title: Cystic fibrosis newborn screening: distribution of blood immunoreactive trypsinogen concentrations in hypertrypsinemic neonates.
abstract: The IRT screening test for the use in diagnosing newborns with CF has a high sensitivity but is not very specific resulting in a large number of screened positive infants found to have a normal sweat test. The aim of this study was to analyze the differences in b-IRT levels among different groups of newborns positive to NBS.Population data included all b-IRT positive (>99th centile) neonates born in Lombardia from 2000 to 2007. The hypertrypsinemic newborns were divided into four groups, according to CF status (noncarrier, carrier, CFTR-RD, CF).Among a total of 717,172 newborns screened within the study period, 7,354 newborns were found positive to NBS and were included in the study. An overall statistically significant difference in b-IRT levels was found among the four groups (p < 0.001), while b-IRT values did not differ between noncarriers and carriers. b-IRT levels had a low predictive accuracy in correctly identifying the four different groups (c-index: 0.60), but the accuracy was high in discriminating between classic CF and carrier or noncarrier status in neonates positive to NBS. The IRT level on the initial blood specimen obtained at birth differs based on the CF genotype, although a wide range of individual variation may occur.
authors: Medical Genetics Laboratory, Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Via Commenda, 12, 20122, Milan, Italy.
authors: Valentina
authors: V
authors: Paracchini
authors: Manuela
authors: M
authors: Seia
authors: Sara
authors: S
authors: Raimondi
authors: Lucy
authors: L
authors: Costantino
authors: Patrizia
authors: P
authors: Capasso
authors: Luigi
authors: L
authors: Porcaro
authors: Carla
authors: C
authors: Colombo
authors: Domenico A
authors: DA
authors: Coviello
authors: Tiziana
authors: T
authors: Mariani
authors: Emanuela
authors: E
authors: Manzoni
authors: Monica
authors: M
authors: Sangiovanni
authors: Carlo
authors: C
authors: Corbetta