Variable clinical presentation of hypomorphic DCLRE1C deficiency from childhood to adulthood.

Background: In this study, we aimed to report long‐term follow‐up of our pediatric and adult patients with DCLRE1C (DNA cross‐link repair 1C) hypomorphic mutation who were diagnosed leaky severe combined immunodeficiency (SCID). Methods: Eighteen patients (13 children and five adults), aged between 6 and 29 years were included. Clinical and immunological features, including immunoglobulin levels, T and B cells, natural killer cell subsets, regulator T (Treg) cell ratios/markers, and cytokines, were assessed before and after hematopoietic stem cell transplantation (HSCT) and compared with healthy controls. Results: Recurrent infections (78%) and skin manifestations (61%) such as granulomatous skin lesions, warts, and vitiligo were the most common clinical findings. Autoimmune diseases were observed in 33% and malignancy in 17%. Most patients had low serum IgA and B‐ and T‐cell lymphopenia at the first admission. Recent thymic emigrants (RTE), Tnaive, Bnaive, CD56dimCD16+ cell ratios were significantly lower in the patients than in control; however, follicular helper T TFH and Th1 [interferon gamma (IFN‐γ)] cell ratios were significantly higher than the control. Although, Treg ratio and its functional receptors tend to be high but not significant. Eleven patients (61.1%) were treated with HSCT. Median follow‐up times of transplant patients was 56 (9–67) months. Conclusion: Patients with hypomorphic DCLRE1C mutations may present with variable clinical and laboratory findings at different ages. Our study showed a helper T (Th)1‐dominant immune response before and after HSCT. Increased IFN‐γ and TFH cells ratio could be a reason of chronic inflammation and autoimmunity developing before and after HSCT. Long‐term follow‐up of these patients after HSCT will help to better understand the disease and its pathophysiology. [ABSTRACT FROM AUTHOR]