|Year : 2020 | Volume
| Issue : 1 | Page : 83-85
Prenatal diagnosis: A connotation on genetic counseling being indispensable
Anuradha Ramesh1, Venkatachalam Deepa Parvathi2
1 Postgraduate Student, Department of Human Genetics, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India
2 Assistant Professor, Department of Human Genetics, Sri Ramachandra Institute of Higher Education and Research, Chennai, Tamil Nadu, India
|Date of Submission||09-Mar-2019|
|Date of Decision||31-Jul-2019|
|Date of Acceptance||14-Feb-2020|
|Date of Web Publication||16-Mar-2020|
Venkatachalam Deepa Parvathi
Department of Human Genetics, Sri Ramachandra Institute of Higher Education and Research, Chennai - 600 116, Tamil Nadu
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Prenatal testing and diagnosis are gaining a strong foothold in a progressively developing country like India, and an estimated boom in the market of noninvasive prenatal testing is predicted by the year 2024. Having said this, every technique needs an adequate amount of supplementation to increase its worth and that is where genetic counseling proves to be indispensable. Postdiagnosis, the women classified as high-risk individuals likely to give birth to infants inflicted with congenital and structural anomalies are appropriately counseled regarding the clinical aspects of the disease, life expectancy associated with the same, and the consequences associated with the decision to go ahead and conceive the child. Genetic counseling is majorly done for Down syndrome as the other aneuploidies have a highly reduced life expectancy. Although there are a variety of techniques available for testing various chromosomal anomalies, information regarding the appropriate time of the test and emphasis on pre- and posttest counseling is usually not supplied to primary physicians. A considerable amount of confusion dominates the decision of which test should be employed for testing of which anomaly as an array of rather efficient techniques has been identified. Furthermore, there is no nation-wide consensus of the timing and nature of these screening protocols. Moreover, ambiguous guidelines along with an impending lacuna in terms of awareness have led to India being at the backseat of the era that has ushered in tons of technological advancement in this field.
Keywords: Chromosomal anomalies, Down syndrome, genetic counseling, prenatal diagnosis, prenatal testing
|How to cite this article:|
Ramesh A, Parvathi VD. Prenatal diagnosis: A connotation on genetic counseling being indispensable. Indian J Public Health 2020;64:83-5
|How to cite this URL:|
Ramesh A, Parvathi VD. Prenatal diagnosis: A connotation on genetic counseling being indispensable. Indian J Public Health [serial online] 2020 [cited 2022 Sep 30];64:83-5. Available from: https://www.ijph.in/text.asp?2020/64/1/83/280761
| Introduction|| |
The Indian subcontinent being overly populous has a higher incidence of genetic disorders which could be attributed to parents being supplied with inadequate information regarding risks posed to the fetus due to consanguinity or other hereditary factors. This could be attributed to insufficient family planning which stems from the lack of education whereby there are more mouths to feed than one can manage. More often than not there is no traceable family history due to which one does not know that there could be chances of a chromosomal anomaly or genetic disease that could affect the child. Invasive procedures such as amniocentesis and chorionic villus sampling dominate the Indian scenario as major protocols employed for prenatal diagnosis, having a market size of over 60%. Due to the higher mortality rates associated with invasive techniques, mothers clamor for tests which do not pose a risk to the life of their unborn child. Although being relatively new, prenatal testing and diagnosis are bound to be a popularly thriving market by the year 2024. In order to prevent the increased incidence of genetic disorders, preventive measures such as counseling and educating potential patients with respect to the risks associated become imperative. Genetic counseling is a branch of science that involves identifying and assessing the likelihood of parents passing on a genetic disease or disorder to their children or further down to future generations. Hence, it serves as a succor to avoid the increased incidence of these diseases.
Review and understanding of this issue are required for at least two purposes to elucidate the current scenario of genetic counseling in India and the existing guidelines for prenatal testing to emphasize the need for increased awareness of genetic counseling postprenatal diagnosis.
| Methods Involved in Prenatal Testing|| |
Ultrasound scanning is an indispensable technique that is used to assess the fetal age and the intrauterine environment. The efficiency of this noninvasive procedure increases manifold when the results are reproducible due to which it is often performed multiple times throughout the course of pregnancy. It consists of two subtypes, namely routine obstetric ultrasound scanning and high-resolution ultrasound scanning wherein the former is performed for normal pregnancies. In populations where the females are categorized as high-risk individuals, the accuracy of ultrasound screening identifying chromosomal and congenital anomalies is well over 90%. Test results usually enhance obstetric management and facilitate increased care to the unborn fetus [Figure 1].
|Figure 1: (a) Techniques involved in prenatal testing; (b) Types of ultrasound.|
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Evaluation of changes in the levels of biochemical markers plays an important role in prenatal screening, wherein it gives an account of whether the woman screened is susceptible to conceiving to a child at risk of exhibiting an anomaly. First-trimester screening involves the screening for markers such as beta-human chorionic gonadotropin (HCG), pregnancy-associated plasma protein A (PAPP-A), nasal bone, and nuchal translucency. Second-trimester screening involves assessing the fluctuations in levels of alpha-fetoprotein (AFP), beta HCG, dimeric inhibin A, and unconjugated estriol. These screening tests are performed for the early detection of trisomy 21, 18, and 13. Decreased levels of PAPP-A and beta AFP and an increase in the level of beta HCG are indicative of Down syndrome (DS) (trisomy 21). A decrease in the levels of all biochemical markers is indicative of Edward syndrome (trisomy 18) and a decrease in levels of PAPP-A and beta HCG followed by an increase in AFP level is suggestive of Patau syndrome (trisomy 13) [Table 1].,,
|Table 1: Fluctuations in levels of biochemical markers indicative of aneuploidies|
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| Necessity of Prenatal Diagnosis and Genetic Counseling|| |
Children suffering from DS have a relatively high life expectancy as compared to those diagnosed with Edwards or Patau which do not survive the process of parturition. Hence, genetic counseling is advised only for those mothers who are in the high-risk category of conceiving a child affected by DS.
DS is a genetic disorder that is attributed to an additional copy of chromosome 21; hence, it is also known as trisomy 21. It is found to occur as a free trisomy 21 or due to a phenomenon known as mosaicism. Free trisomy 21 usually happens when there is nondisjunction of the chromosome during the process of meiosis in gametogenesis. The cells in such an individual exhibit an abnormal karyotype, this accounts for 95% of DS cases. Conversely, in mosaicism there is a mutation in the germline cells due to which a few cells, in the individual originating from the mutated germline show an abnormal karyotype whereas the others have a normal karyotype. This accounts for 3% of DS cases. Robertsonian translocation is another cause of DS and accounts for 2%–4% of the cases in the Indian scenario.
It has an incidence of 1:700–1:1000, which makes it the most common referral for genetic counseling. Since there are no curative measures that can be taken on by individuals to treat down, genetic counseling plays a central role in educating parents on how to deal with children suffering from the same. Being a highly complex and challenging task, it is imperative that knowledge regarding the issue and sensitivity toward the same is put forth appropriately. During these counseling sessions, there are a number of questions posed by the parents' which include whether or not other people might recognize that their child is physically and intellectually compromised, whether the defect was in the mother or the father, if the child would be able to earn his/her livelihood or if ending the child's suffering by possibly killing it is a wise option considering leading this kind of life is worthless. Doubts like life expectancy are not more than 17–18 years or the fact that it is a consequence of insufficient prenatal care stem from the fact that parents are not educated about the condition. This could be due to a variety of reasons which involve difficulty in diagnosing the neonate or the unwillingness of physicians to break the unpleasant news to the parents. More often than not parents are not routinely informed about antenatal care and the various prenatal screening tests available to avoid conceiving a child ridden with chromosomal abnormalities or genetic disorders. Hence, educating the mass and spreading awareness regarding the triple test play an important role.
| Current Scenario of Genetic Counseling in Low- and Middle-Income Countries and India|| |
Genetic counseling aids in the interpretation of test results, thereby helping an individual take an informed decision. The advances in scientific technology have enabled the introduction of genetic testing services in low- and middle-income countries (LMICs) in a cost-effective manner. This is achieved by the international partnerships and research initiatives. Contrastingly, the development of genetic counseling has been unable to follow the set pace and remains a predominantly Western concept and profession. Furthermore, the aggregate of genetic counselors, globally, falls short of the frequency with which their services are required due to which, more often than not, physicians bear the responsibility of genetic counseling. In LMICs, particularly, with the patient load on physicians soaring training in medical genetics is limited. Hence, effective education to support patients is one of the major challenges faced. Genetic counseling in LMICs is usually directive wherein individuals coming from a low socioeconomic background prefer clinicians making decisions for them rather than wanting to learn more about the treatment options. A small proportion of clinicians approach this process with an agenda of eliminating deleterious genes and reducing birth effects in a population thus attempting to improve the quality of life of the affected family. This is touted as a eugenic tendency which is more rampant in LMICs as compared to high-income countries (HICs). It is also suggestive that clinicians native to LMICs are more negative in their elucidation of genetic disease as compared to HICs. Ethical codes for genetic services are either underdeveloped or absent due to which the concepts of protection of patient's rights and informed consent are relatively unheard of. Financial constraints, societal and religious biases, and pressures are major factors that usually deter individuals from LMICs to frequent medical institutions to avail these services.
Although there are a variety of techniques available for testing various chromosomal anomalies, information regarding the appropriate time of the test and emphasis on pre- and posttest counseling is usually not supplied to primary physicians. A considerable amount of confusion dominates the decision of which test should be employed for testing of which anomaly as an array of rather efficient techniques has been identified. Furthermore, there is no nation-wide consensus of the timing and nature of these screening protocols. Moreover, ambiguous guidelines along with an impending lacuna in terms of awareness have led to India being at the backseat of the era that has ushered in tons of technological advancement in this field. Due to this, the optimum benefits of prenatal testing and diagnosis have not been able to traverse its way to the population at large. Genetic counseling with respect to prenatal testing and diagnosis has been prevalent over the decades, but the magnitude of awareness though frugal previously has increased over the past decade. This could be attributed to the increased number of infants being born with various chromosomal anomalies and genetic disorders. The increased incidence of genotypically and phenotypically abnormal progeny in families could have served as a driving force to question why it happens and what could be done to avoid it. This could have led to an arbitrary increase in the number of people visiting medical institutions and hospitals. There has been a surge in the rural population frequenting hospitals regarding the issues of failed pregnancies and genetic counseling regarding prenatal tests and diagnosis. This could be counted as an achievement in itself as increased awareness ticks the main objective of ensuring that the phenomenon rather is preventive than curative. Prenatal testing being a covert field of interest which has shot up in popularity over the last decade has more often than not been confused with being limited to sex determination of the unborn fetus only. This could have been of paramount importance with respect to why it has not been that sought after in the past considering female feticide was and to a certain extent still is rampant in rural India.
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Conflicts of interest
There are no conflicts of interest.
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