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CF Case Studies Frances Bond West Midlands Regional Genetics Laboratory 15/10/08 SCOBEC & Birmingham Case Studies Training Day.

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Presentation on theme: "CF Case Studies Frances Bond West Midlands Regional Genetics Laboratory 15/10/08 SCOBEC & Birmingham Case Studies Training Day."— Presentation transcript:

1 CF Case Studies Frances Bond West Midlands Regional Genetics Laboratory 15/10/08 SCOBEC & Birmingham Case Studies Training Day

2 Cases Case 1- CM & AK –Echogenic bowel carrier testing referral Case 2 – RC –Meconium ileus diagnostic referral

3 Case 1 – CM & AK Pregnant women and partner –CF carrier tests - Echogenic bowel

4 Case 1 – CM & AK % of pregnancies Several causes including: –Normal variant - with no apparent cause Resolves itself with no known effect on the health of the child –Prenatal manifestation of meconium ileus ~11% of CF-affected foetuses ~1.3% of foetuses with echogenic bowel have CF –Can vary to up ~6% due to the subjectivity of diagnosing echogenic bowel Echogenic Bowel

5 Case 1 – CM & AK ARMS29 CM and AK both p. Phe508del heterozygotes Upper controls Lower controls p. Phe508del allele Normal allele at p. Phe508del locus

6 Case 1 – CM & AK At least 1 in 4 risk foetus affected with CF – Offer to test amniocentesis sample to determine CF status of foetus if required

7 Case 1 – CM & AK Amniocentesis sample tested to determine the CF status of the foetus –Unfortunately, MCC testing inconclusive Cultured amniocytes –ARMS29 assay: p. Phe508del heterozygote –No evidence of MCC Prenatal Test

8 Case 1 – CM & AK Foetus is a carrier of cystic fibrosis but is not predicted to be affected – Cytogenetic and QF-PCR results also negative – Sadly, foetus spontaneously aborted soon after

9 Case 2 - RC 8 day old male CF diagnosis test – meconium ileus

10 Case 2 - RC ARMS29 p. Phe508del and p. Arg117His compound heterozygote Upper controls Lower controls p. Arg117His allele p. Phe508del allele Normal allele at p. Phe508del locus

11 Case 2 - RC PolyT assay Effect of p. Arg117His mutation is modulated by size of polyT tract Heterozygous for 5T and 9T alleles 9T allele 5T allele 7T allele C = Control P = Patient RC

12 Case 2 - RC Interpretation –p.Phe508del muation always in cis with 9T allele –5T allele must be in cis with p.Arg117His Classical CF with pancreatic sufficiency

13 Case 2 - RC Not diagnosed as part of neonatal screening programme – Average IRT result: 64 – below cut-off for molecular analysis – IRT testing known to be inaccurate in cases with meconium ileus


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