Grody Flashcards
Amniocentesis
Invasive 15th week (later than CVS)
Chorionic Villus Sampling (CVS)
Invasive
10-12th week
Does NOT detect neural tube defects
Fetal blood sampling (PUBS)
Invasive
used for sickle cell before but not just take sample of amniotic fluid
Fetal tissue biopsy
Invasive
used for muscular dystrophy before but used to see mutations in amniocytes
Which two sampling methods are not used anymore?
PUBS and fetal tissue biopsy
Pre-implantation genetic diagnosis
Used in IVF
Grow to 8 cell stage, take one cell out and run PCR
If mutation throw it out
Only implant healthy embryos
DMD genetics
Largest gene known
Deletions found in 2/3 of pts
Multiplex PCR
Detects deletions
Used to test for DMD
Cystic Fibrosis
Sx: abnormal secretions, chronic pulmonary disease
Screening: microarray of 16 mutations
Genetics: deltaF508 (deletion of phenylalanine at codon 508); autosomal recessive
What do BRCA1 and 2 do normally?
help repair damaged DNA or destroy cells if DNA cannot be repaired
How do BRCA1 and 2 increase risk for breast and ovarian cancer?
20% by age 40
50% by age 50
87% by age 70
BRCA genetics and screening
Genetics: autosomal dominant
Screening: DNA screening gold standard
Possible results of BRCA DNA screening?
Positive: proceed w/tx
No mutation: mutation previously identified or no known mutation
Identified mutation has uncertain clinical sig: further testing needed
Why are southern blots used for tri-nucleotide repeat disorders?
Because the product is too big to show up on PCR
Full mutation for Fragile X
200-1000 repeats