ABCMdb

PMID: 20714932

Sommerburg O, Lindner M, Muckenthaler M, Kohlmueller D, Leible S, Feneberg R, Kulozik AE, Mall MA, Hoffmann GF
Initial evaluation of a biochemical cystic fibrosis newborn screening by sequential analysis of immunoreactive trypsinogen and pancreatitis-associated protein (IRT/PAP) as a strategy that does not involve DNA testing in a Northern European population.
J Inherit Metab Dis. 2010 Oct;33(Suppl 2):S263-71. Epub 2010 Aug 17., [PubMed]

Sentences

No. Mutations Sentence Comment

2 ABCC7 p.Gly551Asp ABCC7 p.Arg553* ABCC7 p.Gly542* Methods Prospective quantitation of PAP and genetic analysis for the presence of four mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene most prevalent in southwest Germany (F508del, R553X, G551D, G542X) were performed in all newborns with IRT> 99.0th percentile. Login to comment 58 ABCC7 p.Gly551Asp ABCC7 p.Arg553* ABCC7 p.Gly542* DNA analysis was performed for the four most common CFTR mutations in southwest Germany (F508del, R553X, G551D, G542X) (Lindner et al. 1992; Tummler et al. 1996) in parallel with biochemical analysis from the same dried blood spot. Login to comment 65 ABCC7 p.Gly551Asp ABCC7 p.Arg553* ABCC7 p.Gly542* IRT testing Mutation analysis F508del, R553X, G551D, G542X CF NBS positive, Recall for sweat testing NBS negative IRT > 99.0 P. no 1. Login to comment 77 ABCC7 p.Gly551Asp ABCC7 p.Gly542* These newborns were included in the study, and their samples were further analysed by measurements of PAP and CFTR mutation analysis. Out of these 632 IRT-positive newborns, 98 (0.13% of all newborns screened for CF) showed elevated PAP values, and 56 (0.08% of all newborns screened for CF) were positive in the genetic analysis. Out of these 56, homozygosity for F508del was detected in 6 cases, and 1 case was compound heterozygous for F508del /G542X and F508del /G551D. Login to comment 78 ABCC7 p.Gly551Asp ABCC7 p.Gly542* In the remaining 48 newborns, one mutation was found in 39 (36 F508del, 2 G551D, and 1 G542X) and 9 newborns had initial results which were inconclusive because PCR amplification of DNA from dried blood spots on Guthrie cards failed. Login to comment 110 ABCC7 p.Gly551Asp ABCC7 p.Asn1303Lys ABCC7 p.Gly542* ABCC7 p.Ser1251Asn ABCC7 p.Gln552* ABCC7 p.Arg709* ABCC7 p.Glu664* In the second column, the results for both screening strategies are given CF patient True result for PAP/DNA Meconium ileus IRT (ng/ml) PAP (ng/ml) initial DNA result Age at referral (weeks) Mean of sweat Cl- measures (mmol/l) Age at diagnosis (weeks) Subsequent investigation Further DNA analysis 1 FN/FN No 36.0 n.d. n.d. 10 84 12 No special F508del/S1251N 2 TP/TP No 95.5 2.56 F508del/G542X 5 84 6 No special n.d. 3 TP/TP No 132.5 5.81 F508del/ - 4 95 5 No special n.d.a 4 TP/FN No 152.5 2.70 - / - 8b 44 10 ICMc CFTRdele2,3/ - c 5 TP/TP No 204.0 1.00 F508del/G551D 6 95 6 No special n.d. 6 TP/TP Yes 245.0 1.00 F508del/F508del - n.d.d 1 No special n.d. 7 TP/TP No 220.5 1.70 F508del/F508del 8b 82 10 No special n.d. 8 FN/FN No 139.0 0.95 - / - 15b 93 16 No special N1303K/R709X 9 TP/TP Yes 197.5 1.20 F508del/F508del - n.d.d 1 No special n.d. 10 TP/TP Yes 143.5 1.10 F508del/F508del - 92 1 No special n.d. 11 TP/TP No 114.0 1.45 F508del/ - 7b 116 7 No special F508del/p.Q552X 12 TP/TP No 174.5 2.60 F508del/F508del 4 88 5 No special n.d. 13 TP/TP Yes 81 1.30 F508del/F508del 1 n.d.d 1 No special n.d. 14 TP/FN No 198.5 9.45 - / - 8b 103 8 No special CFTRdele2,3/ E664X PAP IRT/PAP strategy, DNA IRT/DNA strategy, TP true positive, FN false negative a Further DNA analysis was not performed in the local CF centre after the health insurance of the patient refused to pay for further DNA analysis. Login to comment 117 ABCC7 p.Gly551Asp ABCC7 p.Arg553* ABCC7 p.Gly542* Values for IRT/PAP are given for the cut-off value of ≥1.0 ng/mL used in this study and extrapolated for cut-off value of >0.9 ng/mL Patient group Number Newborns screened for CF (April 2008- November 2009) 73,759 CF patients detected (including failsafe protocol) 13 CF patients not detected (missed by all protocols) 1 Prevalence 1: 5268 (2,857-9,493) Screening strategy IRT/DNA (p.F508del, p.G551D, p.R553X, p.G542X) IRT/PAP (cut-off ≥1.0 ng/mL) IRT/PAP (suggested cut-off >0.9 ng/mL) Detected CF patients 10 12 13 False negative results 4 2 1 False positive results 46 86 99 Sensitivity 0.714 (0.478-0.951) 0.857 (0.674-0.999) 0.928 (0.794-0.999) Specificity 0.999 (0.999-0.999) 0.999 (0.998-0.999) 0.999 (0.998-0.999) Positive predictive value 0.179 (0.078-0.278) 0.122 (0.058-0.187) 0.116 (0.057-0.175) Negative predictive value 0.999 (0.999-0.999) 0.999 (0.999-0.999) 0.999 (0.999-0.999) 50 100 150 200 250 300 0 1 2 3 4 5 6 7 8 9 10 Non-CF CF Cut-off 1.0 ng/ml a IRT [ng/ml] PAP[ng/ml] Non-CF CF 0 1 2 3 b 9 10 11 p < 0.02 p < 0.0001 Non-CF carriers PAP[ng/ml] Fig. 3a, b Relationship between IRT and PAP concentrations and summary of PAP concentrations in non-CF and CF newborns. Login to comment 144 ABCC7 p.Ser1251Asn Subsequent CFTR mutation analysis demonstrated that this patient was compound heterozygous for two disease-causing mutations (F508del and IRT/PAP positive 98 IRT/DNA positve 56 CF-Patients found 13 10 1 2 0 non-CF carriers 35 3 32 78 5 6 Fig. 4 Venn diagram illustrating infants who tested positive with IRT/ PAP and/or IRT/DNA, the distribution of the infants diagnosed with CF, and the distribution of non-CF carriers S1251N) and is therefore expected to develop a classical CF phenotype (Kalin et al. 1992). Login to comment 148 ABCC7 p.Asn1303Lys ABCC7 p.Arg709* One of these CF infants was also missed by the IRT/PAP strategy but was identified by the failsafe protocol that depended on IRT concentrations >99.9th percentile, and mutation analysis revealed compound heterozygosity for N1303K and R709X indicating that the patient will develop classical CF. Login to comment