PHASE II: COURSE (MED 202) BLOOD AND IMMUNE SYSYEM
Assignment: 17TH SEPT 2015
GENETIC COUNSELLING, ETHICAL ISSUES IN MANAGEMENT OF HEMOGLOBINOPATHIES
Objectives
1. Describe risk assessment in genetic counseling
One of the most important aspects of genetic counseling is the provision of a risk factor. Estimation of the recurrence risk requires consideration of:
i) The diagnosis and its mode of inheritance ii) Analysis of the family pedigree iii) The results of tests, which can include linkage studies using DNA markers.
The probability of an outcome can be defined as the proportion of times it occurs in a large series of events. Since probability is indicated as a proportion of one, a probability of zero …show more content…
The results of carrier tests, which show overlap between carriers and non-carriers can be incorporated in a Bayesian calculation.
Polymorphic DNA markers linked to the disease locus can be used in many single gene disorders for carrier detection, preclinical diagnosis and prenatal diagnosis.
2. Determine the recurrence risk in autosomal recessive disorders such as thalassemia.
With an autosomal recessive condition, the parents of an affected child are both heterozygotes. There are two possible exceptions, both of which are very rare. These arise when only one parent is a heterozygote, in which case the child can be affected if either a new mutation occurs on the gamete inherited from the other parent, or uniparental disomy occurs resulting in the child inheriting two copies of the heterozygous parent’s mutant allele.
When calculating risks in autosomal recessive inheritance, the underlying principle is to establish the probability that both the parents are carriers and then multiply the product of these probabilities by ¼, this being the risk that any child born to two carriers will be affected.
3. Provide a brief outline of the premarital program in the UAE and the tests that are done for …show more content…
Describe the eugenic and dysgenic effects of medical genetics
Eugenics involves the selection of the ‘best’ specimens in a population for breeding to improve that population or remove the undesired traits from the population. Genetic counseling, however, is non-directive and allows for autonomy in reducing the burden of genetic diseases on society should not be confused with the eugenic goal of “improving the gene pool”.
The opposite of eugenics is dysgenics, deterioration in the wellbeing of a population by practices that allow deleterious alleles to accumulate and continue to cause disease. Medical treatment can also be seen in this light as having a dysgenic effect by decreasing the selection against a particular genotype and thereby allowing the frequency of the disease to increase.
A particular concern is the extent to which pregnancy termination for genetic reasons is followed by reproductive compensation – which is by the birth of unaffected children, many of whom are carriers of the gene. An example is that in X-linked recessive disorders, some families choose to terminate pregnancies in which the fetus was male but daughters in this same family are most likely carriers of the disorder. Therefore, in this way, reproductive compensation has the potential of increasing the frequency of the genetic disorder in the long term, which led to the loss of an affected