[Mucoviscidosis screening of newborn infants in the Dresden district. Results from 1 June 1996 to 31 March 2000].

PROBLEM: Cystic fibrosis (CF) is the most common congenital defect of metabolism in Europe. Therefore we tried to detect this disease as early as possible before clinical symptoms occur. Thus early diagnosis can be the basis for an early start of treatment.

PATIENTS AND

METHODS

As part of a complete neonatal screening program in our region we investigated the concentration of immuno-reactive trypsin (IRT) in dried blood samples. Genomic investigation of the same blood sample for the most common CF mutations was performed when a critical value of IRT was exceeded.

RESULTS

From 6/1996 until 3/2000 (46 months) we investigated the blood of 49,926 newborn children. Due to a high IRT value (> 70 ng/ml) in 579 cases, a genomic investigation was performed. In 38 children we detected one of the three most frequent CF mutations (delta F508, G551D, R553X) by polymerase chain reaction (PCR). The sweat test (pilocarpine iontophoresis) confirmed cystic fibrosis in 8 newborns. Four times a homocygocity for the mutation delta F508 was found and four times a compound heterocygocity (one time delta F508/R553X und three times delta F508/others). Only three of these eight CF patients already had clinical symptoms of the disease at this time, only in one case had this diagnosis been considered. An additional newborn with meconium ileus had been diagnosed as cystic fibrosis before performing the screening. Up to now we have not found any case of false negative testing.

CONCLUSION

We found this procedure of neonatal testing practicable and therefore recommend its continuation. The genomic test should include the search for additional CF mutations. As alternative method a second IRT-test should be considered at the end of the first month of life for those children with initial IRT-concentrations above 150 ng/ml and without evidence of the three tested CFTR-mutations.