Objective: Type D personality, characterized by negative affectivity and social inhibition, has been associated with increased psychological distress and reduced quality of life in individuals with chronic illnesses. This study aimed to determine the prevalence of Type D personality and examine its psychosocial correlates in adults diagnosed with inborn errors of immunity (IEI).

Materials and Methods: This descriptive, cross-sectional study included 53 adult patients with IEI. Sociodemographic, clinical, and psychosocial data were collected using a structured patient identification form. Type D personality was assessed using the validated Turkish version of the Type D Scale-14 (DS14). Group comparisons were performed using appropriate statistical tests.

Results: Type D personality was identified in 22.6% of participants (n = 12). It was more prevalent among women (27.6%) than men (16.7%) (p = 0.344). Higher rates were observed among divorced (42.9%) and single (35.3%) participants compared to married individuals (10.3%) (p = 0.062), among unemployed (32.1%) versus employed participants (12.0%) (p = 0.080), and among those reporting nicotine and/or alcohol use (33.3%) compared to non-users (11.5%) (p = 0.099). Participants with a psychiatric diagnosis had significantly higher rates of Type D personality compared to those without (57.1% vs. 17.4%, p = 0.039). No significant associations were identified with clinical parameters.

Conclusion: In this cohort of adult patients with IEI, the prevalence of Type D personality was comparable to that reported in general population samples, but significantly higher among individuals with a psychiatric diagnosis, suggesting a potential link between Type D traits and psychological vulnerability in this group.