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很多常见病在许多群体中发病率大于1%,这些病从双生子及家系研究中已确认是遗传的,但遗传缺陷的特性一直未能搞清。这些病包括糖尿病、高血压、冠状动脉病、癫痫、Alzheimer型痴呆,主要的精神性疾病有躁狂-抑郁症(双相型)和精神分裂症。这些病的遗传曾认为是非孟德尔式遗传,即在家系中不能简单分为隐性或显性遗传性状,通常认为是多基因遗传,即易患性是由许多基因的积累作用,没有任何单一基因本身能明显影响这些病的易感性。然而,单基因在这些病的一些病例中占有一定的比例,包括胰岛素依赖性糖尿病和21号染色体连锁的Alzheimer型痴呆与特定染色体区域的基因连锁和关联
Many common diseases have a prevalence of> 1% in many groups and these have been identified as inherited from twins and pedigree studies, but the nature of genetic defects has not been elucidated. These include diabetes mellitus, hypertension, coronary artery disease, epilepsy, Alzheimer’s dementia, and major psychiatric disorders manic-depressive (bipolar) and schizophrenia. The inheritance of these diseases was considered non-Mendelian inheritance, that is, can not be simply divided into recessive or dominant genetic traits in the family, is generally considered to be polygenic, that is susceptibility is caused by the accumulation of many genes, there is no single The genes themselves can significantly affect the susceptibility of these diseases. However, monogenic genes account for a proportion of these cases in some cases, including insulin-dependent diabetes and Alzheimer’s dementia linked to chromosome 21 linked and linked to genes in specific chromosomal regions