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1、（摘自 45 度角 F3 http:/www.cc98.org/dispbbs.asp?BoardID=241 in other words. The recurrence risk is one in four for each birth. The parents of affected child may be consanguineous. Males and females are equally likely to be affected. There are many small groups in which the frequency of certain rare rece
2、ssive genes is quite different from that in the general population.X-linked Recessive- The trait is passed from an affected man through all his daughters to, on the average, half their sons. The incidence of the trait is much higher in males than in females. The trait is never transmitted directly f
3、rom father to son. The trait may be transmitted through a series of carrier females; if so, the affected males in a kindred are related to one another through females. Carriers show variable expression of the trait. X-linked dominant inheritance Affected males have no normal daughters and no affecte
4、d sons. Affected heterozygous females transmit the condition to half their children of either sex. Affected females are more common than affected males, but as they are almost always heterozygotes they usually have milder (but Variable) expression. Y-linked Disordersthey are always passed from fathe
5、r to son, and they never appear in females Chapter 5 多基因病 Qualitative trait (discrete trait): A genetic disease trait that either present or absent Monogenic disease, Blood types Quantitative trait (continued variation ): are measurable characteristics such as height, blood pressure, serum cholester
6、ol, and body mass index Characteristics of Inheritance of Complex Diseases Not single-gene disorders and do not demonstrate a simple Mendelian pattern of inheritance Demonstrate familial aggregation, because relatives of an affected individual are not likely to have disease-predisposing alleles in c
7、ommon with the affected person than are unrelated individuals Pairs of relatives who share disease-predisposing（疾病倾向的）genotypes at relevant（相关）loci may still be discordant（不一致）for phenotype (show lack of penetrance) because of the crucial(至关紧要的) role of nongenetic factors in disease causation(原因). T
8、he most extreme examples of lack of penetrance despite identical genotypes are discordant monozygotic twins (MZ) The disease is more common among the close relatives of the proband and becomes less common in relatives who are less closely related. Greater concordance for disease is expected among MZ
9、 versus dizygotic twins (DZ) Linkage Analysis is more difficult in multifactoral conditions than in single-gene disorders:A,Variants in more than 1 gene are likely to contribute to the disorderB,The number of affected persons within a family is likely to be fewer than for a single-gene disordersC,Th
10、e mode of inheritance is usually uncertainD,Some multifactorial disorders are likely to have more than 1 etiology(病因，病源)E,Many multifactorial conditions have a late age of onsetChapter 6 群体遗传学Mendelian populationAn interbreeding population of sexually reproducing individuals sharing a common gene po
11、ol. Gene pool : the genetic constitution of a population of a given organism.(All the genes of all the individuals in population make up the gene pool.) Genotypes: the genetic constitution of a single individual. Gene frequency (allelic frequency): the frequencies of the members of a pair of allele
12、genes in a population. Phenotype frequencyHardy Weinberg EquilibriumStates the relationships between the frequency of alleles at a locus, and the genotypes resulting from these alleles.Hardy-Weinberg equilibrium implies that gene and genotype frequencies are constant from generation to generation. I
13、f disequilibrium occurs, equilibrium will be reestablished after one generation of random mating. H-W law rests on several assumptions:1. large population2. random mating3. no mutations4. no migration between populations 5. no selection - all genotypes reproduce with equal success Exceptions to Hard
14、y Weinberg AssumptionsA Migration introduction / loss of allelesB Mutations may occur at different frequency in different populationsC Small population size- genetic isolate / founder effectD Non-random mating 1- consanguinity 2-assortative mating(=non-random mating)Hardy-Weinberg equilibrium lawIf
15、two alleles at a gene - A and a 1. frequency of the A allele = p 2. frequency of the a allele = q3. The two fractions add up to totality p + q = l 4. the proportions of the three genotypes: AA, Aa and aa are p2: 2pq : q25. Hardy-Weinberg formula: p2 (AA) + 2pq (Aa) + q2 (aa) = 1Changes in Allele Fre
16、quency Can be caused by: mutation (source of genetic variation) selection (phenotypes differ in biological fitness)(deleterious mutations may be removed by early death / lack of reproduction) migration (movement in or out) F(Fitness) - the ability to contribute to the gene pool of the next generatio
17、nS(selective coefficient)Heterozygote Advantage eg. Sickle cell anemia. Mutant allele has a high frequency despite reduced fitness in affected individuals. Heterozygote has increased fitness over both homozygous genotypes Genetic DriftFluctuation in allele frequency due to chance in a small populati
18、on.Founder Effect if an original member of a sub-population has a rare allele, it may become common in the sub-population (high carrier frequency), resulting in high frequency of rare disease.Consanguinity/Inbreeding when an individuals parents have one or more common ancestors, identifiable from a
19、pedigree (or archival records)- because of genetic isolate, cultural practice, assortative mating-Increased likelihood of q 2Chapter 7 线粒体基因遗传 Mitochondrial genome+Small (16.5 kb) circular DNA +1 gene/0.45 kb +Very few repeats+Heavy and Light strands +No introns +93% coding Special features of mitoc
20、hondrial genetics +Maternal Inhertance +Heteroplasmy +Replicative Segregation +Threshold Expression +High Mutation RateHomoplasmy originally, it studies the effect exerted on drug ADMET (absorption, distribution, metabolism, excretion, & toxicity) process by the human cytochrome family proteins. Pha
21、rmacogenomics is the extension and enhancement of the Pharmacogenetics studies in the molecular sequence context of the individual genetic structures of the whole genome.Chapter 11 肿瘤遗传Cancer is a disease of genes gone awry. Genes that control the orderly replication of cells become damaged, allowin
22、g the cell to reproduce without restraint and eventually to spread into neighboring tissues and set up growths throughout the body. Proto-oncogenea class of normal cellular protein-coding genes that promote growth and survival of cells.Gatekeeper TSGs control cell growth.Caretaker TSGs protect the i
23、ntegrity of the genome.1.All cancer is genetic2.Cancer usually arises in a single cell3.Tumor can be classified as benign and malignantNeoplasia: A group of diseases characterized by uncontrolled cell proliferation leading to a mass or tumor (neoplasm).Cancer: A malignant tumor that is capable of in
24、vading or spreading (metastasizing) or both. ( sarcoma: mesenchymal tissues carcinoma: epithelial tissues leukemia/lymphoma: hematopoietic/lymphatic)Apoptosis（凋亡）(Programmed cell death,PCD): A normal process of DNA fragmentation and cellular suicide. Oncogenes are genes that are associated with the
25、development of cancers These genes are often bad alterations of normal genes that are concerned with normal cell identity, cell growth, and cell division during embryogenesis included Viral oncogenes and cellular oncogenesv-oncare named “V-whatever“ when they were identified in virusesc-oncThe normal versions of key developmental control genes are called celluler oncogenes.