RESUMEN
Mutations in several proteins functioning as endolysosomal components cause monogenic autoimmune diseases, of which pathogenesis is linked to increased endoplasmic reticulum stress, inefficient autophagy, and defective recycling of immune receptors. We report here a heterozygous TOM1 p.G307D missense mutation, detected by whole-exome sequencing, in two related patients presenting with early-onset autoimmunity, antibody deficiency, and features of combined immunodeficiency. The index patient suffered from recurrent respiratory tract infections and oligoarthritis since early teens, and later developed persistent low-copy EBV-viremia, as well as an antibody deficiency. Her infant son developed hypogammaglobulinemia, autoimmune enteropathy, interstitial lung disease, profound growth failure, and treatment-resistant psoriasis vulgaris. Consistent with previous knowledge on TOM1 protein function, we detected impaired autophagy and enhanced susceptibility to apoptosis in patient-derived cells. In addition, we noted diminished STAT and ERK1/2 signaling in patient fibroblasts, as well as poor IFN-γ and IL-17 secretion in T cells. The mutant TOM1 failed to interact with TOLLIP, a protein required for IL-1 recycling, PAMP signaling and autophagosome maturation, further strengthening the link between the candidate mutation and patient pathophysiology. In sum, we report here an identification of a novel gene, TOM1, associating with early-onset autoimmunity, antibody deficiency, and features of combined immunodeficiency. Other patient cases from unrelated families are needed to firmly establish a causal relationship between the genotype and the phenotype.
RESUMEN
The signal transducer and activator of transcription (STAT) family of transcription factors orchestrate hematopoietic cell differentiation. Recently, mutations in STAT1, STAT5B, and STAT3 have been linked to development of immunodysregulation polyendocrinopathy enteropathy X-linked-like syndrome. Here, we immunologically characterized 3 patients with de novo activating mutations in the DNA binding or dimerization domains of STAT3 (p.K392R, p.M394T, and p.K658N, respectively). The patients displayed multiorgan autoimmunity, lymphoproliferation, and delayed-onset mycobacterial disease. Immunologically, we noted hypogammaglobulinemia with terminal B-cell maturation arrest, dendritic cell deficiency, peripheral eosinopenia, increased double-negative (CD4(-)CD8(-)) T cells, and decreased natural killer, T helper 17, and regulatory T-cell numbers. Notably, the patient harboring the K392R mutation developed T-cell large granular lymphocytic leukemia at age 14 years. Our results broaden the spectrum of phenotypes caused by activating STAT3 mutations, highlight the role of STAT3 in the development and differentiation of multiple immune cell lineages, and strengthen the link between the STAT family of transcription factors and autoimmunity.
