Human genetics & health
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Human Genetics & Health
Dr Mohan Lal
Associate Professor
Department of Community Medicine
Govt. Medical College, Amritsar
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Over the last Few decades, a significant transition has taken place in the etiology of diseases affecting mankind
Environmentally related disorders have decreased &genetic disorders & non-communicable disorders have become a major cause of morbidity and mortality
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Health of an individual is based on Uncontrollable Factors (genetics, gender,
predisposition to a disease) Controllable Factors (diet, smoking status,
exercise levels)
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Genetics
Study of inheritance dealing with the transmission of hereditary characters from one generation to another.
Human genetics is concerned with the inheritance of human traits & their relationship to the human health
Deals with the herediatry disorders & provide key to their prevention &control .
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Prevalence of Genetic Disorders Prevalence of genetic disorders (excluding
multifactoral genetic disease)-7/1000 live births.
Out of 7, -4 sex linked disorders -2 Autosomal disorders - other characterized by balanced or
unbalanced chromosomal rearrangements Genetic Liability in the community .
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Genetic Disorders
Autosomal Dominant Autosomal Recessive Sex Linked disorders
Retinoblastoma Albinism Hemophilia
Marfan Syndrome Total color blindness Agammaglobunemia
Neurofibromatosis Phenylketouria Red green color blindness
Fibrocystic disease of Pancreas
Neonatal Jaundice
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Diseases Associated with Genetic Predisposition Cancer
Coronary heart disease
Diabetes (Insulin dependent)
Alzheimer’s disease
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Biological Determinant Genetics Predisposition to disease
A person may be at increased risk of inheriting a disease or condition if they have a biological parent who has had the disease.”
Genetics can have an influence on a persons risk to certain conditions or diseases.
Ex: If your parent has high cholesterol, you are at a higher risk of developing high cholesterol.
Examples of diseases – genetic predisposition Alzheimer's disease (before the age of 65)
Migraine headaches Type 1 & 2 diabetes CVD - High blood pressure, hypertension Certain cancers – (including breast and prostate)
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Prevention & Control of Genetic Disorders
1. Prevention
2. Screening
3. Counseling
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Prevention
Primary Prevention
(Prevent birth of an affected newborn)
Secondary Prevention
To Prevent clinical manifestations
in affected individuals by appropriate intervention
Tertiary Prevention
Provision of adequate care &rehabilitation in
affected individuals
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Specific Protection
From X-Ray Early diagnosis by :-
-Detection of carriers
- Prenatal diagnostics
- Amniocentesis
-New born screening
- Pre clinical case recognition
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Screening
Applied at Prenatal, Neonatal& general population levels.
Prenatal & neonatal screening –ideal approach for early diagnosis & prompt treatment of herediatry disorders
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Prenatal Screening
Prenatal screening by:-
-Ultrasonography fetal malformation & fetal growth abnormalities
-Amniocentesis(14-16 weeks of pregnancy ) diagnosis of spina bifida & other neural tube abnormalities.
Chorionic villus sampling technique (10-12 weeks of pregnancy) – Both biochemical & structural abnormalities can be detected.
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Neonatal Screening
Help in detecting herediatry disorders like
-Phenylketouria
-Sickle cell Anemia
-Duchene muscular dystrophy
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Population Screening
To identify individuals at risk of developing herediatry disorders.
Objective:-
- To make presymptomatic diagnosis for arresting the progress of such disease by timely preventive intervention.
-Only such disorders should be Identified for which measures for prevention & treatment are available.
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Genetic Counseling
Genetic counseling -an integral part of the management of patients and families with genetic disorders .
-Retrospective Counseling :- Parents who have already given birth to a child affected with genetic condition
-Prospective Counseling:-with those at high risk for genetic disorders & screens them to find out if they really are affected.
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Genetic Counseling
A educational process by which patients or/& at risk individuals are given information to
understand the nature of the genetic disease, its transmission and the options open to them in
management and family planning
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Essential Components of Counseling History of family background construction
Clinical diagnosis
Confirmatory diagnosis
Calculation of reoccurrence of risk
Counseling
Follow up
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Genetic counseling Process
Beneficiaries :- Individual or coupleWhy?•Have affected child•Are carriers•Have genetic disease in family•Have recurrent abortions•High maternal/paternal age•Exposed to a mutagen/teratogenic•Are consanguineous
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Reaching accurate diagnosis Family history
Physical/clinical examination
Cytogenetic studies/radiology
Laboratory/DNA analysis
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Estimation of Recurrence Risk :-
Family pedigree Applying various
methods Risk calculation -Bayesian -Mendels
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Genetic Counseling :- Available options Risk calculations New developments Disease course Treatment availability
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Decision Making:- Knowledge of disease
recurrence Available options ·Family pressure ·Religious beliefs ·Social status ·Economic status ·Community influence
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Gene Therapy
Means introduction of gene sequence in to cell with the aim of modifying the cell behavior in a clinically relevant fashion.
Used in many ways :- - To correct genetic mutation (as for cystic fibrosis) To kill a cell (as for cancer) To modify susceptibility (as coronary heart disease )
The gene may be introduced using a virus or by means of a lipid or receptor targeting .
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Eugenics
Idea of herediatry improvement by selective breeding propagated by Galton.
Can be defined as improvement of human species or race by selective breeding .
Positive Eugenics:- Applied to animals for increasing milk & have better
quality animals. Improving yield of grains Genetic manipulation for human welfare & survival Negative Eugenics example “purify” German race by
eliminating genetically poor individuals.
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Euthenics
Means providing appropriate / suitable environments for genotype to express themselves fully.
Euthenics measures must be comprehensive to include physical,intellectual,social & cultural components whereby genetically disadvantaged individuals can achieve a reasonable degree of development
Measures to improve the environment in order to improve health, appearance, behavior, or well-being of society.
Lead an independent existence.
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Genetic Services Medical termination of Pregnancy 1971 lays down
legislative framework of application of genetics science PC-PNDT act 1974- Sex Selective abortions need to be eliminated by
implementation of PC-PNDT Act. Antenatal clinics provide opportunity to educate
individual & family on genetics. Screening of Antenatal mothers for Rh grouping Avoidance of teratogenic drugs & radiation Promoting immunization against rubella before
pregnancy is preventive genetics.
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Contraception for limiting the size of family & bearing children at right age is a example of positive & preventive genetics.
Improving nutritional status & consuption of Iron & folic acid
Use of ultrasonography to detect defective children is essentially a good screening activity.
Early childhood development services in ICDS programme by providing environmental stimuli is an attempt to realize full potential of genetic endowment of young children.
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Thank You