二、多基因遗传一些常见的畸形或疾病,其发病率大多超过1/1,000,这些病的发病有一定遗传基础,所以,常表现有家族倾向。但是,它们的遗传基础不是单基因,所以,患者同胞中的发病率不是1/2或1/4,远比这个频率为低,大约只有1～10％。过去,临床医生常常认为,这些病的发病有遗传素质或某种体质。近年来的研究工作表明,这些病有许多是有多基因遗传基础的。 (一)多基因遗传的特点前面讲的单基因遗传的遗传性状属于质量性状,它们虽有变异,但是,在一个群体中观察,可以明确 Second, polygenic inheritance Some common deformities or diseases, the incidence of mostly more than 1 / 1,000, the incidence of these diseases have some genetic basis, therefore, often have a family tendency. However, their genetic basis is not single gene, so the incidence in patients with siblings is not 1/2 or 1/4, much lower than this frequency, only about 1 to 10%. In the past, clinicians often think that the incidence of these diseases genetic or physical fitness. Recent research shows that many of these diseases are genetically multi-genetically based. (A) of the characteristics of polygenic inheritance The genetic traits described in front of single-gene inheritance of quality traits, although they have variation, but observed in a group can be clear