Blood concentrations of pancreatitis associated protein in neonates: Relevance to neonatal screening for cystic fibrosis

Abstract

Aim - To determine whether pancreatitis associated protein (PAP) is a marker for cystic fibrosis which could be used in neonatal screening for the disease. Methods - PAP was assayed on screening cards from 202 807 neonates. Babies with PAP ≥ 15 ng/ml, or ≥ 11.5 ng/ml and immunoreactive trypsinogen (IRT) ≥ 700 ng/ml were recalled for clinical examination, sweat testing, and cystic fibrosis transmembrane regulator (CFTR) gene analysis. Results - Median PAP value was 2.8 ng/ml. Forty four cases of cystic fibrosis were recorded. Recalled neonates (n=398) included only 11 carriers. A receiver operating characteristic curve analysis showed that PAP above 8.0 ng/ml would select 0.76% of babies, including all those with cystic fibrosis, except for one with meconium ileus and two with mild CFTR mutations. Screening 27 146 babies with both PAP and IRT showed that only 0.12% had PAP > 8.0 ng/mi and IRT > 700 ng/ml, including all cases of cystic fibrosis. Conclusion - PAP is increased in most neonates with cystic fibrosis and could be used for CF screening. Its combination with IRT looks promising.