Neonatal Cystic Fibrosis Screening in Latvia: A Pilot Project

Cystic fibrosis (CF) is one of the most common severe autosomal recessive diseases in the Northern European population affecting 1:2000-4000 individuals worldwide and 1:3300 in Latvia. Every year in Latvia since 1994, the approximate birth rate is 20,000 newborns per year, so theoretically there should be 6-8 new cases of CF per year. In Latvia, since 1998, there have been 49 patients with clinically confirmed diagnosis of CF. Recognition of a person with cystic fibrosis has always been a challenging task for clinicians, because of the constellation of symptoms, which can easily be misleading and explained by other aetiology. Therefore, in several countries, neonatal screening programmes using immunoreactive trypsinogen (IRT) have been introduced. The aim of this study was to evaluate the possible introduction of a neonatal IRT and DNA screening programme for diagnostic confirmation of cystic fibrosis in Latvian infants. IRT was measured in dried blood spots from 7,040 newborns, and DNA analysis for mutations dF508 and 394delTT performed for all individuals with increased IRT. Two persons suspected to have CF were identified, which is in accordance with population studies of CF frequency in Latvia. The estimated frequency of CF in Latvia of 1:3,520 corresponds to the average frequency in Europe. A mutation panel examining 230 mutations by APEX was applied to all samples with an IRT level above 100 ng/ml and two patients with the diagnosis of CF were identified. Cistiskā fibroze (CF) ir viena no biežākajām autosomāli recesīvajām slimībām, kas Ziemeļeiropas populācijā sastopama 1:2000-4000 personām, Latvijā tā sastopama 1:3300 personām. Kopš 1994. gada Latvijā katru gadu piedzimst apmēram 20 000 jaundzimušo, teorētiski sagaidāmais CF pacientu skaits ir 6-8, bet no 1998. gada Latvijā klīniski diagnosticēti 49 CF pacienti. CF nav raksturīgi specifiski simptomi, tāpēc slimības diagnostika sagādā grūtības. Vairākās valstīs ir ieviests jaundzimušo CF skrīnings. Projekta mērķis bija ieviest Latvijā CF jaundzimušo skrīningu, izmantojot imunoreaktīvā tripsinogēna (IRT) noteikšanu, ko papildina DNS diagnostika. IRT tika noteikts 7040 jaundzimušajiem, visiem ar paaugstinātu IRT līmeni veica dF508 un 394delTT mutāciju analīzi. Projekta rezultātā tika identificēti divi jaundzimušie dF508 heterozigoti, kas atbilst teorētiski sagaidāmai CF sastopamībai Latvijā un Eiropā 1: 3520. Pacientiem, kuriem IRT līmenis bija augstāks par 100 ng/ml, veica 230 mutāciju paneļa analīzi,