Primary immune regulatory disorders (PIRDs) are a group of conditions characterised by a loss of immune tolerance. Two such disorders, CHAI and LATAIE, share common molecular mechanisms, leading to significant clinical overlap. Here, we report demographic, clinical, immunological, and molecular findings in 29 patients referred from different parts of India with a diagnosis of CHAI or LATAIE. LATAIE patients demonstrated a higher prevalence of consanguinity, while CHAI patients more often had a positive family history. Both disorders presented with overlapping clinical features, predominately autoimmune cytopenias, benign lymphoproliferation, and inflammatory bowel disease (IBD). However, the incidence of recurrent infections, otitis media, bronchiectasis, and hypogammaglobulinemia was higher among LATAIE patients as compared to CHAI. Flow cytometry analysis revealed significant differences in T cell subsets, particularly in percentages of CD4+ naïve cells and T regulatory cells (Treg), between the two disorders. B cell abnormalities were also observed. Molecular diagnosis was achieved using targeted or clinical exome sequencing, and specific protein expression was employed to validate the novel variants.
Keywords: CTLA4; LRBA; PIRD; autoimmunity; flow cytometry; immunodeficiency; inborn errors of immunity.