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Genetics Abnormal Amnio Genetic counseling and Prenatal testing


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Dysmorphology definition
study of abnormal form of birth defects to correctly diagnose a child
common malformation show that first degree relatives are 10-40 fold higher to get it than the general population

sex, family history of malformation and severity can influence this risk
for risk of recurrence of single congenital malformation take:
medical history
family history
phys exam
"risk figs" based on the same pop of proband
Folic acid and pregnancy
help alleviate neural tube defects, classic ex of multifactorial causation
multiple malformation
family/pregnancy history, detailed exam, consulting databases, examining relatives, lab work up (ie chrom analysis)
on genetics webpage doooo iiiiitttttttt
What is the indication for offering amniocentesis or CVS?
high risk groups, less availability, costly, risks, prior/current obstetric history, maternal age, family genetic syndrome, carrier screening, multiple miscarriage
Carrier Screening
(screen mom/dad to see if carrier)
for autosomal and x-linked recessive, and ethnicity screening
Preimplantation genetic Diagnosis (PGD)
test for chromosomal abnormalities in embryo before implantation
Indication -age of mother, infertility treatment, high risk for genetic syndrome,

procedure - blastomere biopsy, single cell removed

risks - testing not available for all genetic mutations, expensive, possibility for error
FIRST study
screen or diagnostic?
detection rates

procedure - biochem markers PAPP-A and free hCG with two ultrasound (nuchal translucency and crown rump length) - better ultrasound

Timing - 9 weeks to 13 weeks 6 days, First trimester

Detection - screen for risk of downs, 18 and 13, rates are dependent on lab,
MAternal serum screen
procedure - what are the biochem markers in a triple screen?


procedure - blood triple screen for AFP hCG and uE3(unconjugated estriol), can also look at inhibin A and ITA(invasive trophoblast antigen)

timing 14-21 weeks

results - trisomy 21 18 and NTDs, levels expressed as MoM(multiples of the mean) and should be 1, screen positive or negative

rates - not as good as FIRST
Level II ultrasounds
Screening - see cleft lip, heart defect, maybe a chrom abnormality, offer invasive testing
single transducer generated image

timing - 18-24 weeks
soft markers for chromosomal abnormalities

detects 95% of ONTD's
screening or diag?


uses and results

timing - 9-12 weeks, 10-12 weeks, 10 wks-13wks 6 days

uses/results: detects 99% of chrom abnormalities, biochem/dna(single gene)/chrom analysis, cannot id single gene disorders unless have a gene marker, mosaicism, birth defects seen before 10 weeks gestation, miscarriage 1%

1/200 risk - about the same as amniocentesis because babies die in between cvs time and amnio time

sample amniotic fluid
SCREENS for NTD's, ultrasound is DIAGNOSTIC

Timing - 15-24 weeks 16-20, SECOND TRIMESTERS

uses/results - chrom/dna/biochem analysis (including AFPlevels. highlevels = ONTD screening, low = trisomies) , 99% of chrom abnormalities

miscarriage 1/200, transmit hiv, rh isoimmunozation
PUBS percutaneous umbilical blood sampling

sample umbilical vein for fetal blood

timing - after 18 weeks
Uses - diagnostic and therapeutic, in utero infection, karyotype, Rh incompatability
if you have a downs syndrome child what is your risk of having another?
1%, 1/100, so offer amnio/cvs
what is the risk if you have 14/21 translocation of having downs?
mother - 10/15% empiric risk, so offer cvs/amnio
35 women at 6 weeks gestation, what would you suggest?
offer CVS(need really high skilled operator), offer AFP with CVS cause dont get NTD detection, or amniocentesis
22 year old woman with no sig history
FIRST, or maternal serum screen

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