发布时间 : 星期二 文章遗传前半部分总结（英文班）更新完毕开始阅读
? Decreased intestinal absorption of phosphate ? Renal phosphate wasting
? oncogenic osteomalacia 致瘤的软骨病 ※3、遗传特征：
? More females than males
? All daughters of affected males are affected,but no sons ? A child of an affected female has 50% risk of disease 四、X-linked recessive inheritance
1、genotype：unaffected:XX XY carrier:XbY affected:XbXb XbY 2、Hemophilia 血友病
? The blood fails to clot normally
? Lacking a blood clotting factor VIII(antihemophilic globulin, AHG)bleeding from
even minor cuts
? Hemophilia B- \
? Transfusions of fresh whole blood or plasma or factor concentrates control bleeding
※3、遗传特征：
? Affects almost exclusively men
? Affected men born from carrier mother,with 50% risk of disease ? No male to male transmission ? Trait skips generations
五、Y-linked inheritance ※遗传特征
? All sons of an affected male are affected ? Affects only males
? Affected males always have affected fathers
Effect factors for single-gene disorder影响单基因遗传病分析的因素
一、 Incomplete dominance 不完全显性遗传：Incomplete dominance is a form of
intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a combined phenotype.
二、 Codominance 共显性遗传：Codominance occurs when both of the contributions of both
alleles are visible and do not over power each other in the phenotype.
三、 Delayed dominance 延迟显性：Sometimes the dominant allele expresses itself late in
development (e.g., Huntington disease), in which case the allele is said to show delayed dominance.
四、 Irregular dominance 不规则显性遗传：
? Skipped generation隔代遗传
A phenomenon of pedigrees in which a gene is transmitted from one affected person to another through a phenotypically unaffected person, as by recessivity (especially for x-linked traits), epistasis（异位显性）or absence of an environmental challenge such as a toxin.
? Penetrance 外显率
The frequency or rate of occurrence of a particular trait or disease expressed among
individuals carrying the same disease-causing gene.
五、 Expressivity 表现度：Expressivity refer to variations in a phenotype among individuals
carrying a particular genotype.
六、 Pleiotropy 基因的多效性：Pleiotropy describes the genetic effect of a single gene on
multiple phenotypic traits.
七、 Genetic heterogeneity 遗传异质性：The phenomenon that a single phenotype or genetic
disorder may be caused by any one of a multiple number of alleles or non-allele (locus) mutations.
八、 Dominance or Recessive mutation同一基因可产生显性或隐性突变
九、 Genetic anticipation 遗传早现：is a phenomenon whereby the symptoms of a
genetic disorder become apparent at an earlier age as it is passed on to the next generation.
十、 Genetic imprinting 遗传印记：Genomic imprinting is a genetic phenomenon by which
certain genes are expressed in a parent-of-origin-specific manner.
It is an inheritance process independent of the classical Mendelian inheritance.
十一、 Sex-influenced inheritance 从性遗传：Inheritance that is autosomal but has a different
intensity of expression in the two sexes, as that manifested in male pattern baldness.
These traits are determined by genes that act differently in the two sexes. The usual result is that a given trait appears preponderantly in one sex.
If a male has one recessive allele, he will show that trait, but it will take two recessive for the female to show that same trait.
十二、 Sex-limited inheritance 限性遗传：Inheritance in which a trait or phenotype is
expressed in one sex only, as in hemophilia A.
十三、 X-chromosome inactivation X染色体失活：is a process by which one of the two copies
of the X chromosome present in female mammals is inactivated.
The inactive X chromosome is silenced by packaging into transcriptionally inactive heterochromatin异染色质.
十四、 Phenocopy 拟表型：A phenocopy is an individual whose phenotype (generally referring
to a single trait), under a particular environmental condition, is identical to the one of another individual whose phenotype is determined by the genotype. In other words the phenocopy environmental condition mimics the phenotype produced by a gene.
第六章 多基因疾病的遗传
1、多基因遗传: Polygenic inheritance refers to traits that result from the influence of variation at two or more loci, with possible environmental influences also. No single \
? Combination of small effects produce (additive effect 累加效应) minor gene 微效基因 major gene 主基因
? Combination of genotypic factors and environmental factors e.g. diabetes mellitus, cancer
2、质量性状：A qualitative trait is expressed qualitatively, which means that the phenotype falls into different categories.
The pattern of inheritance for a qualitative trait is typically monogenetic. The environment has very little influence on the phenotype of these traits.
3、数量性状：A quantitative trait shows continued variation，and is the sum of several small effects caused by the gene.
If several small gene effects are present, the phenotype values for a population will typically have a normal distribution.
Examples: height, weight, cholesterol level.
4、Susceptibility（易感性）：The risks of genetically determining to diseases for individual. 5、Liability（易患性）: The probabilities of developing the disease which depend on the interaction of various genetic and environmental factors.
6、Threshold 阈值：Some proportion of individuals above a certain liability will develop the disease.
7、Heritability (遗传度）： Be a statistical definition, the proportion of phenotypic variance attributable to genetic variance.
8、多基因遗传病于单基因遗传病的区别： Monogenic disease
? Gene directly leads to disorder ? Recognizable inheritance patterns ? One gene per family ? Less common diseases
– Cystic fibrosis, muscular dystrophies
Complex disease
? Gene confers an increased risk, but does not directly cause disorder ? No clear inheritance pattern
? Involves many genes or genes and environment ? Common in population
– cancer, heart disease, dementia
第七章 群体遗传
1、群体遗传学Population genetics is a field of biology that studies the genetic composition of biological populations, and the changes in genetic structure that result from the operation of various factors, including natural selection, genetic drift, mutation and gene flow. 2、Allele Frequency 等位基因率
An allele frequency is the proportion of one allele relative to all alleles at the locus in the population (often referred to as ―gene frequency‖). 一种等位基因 / 全部的等位基因 3、Genotype Frequency 基因型率
A genotype frequency is the proportion of one genotype relative to all genotypes at a specific locus.一种基因型 / 全部基因型
一、Hardy-Weinberg Law
? The Hardy-Weinberg principle: Allele frequencies and the genotype frequency in a
population will remain the same over time (in equilibrium)
群体中的基因频率和基因型频率一代代保持不变。 if the following conditions are met. 1. Random Mating 随机婚配
2. Mutation can be ignored 没有突变 3. No natural selection 没有自然选择 4. No genetic migration 没有基因迁移
5. Genetic Drift and genetic flow are negligible没有基因漂变和基因流 If the frequency of the dominant allele A （显性等位基因）in the founding population was p , and the frequency of the recessive allele a （隐形等位基因）was q, then after one generation of random mating the genotype frequencies would remain fixed and would be in the ratio:
p+q = 1
p2 + 2pq + q2 = 1
二、Factors causing genotype frequency changes影响遗传平衡的因素 Non-random Mating 非随机婚配 Selection 选择 Mutation 变异
Random Drift 基因漂变 Gene flow 基因流 （一）非随机婚配：
1、Assortative mating (选型婚配）：positive assortative mating（阳性选型婚配）negative assortative mating
2、Consanguinous mating （近亲婚配）：有共同祖先血缘关系的亲属之间的婚配。
? coefficient of relationship (亲缘系数，r ）is the probability that at a random locus,
the alleles there will be identical by descent.近亲的程度。
? Inbreeding coefficient (近婚系数，F) is the probability that two alleles at a randomly
chosen locus are identical by descent.子女得到一对相同基因的概率。 ? Coefficient of relationship (亲缘系数，r ）
Parent-child（双亲-子女） first 1/2 Siblings （同胞） first 1/2 Uncle-niece （叔-侄） second 1/4 first cousins （堂亲） third 1/8 3、Inbreeding coefficient （近婚系数）of Autosomal inheritance（常染色体遗传） 一级亲属间的近婚系数为1/4 二级亲属间的近婚系数为1/8 三级亲属间的近婚系数为1/16 4、X-linked inheritance
因为女性有两条X染色体，所以可以形成纯合子，会受到近亲婚配的影响。男性为半合子（hemizygote)，近亲婚配不受影响。
计算X连锁基因的F值时，只计算女性F值。 传递特点：男性的X连锁基因一定传给女儿，传递概率为1 男性的X连锁基因不可能传给儿子，传递概率为0