Transcript Powerpoint Presentation: Genetic Screening

Genetic screening
Uses
Carrier screening
 Screening pre-implantation embryos
 Prenatal diagnostic screening
 Newborn screening
 Pre-symptomatic screening in adults
 Confirming diagnosis

© 2010 Paul Billiet ODWS
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 ODWS
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
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© 2010 Paul Billiet ODWS
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 11
Pros
Identifying potential parents of affected
children
 Identifying pre-symptomatic adults

© 2010 Paul Billiet ODWS
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 ODWS