医学遗传与胚胎发育 Chapter 1 绪论

1、Medical Genetics and Embryonic Development医学遗传与胚胎发育1课程简介“医学遗传与胚胎发育”是一门由医学遗传、胚胎发育及分子生物学所组成的整合课程。该课程力图从群体、家系、个体、细胞和分子水平阐释人类遗传性疾病的遗传规律、分子基础及发病机制，为遗传病的诊断、治疗和预防提供理论依据。 2课程内容医学遗传与胚胎发育基础：包括人类基因组学；遗传信息流（包括DNA的复制、转录、翻译和调控）；胚胎早期发育。医学遗传学原理：人类染色体；单基因遗传；多基因遗传；群体遗传；表观遗传人类遗传性疾病：染色体病；单基因遗传病（生化遗传病）；多基因遗传病；线粒体基因病；体细胞

2、遗传病（肿瘤）。遗传病诊治：临床遗传3课程成绩由平时成绩与期末考试成绩组成。平时成绩占30%，包括染色体核型分析及PBL案例讨论等；期末考试成绩占70%，用全英语出题，中文或英文答题。4使用教材医学遗传与胚胎发育 (第2版讲义)陈竺 主编.医学遗传学（第2/3版），人民卫生出版社，2010；成令忠、王一飞、钟翠平 主编.组织胚胎学人体发育和功能组织学，主编，上海科学技术文献出版社，2003；查锡良、药立波主编生物化学与分子生物学第8版, 人民卫生出版社，2013。5参考书目孙开来 主编，人类发育与遗传学（第一版），科学出版社出版，2004；Turnpenny P, Ellard S. Emer

3、ys Elements of Medical Genetics. 14th ed., 2012Nussbaum RL, McInnes RR, and Willard HF. Thompson and Thompsons genetics in medicine. 7th ed., 2007Nelson DL and Cox MM. Lehninger Principles of Biochemistry. 4th ed., 2004Sadler TW, Langman J. Langmans Medical Embryology. 10th ed., Lippincott Williams

4、& Wilkins, 2006Allis CD. Epigenetics. Cold Spring Harbor Laboratory Press, 2007.6参考网址http:/ (整合课程网站，请先登录)/jpkc (国家级精品课程组织胚胎学，上海市精品课程医学遗传学、生物化学网站)； (人类孟德尔遗传网站)http:/www.hgmd.cf.ac.uk/ac/index.php (人类基因突变资料库网站)/index.html (欧洲生物信息学网站)/(美国人类基因组研究所网站)7Medical GeneticsMedical genetics is the science of hu

5、man biologic variation as it relates to health and disease.8All medicine is genetics - Mckusick VA.Father of Genetic Medicine Medicine in future is molecular genetics - Dulbecco RFeb. 22, 1914 Feb. 19, 2012 Advocator of Human Genome Project9 Why Molecular Biology?Molecular biology: the study of gene

6、 structure and function at the molecular level to understand the molecular basis of hereditary, genetic variation, and the expression patterns of genes.The molecular biology field overlaps with other areas, particularly genetics and biochemistry. 10 Why Embryology（胚胎学）?Birth defects mainly occurred

7、at embryongic period.Birth defects are the leading cause of infant mortality (死亡率).Birth defects are a major contributor to morbidity(发病率), including physical and mental handicaps.All women of childbearing age are at risk of having an infant with a birth defect. The incidence rate (发生率) is 6/100 bir

8、ths.111st Prenatal Visit: 8 Weeks1213Human Variation and Heredity we are all 99.9% the same, DNA-wise! differ at about 1 in every 1,200 to 1,500 bp, or letters 14GeneticsBiological genetic variation Plant Genetics Microbiological Genetics Animal Genetics Human Genetics: Medical Genetics 15Chapter 1

9、Genetics in MedicineGENETIC BASIS OF HEALTH AND DISEASES BRIEF HISTORY OF MEDICAL GENETICSHUMAN GENOMICSCLASSIFICATION OF GENETIC DISEASES CONGENITAL, FAMILIAL AND GENETIC DISORDERSTASKS AND PERSPECTIVES OF MEDICAL GENETICS AND GENETIC MEDICINE 16GENETIC BASIS OF HEALTH AND DISEASESHEALTH: Human bei

10、ng depends on a balance of the genetically regulated metabolism and the changing environmental conditions. WHO about HEALTHDISORDERS: Defects in genetic information embedded in the DNA sequence of the genome and/or profound changes of the environment disrupt this balance and lead to diseases. 17Gene

11、tic disorders: the disorders are caused by deficiency of genetic structure, they can be present at birth or manifest themselves late in life. They are usually familial but may be sporadic.(坏血病)(幽门狭窄)(脊柱裂)(苯丙酮尿症, 半乳糖血症)18BRIEF HISTORY OF MEDICAL GENETICSEarly Knowledge About Hereditary DiseasesHippoc

12、rates(希波克拉底): diseases to be transmissible through family pedigree Hebraisms Code(希伯来法典): forbidding the circumcision (包皮环切/割礼). Maupertuis: describing polydactyly, albinism Baedeker(1859): Diagnosis of alkaptonuria Mendel law(1822-1884): to be continued19Gregor Mendel (1822-1884) was the founder of

13、 modern geneticsMendel first discovered the principles of heredity by crossing different varieties of pea plants and analyzing the pattern of transmission of traits in subsequent generations. The first law (or law of segregation) of Mendel. The second law (or law of independent assortment) of Mendel

14、.20History of Medical Genetics YearDiscoveryAuthors1900Rediscover Mendels law of inheritance De Varies, et al 1901Discovery of the human ABO blood groups Landsteine 1905Brachydactyly (short fingers) Farabee 1908Inborn errors of metabolism Garrod 1908Showing that gene and genotypic frequencies remain

15、 stable Hardy and Weinberg 1909Gene for the unit of inheritance Johanssen 1910 Law of linkage and law of crossing-over Morgan 1927Gene mutations can be induced by X rays Muller1930Establishing the principles of population genetics Fisher, et al1944DNA is the genetic material Avery 1953Discovery of D

16、NA double helix structure Watson, Crick 21YearDiscoveryAuthors1961Evidence of denaturation of DNA Marmur, et al. 1966Demonstration of DNA genetic codon Nirenberg, et al. 1970First synthesis of gene in the test tube Khorana 1975Detection of specific DNA sequence using gelSouthern transfer and hybridi

17、zationSouthern1975Rapid DNA sequencing Sanger 1977First cloning of human gene Shine1978First application of RFLP and DNA diagnosis Kan 1981Sequencing of the first human mitochondrion Anderson 1985First demonstration of DNA “finger printing” Jeffreys 1985Invention of the polymerase chain reaction (PC

18、R) Mullis, et al.1990First clinical gene therapy for ADAAnderson 1991Launch of 15 year plan of Human genome project Watson, et al. 2004Completed human genome sequence covering 99% IHGSC 22HGP23Chapter 1 Genetics in MedicineGENETIC BASIS OF HEALTH AND DISEASES BRIEF HISTORY OF MEDICAL GENETICSHUMAN G

19、ENOMICSCLASSIFICATION OF GENETIC DISEASES CONGENITAL, FAMILIAL AND GENETIC DISORDERSTASKS AND PERSPECTIVES OF MEDICAL GENETICS AND GENETIC MEDICINE 24Human GenomicsOverviewHuman Genome ProjectFunctional GenomicsGenomics and Human Health25From Chromosome to DNA262728Goals of the HGP Identify all the

20、approximately 20,00025,000 genes in Human DNA.Determine the sequences of the 3 billion chemical base pairs that make up human DNA.Store this information in databases.Improve tools for data analysis.Transfer related technologies to the private sector.Address the ethical, legal, and social issues(ELSI

21、) that may arise from the project.29The international Human Genome Sequencing ConsortiumIncluded hundreds of scientists at 20 sequencing centers in 6 countries: -China 1% -France 2.8% -Germany 2.2% -Great Britain 33% -Japan 7% -United States 54% NIH and DOE3031Four MapsCytogenetic mapLinkage mapPhys

22、ical mapSequence map32Genetic mapGenetic map = Treasure map of genomeLinkage map: By calculating the linkage between genetic markers of the recombination frequency, to determine their relative distance (1cM) Genetic markers: RFLP, MS and SNPLinkage analysis33Physical Map Physical map: A map determin

23、ing physical distance between genetic markers. 1cM1MbSequence tagged site, STSExpressed sequence tag, EST Yeast artificial chromosome, YAC; Bacterial artificial chromosome, BAC; P1 artificial chromosome clones, PACs34Two methods for sequencing the human genome35Template and Sequencing Room36Standard

24、 of Complete sequenceError rate of less than 1 / 10 000Sequence is consistent, that is, there is no gapSequence can be used to faithfully represent the cloning of the genome structure 37Human Genome Project Goals and Completion Dates (2003)AreaGoalAchievedDate AchievedGenetic Map 2- to 5-cM resoluti

25、on map (600 1,500 markers)1-cM resolution map (3,000 markers) September 1994Physical Map30,000 STSs 52,000 STSs October 1998DNA Sequence 95% of gene-containing part of human sequence finished to 99.99% accuracy99% of gene-containing part of human sequence finished to 99.99% accuracy April 2003Capaci

26、ty & Cost of Finished SequenceSequence 500 Mb/year at 1,400Mb/year at 50 bp) and can be assayed by SNP microarrays or array comparative genomic hybridization. Large chromosomal aberrations are rarer, large, and microscopically visible after G-banding and are often associated with major congenital ab

27、normalities (e.g., Down syndrome associated with trisomy 21).single nucleotide polymorphisms(CNV)MS, microsatellite; small deletion; small insertionSubmicroscopicMicroscopically visible (3Mb)gross deletion; gross insertion51Studies on DNA sequence of human genome variationSNP：3 10 million52The tool

28、to solve complex traits in humans?Yes. Genome-wide associate study (GWAS).53ProteomicsProteomics is the large-scale study of proteins, particularly their structures and functions. mRNA tells you what might happen.Proteome tells you what is happening.54Model organismTechnical difficultyComplexityDros

29、ophilazebrafishmousehumanC. elegansyeastIn particular, model organisms are widely used to explore potential causes and treatments for human disease when human experimentation would be unfeasible or unethical. 55Gene of InterestGain of Function Loss of FunctionGenetically-Modified Mouse Models56Knock

30、-out (基因敲除)Knock-in (基因敲入)Knock-down (基因敲减) Transgenic mice (转基因小鼠)Model organism 57S. wt S. +/- S. tumor 1.7KbPLAG1Wt Tg Tu18S4.5K18SIGF-IIPLAG1 transgenic mice58w.t. +/- -/-Rig-K knockout miceA B CD E F59Fgf9wt/wt Fgf9wt/S99N Fgf9wt/S99Nwt+/-+/-Abnormalities in tooth and tail development in Fgf9wt

31、/S99N miceFgf9wt/wt Fgf9wt/S99N Fgf9wt/S99N60Mario R. CapecchiSir Martin J. EvansOliver SmithiesUniversity of Utah; Howard Hughes Medical Institute, Salt Lake City, UT, USACardiff University Cardiff, United KingdomUniversity of North Carolina at Chapel Hill, NC, USAUSA b. 1937 (in Italy)UKb. 1941USA

32、 b. 1925 (in UK)The Nobel Prize in Physiology or Medicine 2007for their discoveries of principles for introducing specific gene modifications in mice by the use of embryonic stem cells61Collins, FS, et al. A vision for the future of genomics research. Nature, 2003, 422: 835-4762Paradigm shifts in bi

33、omedical researchStructural genomicsFunctional genomicsGenomicsProteomicsMap-based gene discoverySequence-based gene discoveryMonogenic disordersMultifactorial disordersSpecific DNA diagnosisMonitoring of susceptibilityAnalysis of one geneAnalysis of multiple genes in families, pathways or systemsGe

34、ne functionGene regulationEtiology (specific mutation )Pathogenesis (mechanism)One speciesSeveral species63New ProjectsInternational HapMap ProjectEncyclopedia of DNA Elements, ENCODE Human Proteome Project, HPP Human Epigenome Project, HEPThe Cancer Genome Atlas, TCGA 3D Nucleome Project, 3DN64沿着DN

35、A双轨“淘金”、致富。65Chapter 1 Genetics in MedicineGENETIC BASIS OF HEALTH AND DISEASES BRIEF HISTORY OF MEDICAL GENETICSHUMAN GENOMICSCLASSIFICATION OF GENETIC DISEASES CONGENITAL, FAMILIAL AND GENETIC DISORDERSTASKS AND PERSPECTIVES OF MEDICAL GENETICS AND GENETIC MEDICINE 66Classification of Genetic diso

36、rdersFive groups of genetic disordersChromosome disorders Monogenic (single-gene) disorders Disorders with multifactorial inheritance (polygenic disorders)Mitochondrial genetic disordersSomatic cell genetic disorders67Chromosome disordersThe disorders are caused by numerical or structural chromosome

37、 aberration.Autosome disorders Down syndrome 47, XX(XY), +2168Genosome disorders Turner syndrome 45, XOChromosome disorders69Single-gene disordersDisorders are caused by single-gene mutationAutosomal dominant inheritance (AD)Congenital clavicula imperfecta (先天性锁骨发育不全)70DwarfismSingle-gene disorders7

38、1Albinism (AR)Single-gene disorders72X-linked Dominant inheritance (XD)Hypophosphatemic rickets (Vitamin D-resistant rickets)(低磷酸盐血症/抗维生素D佝偻病)Single-gene disorders73Single-gene disordersHemophilia (XR) “Royal Disease” 7475 OMIM Statistics for March 28, 2015TypeAuto-somalX-linkedY-linkedMitochon-dria

39、lTotalGene description14091692483514866Gene and phenotype, combined8420288Phenotype description, molecular basis known40702914284393Phenotype description or locus, molecular basis unknown1530130501665Other, mainly phenotypes with suspected mendelian basis1720113201835Total214951228596522847/statisti

40、cs/entry76Chr. No.CountChr. No.CountChr. No.Count115119581178822967105601822738291194619957459512811203935695132872116169001450122358772215455X825854416622Y53OMIM Synopsis of the Human Gene Map (Updated March 28th, 2015)Number of phenotypes for which the molecular basis is known5,442 Number of genes

41、 with phenotype-causing mutation3,363 77OMIM #612961 MULTIPLE SYNOSTOSES SYNDROME 3; SYNS3. Gene map locus 13q11-q12TEXT A number sign (#) is used with this entry because this form of multiple synostoses syndrome is caused by mutation in the fibroblast growth factor-9 gene (FGF9; 600921).For a gener

42、al phenotypic description and discussion of genetic heterogeneity in multiple synostoses syndromes, see SYNS1 (186500).CLINICAL FEATURES Wu et al. (2009) described 12 affected individuals from a 5-generation Chinese family segregating autosomal dominant multiple synostoses syndrome, with fusions of

43、proximal interphalangeal, carpal-tarsal, and humeroradial joints. Hearing, stature, and intelligence were normal in all affected individuals. Only mild semidislocation or cubital valgus at elbow joints or limitation of finger joint flexion was found in 4 patients aged 11 years or below, suggesting t

44、hat the phenotype is age dependent. MAPPING Wu et al. (2009) performed linkage analysis in a 5-generation Chinese family segregating autosomal dominant multiple synostoses syndrome, but found no linkage to known loci on chromosomes 17q22 and 20q11.2. A genomewide screen identified a single locus on

45、chromosome 13q11-q12 that cosegregated with the disease (maximum 2-point lod score of 3.7 at D12S1236). Fine mapping and haplotype analysis narrowed the critical interval to 8.6 Mb between D13S175 and D13S221, a region containing 22 candidate genes. MOLECULAR GENETICS In a 5-generation Chinese famil

46、y with autosomal dominant multiple synostoses syndrome mapping to chromosome 13q11-q12, Wu et al. (2009) identified a heterozygous missense mutation in the candidate FGF9 gene (600921.0001) that segregated with disease and was not found in 250 unrelated ethnically matched controls. REFERENCES 1. Wu,

47、 X.; Gu, M.; Huang, L.; Liu, X.; Zhang, H.; Ding, X.; Xu, J.; Cui, B.; Wang, L.; Lu, S; Chen, X.; Zhang, H.; Huang, W.; Yuan, W.; Yang, J.; Gu, Q.; Fei, J.; Chen, Z.; Yuan, Z.; Wang, Z. : Multiple synostoses syndrome is due to a missense mutation in exon 2 of FGF9 gene. Am. J. Hum. Genet. 85: 53-63,

48、 2009. 78OMIM #615025 CHARCOT-MARIE-TOOTH DISEASE, AXONAL, TYPE 2Q; CMT2QTEXT: A number sign (#) is used with this entry because of evidence that Charcot-Marie-Tooth disease type 2Q (CMT2Q) is caused by a heterozygous loss-of-function mutation in the DHTKD1 gene (614984) on chromosome 10p14. Compoun

49、d heterozygous mutation in this gene results in 2-aminoadipic 2-oxoadipic aciduria (204750).For a phenotypic description and a discussion of genetic heterogeneity of axonal CMT, see CMT2A1.Clinical Features: Xu et al. (2012) reported a 5-generation Chinese family from the Shandong Province of China

50、affected by an autosomal dominant form of CMT2. This family was ascertained through a 40-year-old male proband. There were 8 affected individuals, 5 males and 3 females, among 5 generations who had symmetrical muscle wasting and a predominating weakness of the distal parts of the lower limbs, decrea

51、sed or absent deep tendon reflex, and mild to moderate deep sensory impairment. The initial complaints of the proband included difficulty walking and tripping due to foot and distal leg weakness at the age of 15 years. Neurologic exam at that time revealed muscle atrophy in the distal parts of the f

52、orearms and inner osseous muscles of the hands. The lower legs developed severe muscle atrophy, which presented as crane-leg-like malformations. Motor neuron and sensory neuron conduction velocities were normal in the upper limbs but reduced in the lower limbs. Muscle biopsy from the proband showed

53、small angulated muscle fibers, and electron microscopy showed sarcomere disappearance, disorganized microfilaments, and mitochondrial vacuolization. Among the other individuals who were examined, ranging in age from 13 to 71 years, all had symptom onset between ages 13 to 25 years. All exhibited pes

54、 cavus and had some degree of motor and sensory deficits, more severe in lower than in upper extremities.Mapping: Xu et al. (2012) performed linkage analysis in a Chinese family segregating axonal CMT and found that the phenotype was linked to chromosome 10p14-p13, spanning a 5.41-Mb region between

55、D10S585 and D10S1477.Molecular Genetics: In all 8 affected members of a Chinese family segregating axonal CMT, Xu et al. (2012) identified a heterozygous nonsense mutation (Y485X; 614984.0004) in the DHTKD1 gene. The mutation was not found in unaffected individuals in the family or in 250 unrelated

56、control individuals. Knockdown of DHTKD1 resulted in decreased ATP, total NAD(+), and NADH, and NADH in vitro.REFERENCES: 1. Xu, W., Gu, M., Sun, L., Guo, W., Zhu, H., Ma, J., Yuan, W., Kuang, Y., Ji, B., Wu, X., Chen, Y., Zhang, H., Sun, F., Huang, W., Huang, L., Chen, S., Wang, Z. A nonsense mutation in DHTKD1 causes Charcot-Marie-Tooth disease type 2 in a large Chinese pedigree. Am. J. Hum. Genet. 91: 1088-1094, 2012.7980%的罕见病为遗传病，估计共有60007000种每年2月的最后一天为国际罕见病日80Multifactorial disordersDisorders are caused b