Genetic screening is the application of a test on people for the systematic early detection or exclusion of a hereditary disease, a genetic predisposition to a disease, or to determine whether a person carries a predisposition which may produce a hereditary disease in their offspring.

Genetic screening may be used in populations at risk for a particular genetic disorder. A sufficient benefit must be derived from a screening program to justify its cost. High-quality evidence that a reasonable proportion of participants would see the benefits as outweighing the harms is also important in the decision to offer genetic screening. Genetic screening is only appropriate when

• the natural history of the disease is understood;
• the screening tests are valid and reliable;
• sensitivity, specificity, false-negative, and false-positive rates are acceptable; and
• effective therapy is available.

1. Heterozygote screening: Screening a susceptible population [eg, Tay-Sachs disease in Ashkenazic Jews, sickle cell anemia in blacks, thalassemia in various ethnic groups) may be appropriate because of the high frequency of heterozygote. Screening can determine if a person is a carrier for a specific gene and disorder.If the partner is also heterozygote, the couple are at risk of having affected offspring.
2. Presymptomatic genetic screening: Presymptomatic genetic screening may be appropriate for persons with a family history of a dominantly inherited disorder (eg, Huntington’s disease, “breast cancer).                                                           –
3. Prenatal diagnosis:-Amniocentesis (refer above), chorionic villus sampling, umbilical cord blood sampling, maternal blood sampling, maternal serum screening, and fetal visualization with ultrasound and radiography are useful in prenatal diagnosis.
4. Newborn screening: Screening for phenylketonuria, galactosemia, and hypothyroidism in the newborn allows prophylaxis (i.e., special diet or replacement therapy) to be initiated early enough to prevent severe complications.

Uses-

1. Screening allows couple to make informed reproductive choices.
2. Identifying a definite carrier of the genetic disorder may allow the patient to make informed decisions like monitoring in the case of breast cancer and reproductive choices in the case of Huntington’s disease or adult polycystic kidney disease.
3. To initiate possible treatment to prevent severe complications.
4. Genetic screening helps in explanation to the patients or their parents the genetic or medical implications of the disease.
5. Genetic counseling and antenatal diagnosis provide definite-relief to the possible parents and reduce the frequency of geneticallv defective^– individuals in the population.
6. Defective genes may be corrected through sophisticated genetic techniques.

Participants and professional practitioners should therefore receive balanced information about the different aspects of the genetic screening program.