GENETIC TESTING : The analysis of chromosomes, DNA, proteins To detect abnormalities that may cause a genetic disease EXAMPLES OF GENETIC TESTING : 1.PRENATAL DIAGNOSIS 2.HETEROZYGOTE CARRIER DETECTION 3.PRESYMPTOMATIC DIAGNOSIS OF GENETIC DISEASE

SCREENING TESTS Aimed at identifying a subset of the population on whom further. DIAGNOSTIC TEST Are not intended to provide definitive diagnoses. Designed to detect treatable human diseases in their presymptomatic stage.

EXAMPLES OF SCREENING TEST: PAP TESTS - Recognition of cervical dysplasia. POPULATION SCREENING -the presumptive identification of an unrecognized defect by the applction of test/examinations/othr prcedure -to sort out apparently well persons who probably hv a dz frm those who prbbaly do not. -for hypercholesterolemia.

PRINCIPLES OF SCREENING DISEASE CHARACTERISTICS Serious & relatively common Natural history – clearly understood Acceptable & effectve treatmt. Prenat diagnosis shld availble. TEST CHARACTERISTICS Acceptable to the population Easy to perform Relatively inexpensive Valid & reliable SYSTEM CHARACTERISTICS Resources fr diagnosis & treatmnt of disorder must be accessible.

GENETIC SCREENING

What is genetic screening? One of the fastest moving fields in medical science. A technique to determine the genotype or phenotype of an organism. It is often used to detect faulty or abnormal genes in an organism.

TYPES OF GENETIC SCREENING: 1.Newborn Screening -for inherited metabolic diseases 2. Heterozygote Screening -for Tay-Sachs disease

Newborn Screening Newborns are tested for diseases and early diagnoses allows for immediate treatment (early detection &effective intervention). A blood sample is tested for genetic disorders. An effective public health strategy for treatable disorder such as PKU, galactosemia, hypothyroidism & sickle cell disease. Some communities begun screening for Duschenne muscular dystrophy (by measuring creatine kinase levels in newborns)

Heterozygote Screening To detect unaffected carriers of disease- causing mutations Target population: group known to be at risk. Usually genetic diseases involves in this heterozygote screening is “autosomal recessive disorder”- Tay-Sachs disease,  - Thalassemia & Cystic fibrosis.

Presymptomatic Diagnosis Indivisuals who are known to be at risk for a disorder can be tested (generally bcz of a (+)ve family history. To determine whether they have inherited a disease-causing mutation before they develop clinical symptoms of the disorder. Ex: Huntington Disease, adult polycystic kidney disease, hemochromatosis & autosomal dominant breast cancer.

Advantage of Presymptomatic Diagnosis Can aid in making reproductive decisions. Can provide reassurance to those who learn that they do not carry a disease-causing mutation. Early diagnosis may improve health supervision.