RESUMO
We used a three-tier neonatal screening method for cystic fibrosis disease. A total of 924 newborns, 458 males and 466 females, were screened by taking a heel prick on Guthrie cards during the first, three days after labour. The studied newborns were divided into two groups: Group I included forty high risk neonates and Group II included 884 randomized full term neonates. For all 942 newborns immunoreactive trypsinogen [IRT] was determined in neonatal blood spot. Forty positive cases [IRT equal to or higher than 60 ng/mL] were confirmed by sweat electrolyte testing. It was positive [equal to or higher than 50 mEq/L] in only three cases. DNA analysis using ARMS-PCR amplification technique for detection of F508 mutation was done to the three positive infants. One did not show the F508 mutation on both allels. The other two carried the F508 mutation on one allele. All three cases were recalled to exclude CF disease