genetic tests.pptx

genetic tests

1. SEMINAR ON GENETIC TESTING PRESENTED BY: M.C.KNIRANDA 1 ST YEAR M.Sc.(N) SNSR, SHARDA UNIVERSITY.

2. Genetic testing is "the analysis of chromosomes (DNA), proteins, and certain metabolites in order to detect heritable disease-related genotypes, mutations, phenotypes, or karyotypes for clinical purposes.” It can provide information about a person's genes and chromosomes throughout life. OR Genetic testing is a broader sense includes tests for the possible presence of genetic disease, or mutant form of genes associated with increased risk of developing genetic disorders. OR

3. CONTD….. Genetic tests are tests on blood and other tissue to find genetic disorders.

4. BASIS OF GENETIC DIAGNOSIS

5. PRESYMPTOMATIC AND PREDISPOSITION TESTING

6. PRESYMPTOMATIC TESTING:- It helps to identify a person who will develop a genetic disorder such as hemochromatosis. It can help to take preventive measures and making decisions about medical care.

7. PREDISPOSITION TESTING:- Genetic Predisposition - the tendency to develop a health condition as a consequence of the interaction between genetics and lifestyle factors .   This test is the key to taking control of the future of the mother’s well being because her health could lie in her genes. With easy DNA’s genetic health testing service , a mother can understand her health on a genetic level.

8. PRENATAL DIAGNOSIS AND SCREENING

9. Definition: Prenatal diagnosis is any of various diagnostic techniques to determine whether a developing fetus is affected with a genetic disorder or other abnormality. Diagnosis before birth.

10. Indications: Prenatal diagnosis is recommended in the following cases- Parents have had a previous child with a chromosomal abnormality . The pregnant woman is 35 years or older at the time of delivery Mother has a history of recurrent abortions Parental consanguinity

11. CONTD….. The couple is known to be carriers of a chromosomal translocation. The pregnant woman is affected with type 1 diabetes mellitus, epilepsy The pregnant woman is exposed to viral infections The pregnant woman is exposed to excessive medication or to environmental hazards In parents family, a history of down syndrome or some other chromosomal abnormality is present

12. COMMON TECHNIQUES OF PRENATAL DIAGNOSIS

13. THEY ARE AS FOLLOWS:- 1) Ultrasonography 2) Amniocentesis 3) Chorionic villus sampling (CVS) 4) Maternal blood sampling for fetal blood cells 5) Maternal serum alpha-fetoprotein (MSAFP) 6) Maternal serum beta HCG 7) Maternal serum estriol 8) Inhibin-A 9) Pregnancy associated plasma protein-A (PAPP-A) 10) “Triple” or “Quadruple” serum

14. 1) ULTRASONOGRAPHY:- This is a noninvasive procedure that is harmless to both the fetus and the mother . Major internal organs and extremities can best be visualized between 16 and 20 weeks gestation . Ultrasound examination can be quite useful to determine the size and position of the fetus, the size and position of the placenta, amount of amniotic fluid and appearance of fetal anatomy.

15. AMNIOCENTESIS:-

16. 2) AMNIOCENTESIS:- This is an invasive procedure in which a needle is passed through the mother’s lower abdomen into the amniotic cavity inside the uterus . Amniocentesis can be done at about 14 weeks of gestation . For prenatal diagnosis, most amniocentesis are perform between 14 and 20 weeks of gestation.

17. CONTD….. Amniocentesis is useful to determine : Gestational age Position of fetus and placenta Quantity of amniotic fluid Chromosome analysis Fetal lung maturity (3 rd trimester ) Fluorescence polarization

18. 3) CHORIONIC VILLUS SAMPLING:- In this procedure, a catheter is passed via vagina through the cervix and into the uterus to the developing placenta under ultrasound guidance. Introduction of the catheter allows sampling of cells from the placental chorionic villi. These cells can be analyzed by a variety of techniques and also be grown in culture. CVS can be done between 9.5 and 12.5 weeks gestation.

19. CHORIONIC VILLI SAMPLING

20. 4) MATERNAL BLOOD SAMPLING FOR FETAL BLOOD CELLS:- This is a new technique that makes use of the phenomenon of fetal blood cells gaining access to maternal circulation through the placental villi . The fetal cells can be sorted out and analyzed by a variety of techniques to look for particular DNA sequences. Flourescence in-situ hybridization (FISH) is one technique that can be applied to identify particular chromosomes of the fetal cells recovered from maternal blood and diagnose aneuploid condition such as trisomies and monosomy.

21. 5) MATERNAL SERUM ALPHA-FETOPROTEIN TEST:- The developing fetus has two major blood proteins albumin and alpha fetoprotein . MSAFP is a careening test that examines the level of alpha-fetoprotein in the mother’s blood during pregnancy. Blood is drawn from veins in the mother’s arm and sent off to a laboratory for analysis. MSAFP may be performed between the 14 th and 22 nd weeks of pregnancy

22. CONTD….. MSAFP test can be done to determine- Levels of alpha fetoprotein of fetus. Neural tube defect Gestationl age Abdominal wall defect

23. 6) MATERNAL SERUM BETA HCG:- The test is most commonly used as a test for pregnancy. About a week following conception and implantation of the developing embryo in to the uterus, the trophoblast will produce enough beta HCG to diagnose pregnancy . In the later pregnancy beta HCG can be used to determine - Chromosomal abnormalities Down syndrome Molar pregnancy, hydatiform mole

24. 7) MATERNAL SERUM ESTRIOL:- The amount of estriol in maternal serum is dependant upon a viable fetus, placenta and maternal well being . Maternal serum estriol can be useful in determination of General well-being of fetus Down syndrome  

25. 8) INHIBIN-A:- Inhibin is secreted by the placenta and corpus luteum. Inhibin-A can be measured in maternal serum . An increased level of inhibin-A is associated with an increased risk for trisomy 21 . A high inhibin-A may be associated with a risk for preterm delivery.

26. 9) PREGNANCY ASSOCIATED PLASMA PROTEIN-A (PAPP-A):- Pregnancy-associated plasma protein A (PAPP-A) is an important pregnancy protein . Low level of PAPP-A as measured in maternal serum during the first trimester may be associated and fetal chromosomal anomalies including trisomies , 13, 18, 21 . Low PAPP-A levels in the first trimester may predict and adverse pregnancy outcome including a small for gestational age or still birth.

27. 10) “TRIPLE” OR “QUADRUPLE” SCREEN:- The triple screening measures the amounts of three substances in a pregnant woman's blood: alpha-fetoprotein (AFP), human chorionic gonadotropin ( hCG ), and estriol (uE3). When a test for the hormone inhibin A is added, it's called a quad screening.