医学专业英语课件_15.ppt

Making babies:Genetically CorrectZhi Hua RanThe department of Gastroenterology Ren Ji Hospital2021/9/101 A Glossary of Genetics TermsGene:basic unit of inheritance for all living organismsGenome:Genetic endowment of a speciesGene mapping:Determining location of genes on chromosomeGene sequencing:Determining identity of genes from the distinctive order(sequence)of base pairs,such as A-T and G-CChromosome:Threadlike structure in the nuclei of plant and animal cells;it carries the linearly arranged genetic units(genes)2021/9/102 A Glossary of Genetics TermsNucleic acid:Large,chainlike molecule of phosphric acid,sugar and purine and pyrimidine basesMarker:Gene with a known location on a chromosomeTemplate:Macromolecular model for another macromolecule,as in the synthesis of RNA from a DNA templateTransgenic:Organism,such as a mouse,containing experimentally transferred genetic material from another organism,such as mammalMutation:Abrupt change in the genotype of an organism that is not the result of recombination 2021/9/103 A Glossary of Genetics TermsRecombination:Formation in offspring of genetic combinations not present in parentsGenotype:The genetic constitution of an individualPhenotype:The observable characters of an organism;the result of the way the genes are expressedGenetic defect:Pathological changes that occur by duplication,deletion or rearrangement of DNATranscription:The process by which RNA is formed from DNANucleotide:The structural unit of nucleic acid2021/9/104 A Glossary of Genetics TermsRT-PCR:Reverse transcriptase polymerase chain reaction Gene therapy:A technique for correcting defective genes responsible for disease development DNA microarray:An experimental tool for obtaining high-throughput gene expression data Stem cell:have the remarkable potential to develop into many different cell types in the body.Serving as a sort of repair system for the body,they can theoretically divide without limit to replenish other cells as long as the person or animal is still alive.When a stem cell divides,each new cell has the potential to either remain a stem cell or become another type of cell with a more specialized function,such as a muscle cell,a red blood cell,or a brain cell.2021/9/105 Milestones of GeneticsDiscover the double-helix structure of DNA-by James Watson and Francis CrickMapping the human genome-The Human Genome Project,completed in 2001Create the first recombinant DNA molecule-by Paul Berg2021/9/106 Discover the DNA structure1953-James Watson/Francis CrickDouble-helix structure of DNA2021/9/107 Biography-James Watson Born in Chicago,April 6,1928 His fathers ancestors were originally of English descent His mothers father was Scottish-born taylor married to a daughter of Irish immigrants who arrived in the US about 1840Spent entire boyhood in Chicago2021/9/108 Biography-James Watson Study at University of Chicago at 1943In 1947,received a B.Sc.degree in Zoology During these years,his boyhood interest in bird-watching had matured into a serious desire to learn geneticsHis Ph.D thesis was a study of the effect of hard X-rays on bacteriophage multiplicationIn 1950,received Ph.D degree in Zoology at Indiana University 2021/9/109 Biography-James Watson In the spring of 1951,he change his direction of his research toward the structural chemistry of nucleic acids and proteinsMet Crick at 1952,common interest in solving the DNA structureSolved in early March,1953-the proposal of the complementary double-helical configuration2021/9/101019531955 at the California Institute of Technology as Senior Research Fellow in Biology 1956,Assitant Professor,Harvard Biology Department1958,Associate Professor1961,Professor Biography-James Watson 1962,The Nobel Prize in Physiology or Medicine2021/9/1011Born on June 8,1916 at Northampton,EnglandIn 1937,obtained a B.Sc.In Physics at LondonDuring the war,he worked as a scientist for the British Admiralty Biography-Francis CrickLeft the Admiralty in 1947 to study biologyStarted to learn biology in 1937,interrupted by World War Two2021/9/1012Joined the Medical Research Council Unit since 1949Restarted in 1950,obtained Ph.D in 1954 Biography-Francis Crick1962,The Nobel Prize in Physiology or MedicineDied at 2004Worked out the general theory of X-ray diffraction by a helix2021/9/1013Born on June 30,1926,New York Biography-Paul BergBest known for his development of a technique for splicing together DNA from different types of organisms.His achievement gave scientists a tool for studying the structure of viral chromosomes and the biochemical basis of human genetic diseases.Gained early recognition/influence when he delineated the key steps in which DNA produces proteinsAwarded the Nobel Prize for Chemistry in 19802021/9/1014 The Human Genome ProjectBegan at 1990Draft sequence was published in 2001Founded by US department of Energy(DOE),US National Institute of Health(NIH)in collaboration with Britains Wellcome trust2021/9/1015 The Human Genome ProjectCelera Genomics,a private company based in Maryland,is publishing its findings in Science.Human have about 30,000 genes A public international effort,led by the United States,is publishing its analysis of the genome in Nature,a British journal.Genetic differences between any two people are relatively small2021/9/1016 The Human Genome Project-more powerful toolsDurg development,customizing drugs to individual genetic profilesEarlier diagnosis of disease 2021/9/1017 In Vitro Fertilization-historyThe technique was developed in the UK by Dr.Patrick Steptoe and Robert EdwardsFirst “test tube“baby:In UK,Louise Brown(July,1978The first in US:Elizabeth Carr by Dr.Howard and GS Jones(1981)Second “test tube“baby:In India,Kanupriya Agarwal by Dr.Mukhopadhyay(Oct,1978)Since then,IVF has exploded in populatiry,accournts 1%of all birth,115,000 in total in US2021/9/1018 The first“test-tube“baby In Vitro Fertilization-historyLouise Brown born in England in July 25,11:47 PM,197825 y1y With parents 2021/9/1019 In Vitro Fertilization-historyOldham General HospitalDr.Patrick SteptoeDr.Robert EdwardsAt birth2021/9/1020 In Vitro FertilizationThe first phase consists of stimulating the ovary with hormones injected,in order to cause several eggs to matureNormally,only one egg matures per menstrual cycle,so additional hormones are usually required to prevent the body from negatively to this excess of eggsPhase 1:The last injection given is that of human chorionic gonadotropin(hCG),the hormone normally produced during pregnancy2021/9/1021 In Vitro FertilizationThe second phase,that of egg retrieval,occurs about 34-36 hours after the hCG injectionThe entire procedure usually takes8-20 minsPhase 2:2021/9/1022 In Vitro FertilizationThe third phase involves fertilization of the eggsPhase 3:2021/9/1023 ICSI-Intracytoplasmic sperm injection1232021/9/1024 In Vitro FertilizationPhase four is the actual embryo replacementA pregnancy test usually is done 12-14 days after retrievalPhase 4:2 Cell embryo4 Cell embryo8 Cells embryo2021/9/1025 Thumbing through the encyclopedia of lifeTechnology often drives science,science drives medicine,and medicine is always pushing society in to ethical cornersDr.Mark Hughes2021/9/1026 Prenatal Genetic AnalysisOne of the ethically most problematic applications of geneticsIf detected in the fetus,are incurable,may lead to selective abortionPrenatal diagnosis of genetic traits typically can only provide information to assist the prospective parents in their decision making whether to carry the pregnancy to term or to terminate it2021/9/1027 Prenatal Genetic AnalysisIt requires both a medical indication and informed conset of the parentsParents have a right to refuse medically indicated prenatal diagnosis even if there is a high risk for fetal condition that is incompatible with lifeThere are a few genetic traits(such as gender)are accessible to prenatal diagnosis today but unrelated to health2021/9/1028 Prenatal Genetic AnalysisPrenatal diagnosis is carried out only to give parents and physicians information about the health of the fetusThe use of prenatal diagnosis for paternity testing,except in cases of rape or incest,or for gender selection,apart from sex-linked disorders,is not acceptableWHO 19982021/9/1029 Prenatal Genetic AnalysisHeterozygosity testing for recessive disease could only be attempted for eugenic purposesGregor Mendel 18221884Mendels law of independent assortment孟德儿独立分配定律Mendels law of segregation孟德儿分离定律2021/9/1030 Novel parameters for prenatal selection-gene testingCarrier screening,which involves indentifying unaffected individuals who carry one copy of a gene for a disease that requires two copies for the diasese to be expressedPreimplantation genetic diagnosis(screening Embryos for disease)Newbone screening Presymptomatic testing for predicting developing adult-onset disorders such as Huntingtons diseasePresymptomatic testing for estimating the risk of developing adult-onset cancers and Alzheimers diseaseConfirmational diagnosis of a symptomatic individualForensic/identity testing2021/9/1031Gene testing-HDHuntingtons disease(HD):Usually midlife onset;progressive,lethal,degenerative neurological diseaseCaused by a single abnormal geneAn autosomal dominant disorder 2021/9/1032Gene testing-SMAOne of the neuromuscular diseases.Muscles weaken and waste away(atrophy)due to degeneration of motor neurones which are nerve cells in the spinal cord Gene was located Proximal portion of the long arm of chromosome 5,19902021/9/1033Gene testing-Fanconi SyndromeA disorder in which the proximal renal tubules of the kidney do not properly reabsorb electrolytes and nutrients back into the bodyExcessive drinking,urination and glucose in the urineMuscle wasting,acidosis and poor condition will also occur2021/9/1034 Pre-implantation diagnosisSingle cell analysis2021/9/1035Technology:RT-PCR 2021/9/1036Technology-RT-PCRElectrophoresis 2021/9/1037DNA microarray 2021/9/1038Gene therapyA normal gene may be inserted into a nonspecific location within the genome to replace a nonfunctional gene.This approach is most commonAn abnormal gene could be swapped for a normal gene through homologous recombinationThe abnormal gene could be repaired through selective reverse mutation,which returns the gene to its normal functionThe regulation of a particular gene could be altered2021/9/1039Dr.Mark HughesA Professor and Director of Molecular Medicine and Genetics at Wayne State University and Director of the Genomics Center Hub for the State of Michigans Life Sciences Corridor.His work has centered on understanding gene expression in the early human embryo He pioneered the field of PGD for couples at very high reproductive genetic risk and offers this technology in conjunction with IVF Centers in the U.S.and Canada.2021/9/1040Bypassing the natrual method of conceptionDiscarding excess embryosContributes to overpopulationEthical challengesCreating life in the laboratoryFertilizing more embryos than will be neededUnnatural environment for embryos2021/9/1041Potential to select embryosPotential to modify embryosEthical challengesPotential to creat embryos for medical purposes2021/9/1042Alteration of genetic traits:Beauty/handsome,longevity,healthyPotential to modify embryos2021/9/1043A girl or boy,you pick?Potential to select embryos2021/9/1044We can test for lots of things,the question is,should we?-Dr.Mark HughesEthical challenges2021/9/1045