Objective: Micronucleus (MN) assay is considered as a useful and fast screening test to determine MN frequency indicating the chromosomal damage and instability. The aim of this study was to determine MN formation by using MN assay and fluorescence in situ hybridization (FISH) technique in patients with primary immunodeficiency (PID).

Materials and Methods: This study included fifteen patients with PID (5 with ataxia telangiectasia, 5 with common variable immunodeficiency, 3 with severe combined immunodeficiency and 2 with agammaglobulinemia) and 15 healthy age-matched children. Results: There was a significant increased MN frequency in cultured peripheral blood lymphocytes with Cyt-B in all patients (p< 0.05) when compared with the control group. When we compared the MN frequency among patients, the incidence of micronuclei (MNs) was found to be similar in cellular and humoral immunodeficiencies (IDs). However, the incidence of one-centromere-positive MNs was significantly higher in cellular IDs (p< 0.05).

Conclusion: In conclusion, the increased MN incidence and centromere positivity detected in PID diseases may be consistent with the chromosome instability, which contributes to the follow-up in these disorders.