Prospective and parallel assessments of cystic fibrosis newborn screening protocols in the Czech Republic: IRT/DNA/IRT versus IRT/PAP and IRT/PAP/DNA.

UNLABELLED: Cystic fibrosis (CF) is a life-threatening disease for which early diagnosis following newborn screening (NBS) improves the prognosis. We performed a prospective assessment of the immunoreactive trypsinogen (IRT)/DNA/IRT protocol currently in use nationwide, versus the IRT/pancreatitis-associated protein (PAP) and IRT/PAP/DNA CF NBS protocols. Dried blood spots (DBS) from 106,522 Czech newborns were examined for IRT concentrations. In the IRT/DNA/IRT protocol, DNA-testing was performed for IRT ≥ 65 ng/mL. Newborns with IRT ≥ 200 ng/mL and no detected cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations were recalled for a repeat IRT. In the same group of newborns, for both parallel protocols, PAP was measured in DBS with IRT ≥ 50 ng/mL. In PAP-positive newborns (i.e., ≥1.8 if IRT 50-99.9 or ≥1.0 if IRT ≥ 100, all in ng/mL), DNA-testing followed as part of the IRT/PAP/DNA protocol. Newborns with at least one CFTR mutation in the IRT/DNA/IRT and IRT/PAP/DNA protocols; a positive PAP in IRT/PAP; or a high repeat IRT in IRT/DNA/IRT were referred for sweat testing. CONCLUSION: the combined results of the utilized protocols led to the detection of 21 CF patients, 19 of which were identified using the IRT/DNA/IRT protocol, 16 using IRT/PAP, and 15 using IRT/PAP/DNA. Decreased cut-offs for PAP within the IRT/PAP protocol would lead to higher sensitivity but would increase false positives. Within the IRT/PAP/DNA protocol, decreased PAP cut-offs would result in high sensitivity, an acceptable number of false positives, and would reduce the number of DNA analyses. Thus, we concluded that the IRT/PAP/DNA protocol would represent the most suitable protocol in our conditions.

Pilot newborn screening project for cystic fibrosis in the Czech Republic: defining role of the delay in its symptomatic diagnosis and influence of ultrasound-based prenatal diagnosis on the incidence of the disease.

The objective need for cystic fibrosis (CF) newborn screening (NBS) in the Czech Republic has recently been substantiated by a significant delay of its symptomatic diagnosis. This trend most likely resulted from the process of decentralisation of health care which led to the deterioration of care for patients who need specialised approaches. Applied newborn screening model (IRT/DNA/IRT) was efficacious enough to detect CF cases with median age at diagnosis of 37 days. The incidence of CF (1 in 6946 live births) ascertained in this project was lower than that established previously by epidemiological studies (1 in 2700-1 in 3300). However, adjustment for broadly applied ultrasound-based prenatal diagnosis (PND) in the 2nd trimester of pregnancy, that was performed within the period of the project (1/2/2005-2/11/2006), rendered an incidence estimate of 1 in 4023. This value is closer to that observed in other CF NBS programmes and reflects influence of PND on the incidence of CF.