1.HEALTH PROMOTIONAL MEASURES: A.EUGENICS: a.Negative eugenics: AIM:To reduce the frequency of hereditary disease and disability in the community to as low as possible
B.POSITIVE EUGENICS: AIM:To improve the genetic composition of the population by encouraging carriers of desirable genotypes.
B.EUTHENICS : Studies with mentally retarded childrenindicated that exposure to environmentalstimulation improved their IQ.This environmental manipulation is calledeuthenics.
They are of 2 types: 1.Prospective 2.Retrospective1. Prospective genetic counselling:This allows for the true prevention of disease.
This approach requiresIdentifying heterozygous individuals for any particular defect by screeningExplaining to them the risk of their having affected children if they marry another heterozygote for the same gene.
If heterozygous marriage can be prevented or reduced,the prospects of giving birth to affected children will diminish.EX: Sickle cell anaemia Thalassemia2. Retrospective genetic counselling: Most genetic counselling at present is retrospective,i.e,the hereditary disorder has already occurred within the family .
A survey carried out by the WHO showed that genetic advice was chiefly sought in connection with congenital abnormalities Mental retardation Psychiatric illnes Inborn errors of metabolism Premarital advice
The WHO recommends the establishment of genetic counselling centres in sufficient numbers in regions where infectious disease and nutritional disorders have been brought under control And in areas where genetic disorders have always constituted a serious public health problem.
The methods which could be suggested under retrospective genetic counselling are:1. Contraception2. Pregnancy termination.3. Sterilization
OTHER GENETIC PREVENTIVE MEASURES1.CONSANGUINEOUS MARRIAGES: When blood relatives marry each other there is an increased risk in the offspring of traits controlled by recessive genes and those determined by polygenes.EX: Albinism, Alkaptonuria, Phenylketonuria
An increased risk of premature death is alsonoted in such offspring.Therefore , a lowering of consanguineousmarriages would be advantageous to thehealth of the community.
2.LATE MARRIAGES: Trisomy or mongolism is more frequent in children born of elderly mothers. Hence early marriage of females is better than late marriage from the point of view of preventing mongolism.
SPECIFIC PROTECTION: Patients undergoing x-ray examination should be protected against unnecessary exposure of the gonads to radiation. X-ray examination of the pregnant uterus to determine the twins or the lie of the foetus is to be strongly deprecated.
Rh haemolytic disease of the newborn whichis a genetically determined immunologicaldisorder is now preventable by immunizationby anti D globulin.
EARLY DIAGNOSIS AND TREATMENT:1.DETECTION OF GENETIC CARRIERS : It is possible to identify the healthy carriers of a number of genetic disorders, especially the inborn errors of metabolism.
2.PRENATAL DIAGNOSIS:INDICATIONS:- Advanced maternal age- Previous child with chromosome aberration- Intrauterine growth delay- Biochemical disorders- Congenital anomaly- Screening for neural tube defects and trisomy.
3.SCREENING OF NEWBORN INFANTS:Screening tests for early diagnosis of :- chromosome abnormalities- congenital dislocation of hip- congenital hypothyroidism- sickle cell disease- cystic fibrosis
Genetic counselling can have the greatest impact when individuals or couples at genetic risk are identified, before they have developed symptoms themselves or produced their first affected child.
REFERENCETEXT BOOK OF PREVENTIVE ANDSOCIAL MEDICINE : PARK