Suppressor of lin-12-like–HMG-CoA reductase degradation 1 (SEL1L-HRD1) ER-associated degradation (ERAD) plays a critical role in many physiological processes in mice, including immunity, water homeostasis, and energy metabolism; however, its relevance and importance in humans remain unclear, as no disease variant has been identified. Here, we report a biallelic SEL1L variant (p. Cys141Tyr) in 5 patients from a consanguineous Slovakian family. These patients presented with not only ERAD-associated neurodevelopmental disorders with onset in infancy (ENDI) syndromes, but infantile-onset agammaglobulinemia with no mature B cells, resulting in frequent infections and early death. This variant disrupted the formation of a disulfide bond in the luminal fibronectin II domain of SEL1L, largely abolishing the function of the SEL1L-HRD1 ERAD complex in part via proteasomal-mediated self destruction by HRD1. This study reports a disease entity termed ENDI-agammaglobulinemia (ENDI-A) syndrome and establishes an inverse correlation between SEL1L-HRD1 ERAD functionality and disease severity in humans.
Denisa Weis, Liangguang L. Lin, Huilun H. Wang, Zexin Jason Li, Katarina Kusikova, Peter Ciznar, Hermann M. Wolf, Alexander Leiss-Piller, Zhihong Wang, Xiaoqiong Wei, Serge Weis, Katarina Skalicka, Gabriela Hrckova, Lubos Danisovic, Andrea Soltysova, Tingxuan T. Yang, René Günther Feichtinger, Johannes A. Mayr, Ling Qi
Summary and comparison of clinical features of 5 ENDI-A and 6 ENDI patients described in the accompanying paper