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Screening for cystic fibrosis: a four year regional experience
G Roberts1, M Stanfield, A Black
1Department of Clinical Biochemistry, Royal Victoria Hospital, Belfast.
Insights
A regional screening program for cystic fibrosis (CF) using immunoreactive trypsinogen detected 60 infants. Despite false positives/negatives and low sweat sodium in some cases, screening enables earlier CF diagnosis and genetic counseling.
Area of Science:
- Medical Screening
- Pediatric Medicine
- Genetic Disorders
Background:
- Cystic fibrosis (CF) is a genetic disorder requiring early detection for optimal management.
- Neonatal screening programs aim to identify infants with CF at birth.
- Immunoreactive trypsinogen (IRT) is a common biomarker used in CF screening.
Purpose of the Study:
- To describe the outcomes of a four-year regional screening program for cystic fibrosis.
- To evaluate the effectiveness and challenges of using immunoreactive trypsinogen (IRT) for CF detection in infants.
- To determine the incidence of CF in the screened region.
Main Methods:
- Implementation of a regional screening program over four years.
- Measurement of immunoreactive trypsinogen (IRT) levels in infants.
- Diagnosis confirmation through clinical assessment, meconium ileus observation, and sweat testing.
Main Results:
- Sixty infants were diagnosed with cystic fibrosis during the study period.
- 34 cases were identified via screening, 12 by meconium ileus, and 14 presented later with symptoms.
- The incidence of cystic fibrosis in the region was determined to be 1/1807.
- The screening assay exhibited false positives and false negatives.
- Eight infants with confirmed CF had low sweat sodium concentrations (<70 mmol/l), particularly notable in very young infants.
- 20% of screened infants were asymptomatic at diagnosis, while others had subtle symptoms missed by screening.
Conclusions:
- Regional screening for cystic fibrosis using IRT facilitates earlier diagnosis and intervention.
- The IRT screening assay has limitations, including false positives and negatives.
- Low sweat sodium levels can occur in infants with CF, necessitating careful interpretation.
- Despite challenges, the continuation of the cystic fibrosis screening program was recommended.
Abstract:
A four year regional screening programme to detect cystic fibrosis using measurement of immunoreactive trypsinogen is described. During this period 60 infants were diagnosed; 34 by screening, 12 born with meconium ileus, and 14 not identified by the screening assay but who presented with clinical symptoms at a later age, giving an incidence of cyst fibrosis in the region during this time of 1/1807. Screening has resulted in earlier detection of cystic fibrosis in many infants, thus allowing treatment to be instituted at an early age, and genetic counseling offered to the parents. There were a number of false positives and false negatives with the immunoreactive trypsinogen screening assay. In addition, eight infants who were sweat tested at an early age had a sweat sodium concentration of less than 70 mmol/l, although they were subsequently shown to have cystic fibrosis. These results confirm other published data showing that sweat sodium results may be low in very young infants with cystic fibrosis. At the time of diagnosis seven (20%) of the infants identified by screening were totally asymptomatic and several additional children had symptoms of such a type that the diagnosis of cystic fibrosis had not been considered at the time of screening. Despite the problems experienced it has been decided to continue screening.