Neonatal screening for cystic fibrosis in São Paulo State, Brazil: a pilot study.
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.
Departamento de Clínica Médica, Universidade de São Paulo.
R
R
Rodrigues
P K R
PK
Magalhaes
M I M
MI
Fernandes
C S
CS
Gabetta
A F
AF
Ribeiro
K P
KP
Pedro
F
F
Valdetaro
J L F
JL
Santos
R M de
RM
Souza
A
A
Pazin Filho
L M Z
LM
Maciel
D015415:Biomarkers / Q000097:blood; D001938:Brazil; D003550:Cystic Fibrosis / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods*; D010865:Pilot Projects; D011237:Predictive Value of Tests; D014362:Trypsinogen / Q000097:blood*
D015415:Biomarkers; D014362:Trypsinogen