RT Journal Article
SR Electronic
T1 Measurement of nasal potential difference in young children with an equivocal sweat test following newborn screening for cystic fibrosis
JF Thorax
JO Thorax
FD BMJ Publishing Group Ltd and British Thoracic Society
SP 539
OP 544
DO 10.1136/thx.2009.123422
VO 65
IS 6
A1 Isabelle Sermet-Gaudelus
A1 Emmanuelle Girodon
A1 Delphine Roussel
A1 Eric Deneuville
A1 Stéphanie Bui
A1 Frédéric Huet
A1 Marcel Guillot
A1 Rola Aboutaam
A1 Michel Renouil
A1 Anne Munck
A1 Marie des Georges
A1 Albert Iron
A1 Christel Thauvin-Robinet
A1 Isabelle Fajac
A1 Gerard Lenoir
A1 Michel Roussey
A1 Aleksander Edelman
YR 2010
UL http://thorax.bmj.com/content/65/6/539.abstract
AB Background A challenging problem arising from cystic fibrosis (CF) newborn screening is the significant number of infants with hypertrypsinaemia (HIRT) with sweat chloride levels in the intermediate range and only one or no identified CF-causing mutations.Objectives To investigate the diagnostic value for CF of assessing CF transmembrane conductance regulator (CFTR) protein function by measuring nasal potential difference in children with HIRT.Methods A specially designed protocol was used to assess nasal potential difference (NPD) in 23 young children with HIRT (3 months–4 years) with inconclusive neonatal screening. Results were analysed with a composite score including CFTR-dependent sodium and chloride secretion. Results were correlated with genotype after extensive genetic screening and with clinical phenotype at follow-up 3 years later.Results NPD was interpretable for 21 children with HIRT: 13 had NPD composite scores in the CF range. All 13 were finally found to carry two CFTR mutations. At follow-up, nine had developed a chronic pulmonary disease consistent with a CF diagnosis. The sweat test could be repeated in nine children, and six had sweat chloride values ≥60 mmol/l. Of the eight children with normal NPD scores, only two had two CFTR mutations, both wide-spectrum mutations. None had developed a CF-like lung disease at follow-up. The sweat test could be reassessed in five of these eight children and all had sweat chloride values <60 mmol/l. CF diagnosis was ruled out in six of these eight children.Conclusion Evaluation of CFTR function in the nasal epithelium of young children with inconclusive results at CF newborn screening is a useful diagnostic tool for CF.