Second Screening for Celiac Disease in First-Degree Relatives of Pediatric Index Cases: A Single-Center Observational Study.

Objective: This study investigated new seropositivity detected during repeat screening among first-degree relatives of pediatric index cases with celiac disease (CD) who were seronegative at initial screening. Materials and Methods: This single-center, observational, family-based screening study was conducted at a tertiary pediatric gastroenterology center. First-degree relatives of 117 pediatric index cases with biopsy-confirmed CD were invited for screening. CD screening was performed using tissue transglutaminase immunoglobulin A, with tissue transglutaminase immunoglobulin G used in cases of low total immunoglobulin A. Individuals with seropositivity underwent upper gastrointestinal endoscopy with duodenal biopsy. Histopathologic findings were evaluated according to the Marsh classification. Among participants with negative initial serology, those whose first screening had been performed at least 1 year earlier underwent repeat serologic screening. Results: Of the 462 invited first-degree relatives, 376 participated in the initial screening. Seropositivity was detected in 5.6% of participants, and biopsy-confirmed CD was established in 5.0%. Among the 355 individuals with negative initial serology, 101 underwent repeat screening after a median interval of 3.0 years. New seropositivity was detected in 4 of these 101 individuals [3.9%; exact binomial 95% CI: 1.1-9.8], and all had biopsy-confirmed CD. Three of the newly identified cases were siblings who had been screened in early childhood. No significant association was found between the presence of symptoms and serologic positivity at either screening. Conclusion: First-degree relatives of pediatric patients with CD represent a high-risk group in whom new seropositivity may emerge over time. Repeat screening, particularly in relatives first screened during early childhood, may improve case detection.