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CF Study Day - Cases. Martin J Schwarz. *. F508del / D1152H. F508del / D1152H. F508del / D1152H. D1152H / -. Asking the right question – doing the right test. Case 1 : the “Newborn Screening Incident”. * Previously seen for chronic cough; sweat test in the low 30s Cl -.
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CF Study Day - Cases Martin J Schwarz
* F508del / D1152H F508del / D1152H F508del / D1152H D1152H / - Asking the right question – doing the right test Case 1 : the “Newborn Screening Incident” *Previously seen for chronic cough; sweat test in the low 30s Cl-
Asking the right question – doing the right test Case 2 : the “ICSI phone call” F508del / T5 T5 / - - / - ? T5 (pat) / T5 (mat) F508del / T5 (mat) T5 (pat) / - F508del / - Carrier T5 Carrier F508del Possible symptoms? Possible symptoms? Possible lung disease Possible CBAVD in males?? – probably not (why not?) (See Groman et al (2004) Am. J. Hum. Genet. 74(1):176-9)
Point 2. Asking the right question – doing the right test Case 2 : the “Newborn Screening Incident” Questions arising : What is the purpose of screening? Should these mutations be included in the test panel? R117H (very variable, largely dependent on PolyT) D1152H (variable from ‘mild’ to CBAVD to late onset bronchiectasis) 3849+10kbC>T ( ditto ) Should sibs be tested after a positive diagnosis? Munck et al 2008 J.C.F.7(7); S13
The Decision Process (continued) Point 3. What are you going to do with the information you generate? • Sequencing the entire gene can reveal unwanted information • novel sequence changes • recurrent or identical by descent? • predictive value
The Decision Process (continued) Point 2. Ask the right clinical question • ?CF; CBAVD; bronchiectasis; echogenic bowel, etc • Is there a family history of CF? Are you just carrier testing? • Are the family relationships as stated?
A 9T/9T genotype would produce ~100% normal CFTR mRNA whereas ~~ a 5T/5T genotype produce ~10% (Chillon et al, 1995) 100% 9,9 7,9 7,7 PolyT haplotype % Full length transcript 5,9 5,7 5,5 0% Eric Alton’s gene therapy programme is aiming for “5% expression in 5% of cells”