Genetics Dr Pracheth R Outline Advances in genetics

Genetics Dr. Pracheth R.

Outline • Advances in genetics • Prevention of genetic disorders

Advances in molecular genetics • DNA sequencing methods üKnow precise order: nucleotides üIdentify mutations

Advances in molecular genetics • Polymerase Chain Reaction (PCR): üAmplify single copy/few copies : DNA üSimple, rapid diagnosis üMalignant : leukaemia, lymphoma; infections

Advances in molecular genetics • Genetic engineering: üDirect manipulation: organism’s genome using biotechnology üMedicine, research, agriculture

Advances in molecular genetics • Genetic cloning: üProduce similar populations: genetically identical individuals. üCreate copies of DNA fragments, cells or organisms üRecombinant insulin genes. üProduce vaccines as recombinant proteins

Advances in molecular genetics • Gene therapy: üIntroduce gene sequence : cell- modify behaviour üCorrect genetic mutation üKill a cell: cancer üModify susceptibility: cancer

Advances in molecular genetics • Gene therapy: ü Introducing virus / receptor targeting üEthically correct

Advances in molecular genetics • Stem cell therapy: üUse of stem cells : prevent disease üBone marrow transplant üUmbilical cord blood

Human Genome Project • Determine sequence : base pairs- DNA • Identify, map all genes of a human genome • World’s largest collaborative International project • Identify mutations, genotype viruses

Human Genome Project

Human Genome Diversity Project • Define genetic relationships • Interpret: natural selection, genetic drift, migrations

Population genetics • Study: genetic composition, factors determine inherited traits • Hardy-Weinberg experiment • Law: Relative frequencies: each gene alleleconstant, absence of forces.

Factors: influence gene frequencies • Mutation: ü Change in genetic material • Natural selection: üHarmful genes: eliminated, favourable: kept üDDT initially harmful: houseflies

Factors: influence gene frequencies • Population movements: üMigration: change in distribution of genes • Breeding structure: üAll marriages random: genetic equilibrium üSelectively marry: in practice üOpen societies: more freedom -marriage

Preventive and social measures. Health promotion • Eugenics: üImprove genetic endowment: human race üPrevent chromosomal anomalies, genetic defects ØNegative eugenics: üEliminate weak üUndesirable traits: sterilized üLimitation: can’t arrest mutations/control marriage-heterozygotes

Health promotion ØPositive eugenics: üImprove genetic composition üCarriers of desirable genotype: reproduce üMajority : traits not transmitted simple fashion, complicated.

Health promotion • Euthenics: üImprove quality: environment üMentally handicapped improved: environmental stimulation.

Genetic counseling • Offering advice: improve genetic constitution • Prospective: üCouples: genetic risk üBefore they produce their first affected child üUnmarried heterozygote carriers: risk marry heterozygote. üAlready married: termination of pregnancy: unfavourable diagnosis

Genetic counseling • Retrospective: üReport voluntarily: after birth-child üExplain risk: further pregnancies üDiscuss: facilities prenatal diagnosis

Other health promotion measures • Prevent consanguineous marriages (albinism, phenylketonuria) • Avoid late marriages in women

Specific protection • Avoid exposure : X-rays, ionizing radiations • Immunize: rubella before pregnancy (teenage) • Immunize Rh-ve mothers: Anti D globulin.

Early diagnosis and treatment • Prenatal screening procedures: üUltrasound: fetal malformations, growth abnormalities üAmniocentesis: ØTrans-abdominal aspiration: amniotic fluiduterus: 12 -14 weeks ØBiochemical tests: alpha fetoprotien: NTD, spina bifida ØCulture of fetal cells: IEM

Continued…. üChorionic Villus Sampling ØDetect biochemical, structural anomalies.

Early diagnosis and treatment • Neonatal screening procedures: üClinical examination: CDH, hypothyroidism üBiochemical: phenylketonuria, G 6 PD üHb electrophoresis: sickle cell anaemia üOnce diagnosed: treated completely/partially

Early diagnosis and treatment • General population screening measures: üIdentify: at risk- genetic disorders üObjective: diagnose before symptoms üModern technology: DNA analysis Population based genetics: great future

Summary

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