Neonatal screening for cystic fibrosis in São Paulo State, Brazil: a pilot study

Author(s):Show less -

Rodrigues, R. ^[1] ; Magalhaes, P. K. R. ^[1] ; Fernandes, M. I. M. ^[2] ; Gabetta, C. S. ^[3] ; Ribeiro, A. F. ^[3] ; Pedro, K. P. ^[4] ; Valdetaro, F. ^[5] ; Santos, J. L. F. ^[6] ; de Souza, R. M. ^[6] ; Pazin Filho, A. ^[1] ; Maciel, L. M. Z. ^[1]

Affiliation

^[1] USP, Fac Med Ribeirao Preto, Dept Clin Med, BR-14049900 Ribeirao Preto, SP - Brazil

^[2] USP, Fac Med Ribeirao Preto, Dept Pediat, BR-14049900 Ribeirao Preto, SP - Brazil

^[3] Univ Estadual Campinas, Dept Pediat, Campinas, SP - Brazil

^[4] Associacao Pais & Amigos Excepsionais, Bauru, SP - Brazil

^[5] Hosp Santa Marcelina, Sao Paulo - Brazil

^[6] USP, Fac Med Ribeirao Preto, Dept Social Med, BR-14049900 Ribeirao Preto, SP - Brazil

• Document type: Journal article
• Source: Brazilian Journal of Medical and Biological Research; v. 42, n. 10, p. 973-978, OCT 2009.
• Web of Science Citations: 10

Abstract

Cystic fibrosis is one of the most common autosomal recessive hereditary diseases in the Caucasian population, with an incidence of 1:2000 to 1:3500 liveborns. More than 1000 mutations have been described with the most common being F508del. It has a prevalence of 23-55% within the Brazilian population. The lack of population-based studies evaluating the incidence of cystic fibrosis in São Paulo State, Brazil, and an analysis concerning the costs of implantation of a screening program motivated the present study. A total of 60,000 dried blood samples from Guthrie cards obtained from April 2005 to January 2006 for neonatal screening at 4 reference centers in São Paulo State were analyzed. The immunoreactive trypsinogen (IRT)/IRT protocol was used with the cut-off value being 70 ng/mL. A total of 532 children (0.9%) showed IRT >70 ng/mL and a 2nd sample was collected from 418 (80.3%) of these patients. Four affected children were detected at two centers, corresponding to an incidence of 1:8403. The average age at diagnosis was 69 days, and 3 of the children already showed severe symptoms of the disease. The rate of false-positive results was 95.2% and the positive predictive value for the test was 8%. The cost of detecting an affected subject was approximately US$8,000.00 when this cystic fibrosis program was added to an existing neonatal screening program. The present study clearly shows the difficulties involved in cystic fibrosis screening using the IRT/IRT protocol, particularly in a population with no long-term tradition of neonatal screening. (AU)