alzheimer disease.