Genetic Testing and Assessment (PDF)

BSMT 2| PCMT 7: CYTOGEN LESSON 4 (MIDTERM): GENETIC TESTING AND ASSESSMENT AMNIOTIC FLUID GENERAL GUIDELINES -Amniotic fluid surrounds the embryo and fetus during deve...

BSMT 2| PCMT 7: CYTOGEN LESSON 4 (MIDTERM): GENETIC TESTING AND ASSESSMENT AMNIOTIC FLUID GENERAL GUIDELINES -Amniotic fluid surrounds the embryo and fetus during development MAIN TOPIC SUB TOPIC UNDERSUB TOPIC GENETIC DISEASE Genetic disease or genetic predisposition to disease -present in gametes before conception; FUNCTIONS -therefore, theoretically, it can be -It protects the fetus in the event the detected from that point on. maternal abdomen is the subject of -If the capability exists for identifying a trauma specific mutation, one can do so in -protects the umbilical cord by providing gametes, in the zygote immediately after a cushion between the fetus and the conception, in the early embryo, umbilical cord, thus reducing the risk of prenatally throughout pregnancy, in the compression between the fetus and the newborn period, in childhood or uterine wall. adolescence as part of reproductive planning in adulthood or thereafter. -it serves as a reservoir of the fluid and nutrients for the fetus containing: GENETIC ASSESSMENT proteins, electrolytes, immunoglobulins, TECHNOLOGIES FOR GENETIC and vitamins from the mother. TESTING -Chromosomal During the embryonic period, amniotic -Biochemical fluid derives from both fetal and -DNA- based techniques maternal factors such as water from the maternal serum, coelomic fluid, and fluid BIOLOGICAL TEST SAMPLES from the amniotic fluid from the amniotic -Blood cavity; however, during late gestation, -Amniotic fluid amniotic fluid is largely produced by fetal -Tissue urine and lung secretions. Amniotic fluid is less viscous and always Sample Creatinine Urea clear due to its lower protein mg/dL mg/dL concentration. Amniotic fluid is 98% Amniotic 300 lipids and hormones make up the other urine 2% HYDRAMNIOS AMNIOCENTESIS -If there is a failure in swallowing -The needle from the amniotic sac amniotic fluid, it will accumulate the aspirates amniotic fluid amniotic fluid around the fetus called -This is a transabdominal procedure. Hydramnios. -Transvaginal amniocentesis. This -This will lead to fetal distress which is method carries a great risk of infection. usually seen in the neutral tube defect. -This procedure is safe if performed -It will occur in 1% of the pregnancy after the 14th week of gestation. -This may occur in diabetic mothers -Fluid for chromosomal analysis is collected after the 16th week of gestation. OLIGOHYDRAMNIOS -It is decreased amniotic fluid seen in -In case of fetal distress and maturity increased swallowing of fluid, urinary are collected in the 3rd trimester tract abnormalities, and membrane leakage, -30 mL of amniotic fluid is collected in -This may occur due to the abnormality the sterile syringes. of maternal, fetal, or placenta -The first 2 to 3 mL collected is complications. discarded because this may be contaminated by the maternal blood, After 20 weeks, the amniotic fluid tissue, and cells volume varies from 500 mL to 1000 mL. -In this case of hemolytic disease of the a. Creatinine, urea, and uric acid newborn, the sample should be avoided concentration increase while from light, The sample should kept in an glucose and protein amber-colored bottle or test tube. concentrations decrease -The sample for fetal lung maturity b. The concentration of urea and should be placed in ice for delivery to creatinine is much lower in the the laboratory and kept in the fridge. amniotic fluid in the maternal urine -The sample for the cytogenetics may possessing then (e.g., cancer) be maintained at room temperature (37 C) before analysis. MUTATIONS -The sample for the biochemical testing -can occur as a result of should be separated immediately from the cellular elements and debris to avoid Mistake in coding in the the effect of cellular metabolism. coding nucleotides Rearrangements within the GENETIC ANALYSIS gene, insertion of new GENOTYPE AND PHENOTYPE genetic material into the -Study of an individual’s phenotype or gene, observable properties can provide Duplication or deletion of information about modes of inheritance, parts or all of a gene allowing estimates for risk of recurrence. MOLECULAR BASIS FOR MONOGENIC INHERITANCE - Disorder resulting from changes in one gene alone (e.g., cystic fibrosis, sickle -Done by examining the specific cell anemia, Duchenne muscular structure and function of genetic dystrophy) material, or DNA. Locating a disease- causing gene on a chromosome and MULTIFACTORAL isolating it. -Disorder resulting from changes in several genes, usually in combination GENE EXPRESSION with an environmental influence -How the organism carries out the (ex: coronary heart disease) instructions of the DNA to create products that are essential for structure -Multifactorial disorders (e.g., common and function of all cells in the body. types of coronary heart disease and Heredity variation is the result of most forms of diabetes) tend to affect far changes- or mutations – in DNA. more individuals than do monogenic disorders. GERM CELLS AND SOMATIC CELLS GENETIC TESTING -Encompasses the use of specific -Changes that occur in germ cells (cell assays to determine the genetic status or sperm) are inherited by offspring. of individual already suspected to be at Changes that occur in somatic cells increased risk for a particular inherited (body cells other than egg or sperm) are condition because of family history or not passed to future generations but can clinical symptoms. result in disease for the individual  DISCOVER DETECTED ON GENETIC SCREENING NEWBORN SCREENING (US) -defined as the use of various genetic tests to evaluate populations or groups -Phenylketonuria of individuals independent of a family -Hypothyroidism history of a disorder or symptoms. -Galactosuria -Maple Syrup Urine Disease -Homocystinuria GENETIC COUNSELING -Cystic Fibrosis-Carrier Disease Refers to the communication process by -Sickle Cell Disease-Carrier disease which information about the nature, -Tay- sachs Disease- carrier disease recurrence risk, burden and reproductive options of a genetic information, as well as empathic counseling and support NEWBORN SCREENING PHI FAST concerning the implication of such FACTS genetic formation, is provided to individuals and their family members. -Newborns should be screened shortly Dent of a family history of a disorder or after 24 hrs of birth. symptoms. -RA9288 or new born screening act was signed in 2004 NEWBORN SCREENING -The Philippine NBS program screens more than 92 congenital disorders -Screening tests are designed to speedily and inexpensively evaluate a -Most babies with congenital metabolic large number of test samples. disorders look normal at birth -these blood samples are collected on -With proper treatment & management, filter paper spots obtained from “heel- babies with genetic disorders grow up sticks” of newborn infants. healthy and lead normal lives -Expanded Newborn screening is included in Phil Health’s new care Package 6 DISCOVER DETECTED ON NEWBORN SCREENING (PHI) -Congenital Hypothyroidism (CH) -Congenital Adrenal Hyperplasia (CAH) -Phenylketonuria (PKU) -Galactosemia (GAL) -Glucose-6- Phoshate Dehydrogenase (G6PD) Deficiency -Maple Syrup Urine Disease (MSUD) EXPANDED NEWBORN SCREENING - Glucose-6- Phoshate Dehydrogenase (G6PD) Deficiency| -Congenital Hypothyroidism (CH) -Congenital Adrenal Hyperplasia (CAH) -Galactosemia (GAL) -Phenylketonuria (PKU) -Maple Syrup Urine Disease -Cystic Fibrosis -Biotinidase Deficiency -Organic Acid Disorders -Fatty Acid Oxidation Disorders -Amino Acid Disorders -Urea Cycle Disorders -Hemoglobin Disorders