Genetics
Dr. Pracheth R.
Outline
• Advances in genetics
• Prevention of genetic disorders
Advances in molecular genetics
• DNA sequencing methods
Know precise order: nucleotides
Identify mutations
Advances in molecular genetics
• Polymerase Chain Reaction (PCR):
Amplify single copy/few copies : DNA
Simple, rapid diagnosis
Malignant : leukaemia, lymphoma; infections
Advances in molecular genetics
• Genetic engineering:
Direct manipulation: organism’s genome using
biotechnology
Medicine, research, agriculture
Advances in molecular genetics
• Genetic cloning:
Produce similar populations: genetically
identical individuals.
Create copies of DNA fragments, cells or
organisms
Recombinant insulin genes.
Produce vaccines as recombinant proteins
Advances in molecular genetics
• Gene therapy:
Introduce gene sequence : cell- modify
behaviour
Correct genetic mutation
Kill a cell: cancer
Modify susceptibility: cancer
Advances in molecular genetics
• Gene therapy:
 Introducing virus / receptor targeting
Ethically correct
Advances in molecular genetics
• Stem cell therapy:
Use of stem cells : prevent disease
Bone marrow transplant
Umbilical 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:
 Change in genetic material
• Natural selection:
Harmful genes: eliminated, favourable: kept
DDT initially harmful: houseflies
Factors: influence gene frequencies
• Population movements:
Migration: change in distribution of genes
• Breeding structure:
All marriages random: genetic equilibrium
Selectively marry: in practice
Open societies: more freedom -marriage
Preventive and social measuresHealth promotion
• Eugenics:
Improve genetic endowment: human race
Prevent chromosomal anomalies, genetic
defects
Negative eugenics:
Eliminate weak
Undesirable traits: sterilized
Limitation: can’t arrest mutations/control
marriage-heterozygotes
Health promotion
Positive eugenics:
Improve genetic composition
Carriers of desirable genotype: reproduce
Majority : traits not transmitted simple fashion,
complicated.
Health promotion
• Euthenics:
Improve quality: environment
Mentally handicapped improved: environmental
stimulation.
Genetic counseling
• Offering advice: improve genetic constitution
• Prospective:
Couples: genetic risk
Before they produce their first affected child
Unmarried heterozygote carriers: risk marry
heterozygote.
Already married: termination of pregnancy:
unfavourable diagnosis
Genetic counseling
• Retrospective:
Report voluntarily: after birth-child
Explain risk: further pregnancies
Discuss: 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:
Ultrasound: fetal malformations, growth
abnormalities
Amniocentesis:
Trans-abdominal aspiration: amniotic fluiduterus: 12-14 weeks
Biochemical tests: alpha fetoprotien: NTD, spina
bifida
Culture of fetal cells: IEM
Continued….
Chorionic Villus Sampling
Detect biochemical, structural anomalies.
Early diagnosis and treatment
• Neonatal screening procedures:
Clinical examination: CDH, hypothyroidism
Biochemical: phenylketonuria, G6PD
Hb electrophoresis: sickle cell anaemia
Once diagnosed: treated completely/partially
Early diagnosis and treatment
• General population screening measures:
Identify: at risk- genetic disorders
Objective: diagnose before symptoms
Modern technology: DNA analysis
Population based genetics: great future
Summary
THANKS 