OB CF Screening

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Author:
choward04
ID:
221020
Filename:
OB CF Screening
Updated:
2013-05-24 20:15:44
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CF Screening
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Description:
OB Exam 2
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  1. ACOG/ACMG Recommendations CF Screening
    • All women of reproductive age
    • do not repeat if done earlier
    • NBS results (from previous pregnancy) does not replace maternal carrier screening
  2. ACOG/ACMG Affected Women
    • Affected women wants to become pregnant
    • -multidisciplinary team: PF, Wt gain, infections, DM & PTD risk
  3. ACOG/ACMG Both parents carriers
    refer to CG: review testing and reproductive options
  4. ACOG/ACMG Male with CF or isolated CBAVD
    Refer to GC: mutation analysis & consult
  5. ACOG/ACMG Unaffected parents, + FH
    Refer to GC & record review to ID mutations
  6. CF-Genetics
    • AR genetic disorder
    • Chrom 7
  7. CF Genetics
    Mutation classes
    • Class I-III most severe
    • ---non functioning chloride channels
    • Class IV-V milder forms
    • --at least some functioning chloride channels
  8. CF-Genetics
    • Most common single mutation
    • DeltaF508 (65-70% of cases
  9. CF Genetic Panel (2 types)
    Standard Panel (23) detects 75.3%

    Pan ethnic battery (64) more $$ detects 81.4%
  10. CF-Who is at risk in the US
    • All White: 1/2500 dis freq & 1/29 carrier (83%)
    • Ashkenasi Jew: 1/2300 dis freq & 1/29 carrier (97%)
    • Zuni & Pueblo Indian: 1/1580 & 1/3970 dis freq & 1/20 & 1/32 (? %) use Pan ethnic panel
    • Hispanic: 1/9200 & 1/52 (56.9%)
    • AA: 1/1500 & 1/61 (58%)
    • Asian: 1/37,000 & 1/96 (37.5)
  11. CF-Patho
    • Chloride ions pull water via osmotic gradient
    • --no channel= dehydration or obstruction
  12. CF-Patho
    Pulmonary: Dehydration
    • Upper airway-chronic sinusitis
    • Lower airway-thick, tenacious mucus, chronic cough, wheezing, frequent pneumonia and bronchitis
  13. CF-Patho 
    GI
    • Proenzymes unable to exit pancreatic ducts
    • early ongoing: fat malabsorption, poor weight gain, slowed linear growth
    • late (2nd decade and beyond)
    • gradual autodigestion of pancreas
    • CF-rtelated diabetes mellitus (CFRD)
  14. CF-Reproduction: Obstruction
    Male: CBAVD -may be only symptoms

    • Female: Thick mucus
    • ---impaired fall-decreased fallopian tube function-decreased fertility
    • --degree of pulmonary disease highly correlated to pregnancy
  15. Diagnosis-NB Screening Carrier Testing
    • Immune Reactive Trypsinogen (IRT)
    • Serum analyte that "seeps" into bloodstream when ducts obstructed¬†
    • Results-vary depending on institution (cut offs 90%) or abnormal as top 4-5% other 10% of daily values
  16. CF-Options (Screening/Testing)
    • Test pregnant woman and/or whoever has a the FH first
    • NEG= carrier risk reduced NOT zero
    • POS= testy partner-refer for GC
  17. CF-Both partner's positive
    • 1:4 chance child has disease
    • conduct:
    • pregestational diagnostic testing
    • prenatal diagnosis (amniocentesis, CVS)
    • cord blood
    • sweat chloride (>3 month of age)
  18. CF Testing Timing-A critical issue
    Maternal
    • Assume 10-14 days to obtain results
    • Maternal testing 15 weeks
    • Pos in 17 weeks
  19. CF Testing-Paternal
    • Paternal counseling/testing- 18 weeks
    • Positive results 20 weeks
  20. CF Genetic Counseling
    20+ weeks
  21. CF Amonicentesis
    • Test 21 weeks
    • Results: 23 weeks
  22. Take home CF test
    Ideally with new OB Labs
  23. CF-Diagnositc Testing
    • Clinical Sx's, NBS result or parental genetic status typically prompt testing
    • 1. DNA-based=genotype (amnio, cord, serum)
    • 2. Sweat chloride=phenotype (<3 months may be false neg)
  24. CF-Genetic Counseling Critical Point
    Reduces the chance that a patient is a carrier but cannot totally exclude it
  25. CF Carrier Risk
    Both Parents carry CF mutation
    Risk of offspring w mutation 1:4 or 25%
  26. CF Carrier Risk
    One Parent has CF and one is carrier
    • All offspring have at least 1 mutation
    • -risk for having an offspring carrier 2:4 or 50%
    • -risk for having an affected offspring 2:4 or 50%
  27. CF Carrier Risk
    One parent is a carrier, partner status unknown
    • --known carrier (1:1 risk of carrier status)
    • --assume partner at high risk (1:29 risk)

    • math: 1:1x1:29=1:29x1:1:4=1:116 risk affected offspring
    • JUSTIFIES Amnio risk
  28. CF Carrier Risk
    One parent has SIBLING with CF, parent status unknown
    What is the parents risk of being a carrier
    • --they are not affected
    • --their risk of being a carrier 2:3 or 66%
  29. CF Carrier Risk
    One parent has a NEICE/NEPHEW with CF
    Don't know their status
    What is risk of being carrier
    Their risk of being carrier 2:4 or 50%
  30. CF Risk what all patients should know
    • What a recessive condition is?
    • What is CF?
    • Who is at risk?
    • Who is at lower risk?
    • What testing options are available?
    • Limitations of CF testing

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