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37 Cards in this Set
- Front
- Back
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What's the difference between X-linked recessive and Xlinked dominant syndromes?
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X-linked recessive are passed from Mom to her sons (50% sons), while X-linked dominant syndromes can be passed from any parent to the kid (behave like autosomal dominant syndrome)
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What is the median age of survical for a CF patient?
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30 years
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What is the biggest problem with current CF screening techniques?
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Not all alleles have been identified so some pts can go undetcted
(relatively high fale negative rate) |
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Two ethnic groups affected by Tay-Sachs:
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Eastern European Jews, French Canadians
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What is the founder effect?
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Happens in diseases such as Tay-Sachs where there is a super high frequency of a mutant allele, and it is usually due to the one or more of the founders of an ancestral group carrying the mutation
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At one age does Tay-Sachs typically present?
What are the signs and symptoms? |
3-10 months
Loss of alertness with an excessive reaction to noise as well as general neurologic degeneration. Classic finding is Cherry-red spots. Most die by age 4 |
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MBM review!!! What is the pathophysiology behind Tay-Sacchs?
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Deficiency of hexosaminidase resu.ts in increase in gangliosides. Failure to clear these results accumulations (especially in brain) which lead to cellular dysfunction.
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What is the basic pathophysiology behind thalassemias?
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Impaired production in either the alpha or beta chains of Hgb.
Unpaired globins precipitate and cause damage to membranes and extravascular hemolysis. |
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Why are beta thalassemias not usually diagnosed until several months after birth?
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Because the fetus doesn't need the beta chain.
The gamma chain serves as a substitute. |
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While heterozygotes of beta-thalassemia have any abnormal lab findings?
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Yes!
They will show a mild hemolytic anemia and low MCV |
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Will severe Alpha Thalassemias have any fetal hemoglobin (HbF)?
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No!
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What are the components of the triple screen? What's the fourth component that makes up a quad screen?
This is a K-N-O-W |
MSAFP
Estriol Beta-hCG Inhibin A (fourth component) |
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What is the false negative rate for using ultrasound to pick up fetal abnormalities in Down Syndrome?
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About 40-50% will be missed
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What are the components of a first trimester screen for Down's syndrome?
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Ultrasound for Nuchal translucency, Free Beta-hCG, and PAPP-A
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What are the defects associated with Trisomy 18 (Edward syndrome)?
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Clenched fists with overlapping digits
Rocker bottom feet VSD Tetralogy of Fallot Omphalocele Congenital diaphragmatic hernia Neuro tube defects Choroid plexus cysts |
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What are the defects associated with Trisomy 13 (Pata Syndrome)?
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Holoprosencephaly
Cleft lip / palate Cystic hygroma Absent nose Hypoplastic left heart Limb anomalies |
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Dyscribe the pertinent physical exam findings you may see in a patient with Turners:
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Webbed neck, low-set ears, shield-like chest, wide setnipples, renal problems, lymphedema, coarctation of the aorta (won't seen that on physical)
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What is the prime weeks for organogenesis?
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Third to eighth week gestation
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"Lemon" sign and "Banana" sign are associated with what congenital defect?
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Neural tube defect
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How do neural tube defects affect the MSAFP?
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They increase the level
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In which week does the heart begin to form?
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3rd week
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What is Potter Syndrome?
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Renal failure leading to anhydramnios, which in turn causes pumonar hypoplasia and contractures.
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In which week do the kidneys begin to form?
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Week 4
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How do you calculate the positive predictive value?
What does the PPV tell us? |
True positives divided by (True positives + False positives)
Tells us what percentage of people who have a positive screen will actually have the disease |
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How do you calculate the negative predictive value?
Whad does the NPV tell us? |
True negatives divided by (True negatives + False negatives )
Tells us what percentage of people who test negative will actually be negative for a disease |
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Would you expect to find a high or low serum estriol in a fetus with Down Syndrome?
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Low esriol
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Would you expect to find a high or low serum B-hCG in a fetus with Down Syndrome?
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High b-hCG
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What is the sensitivity of a combined PAPP-A + free B-HCG in the first trimester screening for Down Syndrome?
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Approaches 80%
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What are some common reasons why a MSAFP will be elevated (other than NTDs)?
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Inaccurate dating, abdominal wall defects, multiple gestations, fetal demise
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Will the Beta HCG be elevated or decreased in a fetus with Trisomy 18?
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Decreased
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Why must you wait beyond 15 weeks to obtain an amniocentesis?
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Because this is when the chorion and amnion have fused
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What is the complication rate of amniocentesis?
What are the major complications of amniocentesis? |
1/200
Maor complications include preterm labor, fetal injury, PPROM |
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At what gestational age can you start offer Chorionic Villous Sampling (CVS)?
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Between 9 and 12 weeks
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What are the advantages and disadvantages of chorionic villous sampling versus amniocentesis?
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CVS can be performed earlier, and can get more cells to study, which results in faster results;
However, it is slightly more risky and, since you are going after placental cells and not fetal cells, the results may be obscured by placental mosaicism |
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What are some reasons why you would want to do fetal umbilical blood sampling (PUBS)
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Can check for hematocrit which is important for RH allimmunization and fetal anemia.
Also, you don't need to do any cultures at all (unlike CVS / amniocentesis) This also has therapeutic potential (for example blood transfusions to the fetus) |
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The fetal MRI is particularly good at studying which fetal organ?
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Fetal brain
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In which weeks do you specifically offer a level one ultrasound?
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Between 18 and 22 weeks.
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