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14 Cards in this Set
- Front
- Back
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Cystic Fibrosis: Clinical Features
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Chronic pulmonary disease
Exocrine pancreatic insufficiency Failure to thrive, meconium ileus in infants Sinusitis, nasal polyps Infertility in males Elevated sweat electrolyte levels |
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Laboratory Diagnosis and Screening of Cystic Fibrosis
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Sweat testing
Immunoreactive trypsin test (IRT) DNA analysis |
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Cystic Fibrosis Carrier Frequencies in Various American Ethnic/Racial Populations
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European Caucasian=1/29
Ashkenazi Jewish=1/29 Hispanic American=1/46 African American=1/65 Asian American=1/90 |
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The Cystic Fibrosis Gene: Vital Statistics
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Complete gene locus spans 250 kb
27 exons Mature mRNA of 6500 bases Encodes an ion channel of 1480 amino acids (CFTR) Three-nucleotide deletion of codon 508 (phe) in 70% |
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Delta F508
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Shorthand for CF
Deletion+ Phenylalenine +codon # |
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most common recessive leathal disorder in North America
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CF
Deletion+ Phenylalenine +codon # |
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about 24 possible mutations with CF
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diversity of mutations
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ETHICAL ISSUES IN CYSTIC FIBROSIS MUTATION SCREENING
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Suboptimal test sensitivity
Ethnic differences Education and counseling Anxiety and stigmatization Informed consent Confidentiality Insurability Genetic and clinical burden Abortion |
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R117H CF mutation
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This mutation just causes male infertility
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Preimplantation Genetic Diagnosis
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Know mutation in both man & woman – start until blastocyst- test cell – implant in mom if negative – if positive throw out blastocyst
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Potential Specimen Sources for Preimplantation Diagnosis
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Spermatozoa
Oocytes First polar body Early embryonic cleavage cells Blastomeres |
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NIH 1997 press release
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Testing for CF should be offered to all pregnant couples
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With 2 CF carrier parents what are the chances of:
1)Unaffected non-carrier 2)Unaffected carrier 3)Affected |
1)25%
2)50% 3)25% |
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SUMMARY OF ACMG RECOMMENDATIONS FOR POPULATION-BASED CYSTIC FIBROSIS CARRIER SCREENING
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1. Testing should be offered to Caucasians and Ashkenazi Jews, and made available to all other ethnic groups.
2. Either simultaneous or sequential couple screening may be used, as long as results are given to both partners. 3. A universal, pan-ethnic core mutation panel should be used, consisting of: - 25 mutations - 3 exonic polymorphisms as reflex tests - 5/7/9T intronic polymorphism as reflex test only if R117H is positive |
