1. Genetic screening

2. Uses  Carrier screening  Screening pre-implantation embryos  Prenatal diagnostic screening  Newborn screening  Pre-symptomatic screening in adults  Confirming diagnosis © 2010 Paul Billiet ODWSODWS

3. Tests  Over 1000 tests available Alzheimer's disease* (APOE; late-onset variety of senile dementia) Inherited breast and ovarian cancer* (BRCA 1 and 2; early-onset tumors of breasts and ovaries) Hereditary nonpolyposis colon cancer* (CA; early-onset tumors of colon and sometimes other organs) Cystic fibrosis (CF; disease of lung and pancreas resulting in thick mucous accumulations and chronic infections) Hemophilia A and B (HEMA and HEMB; bleeding disorders) Huntington's disease (HD; usually midlife onset; progressive, lethal, degenerative neurological disease) Phenylketonuria (PKU; progressive mental retardation due to missing enzyme; correctable by diet) Sickle cell disease (SS; blood cell disorder; chronic pain and infections) © 2010 Paul Billiet ODWSODWS

4. Gene probes  Short pieces of DNA or RNA (100 – 1000 bases) complementary to a given sequence of nucleotides  Target DNA denatured (strands separate)  Probe added and binds to complementary sequence  Radioactive marker attached to probe so it can be identified © 2010 Paul Billiet ODWSODWS

5. FISHing for genes  FISH = Fluorescent In Situ Hybridisation  Used to identify chromosomal abnormalities and mapping chromosomes Image Credit: Journal of Medical Gdenetics FISH analysis of a chromosome abnormality where material is switched between chromosomes 9 and 11FISH analysis of a chromosome abnormality where material is switched between chromosomes 9 and 11

6. Pros  Identifying potential parents of affected children  Identifying pre-symptomatic adults © 2010 Paul Billiet ODWSODWS

7. Cons  Lab errors (false positives/false negatives)  Uncertainties in diagnosis from positive result  Lack of medical treatment in case of positive test  Risk of discrimination © 2010 Paul Billiet ODWSODWS