Primary immunodeficiency diseases (PIDs) patients may show systemic lupus erythematosus (SLE)-like autoimmunity disorders, such as cytopenias, as well as polyarthritis, which leads to concerns of misdiagnosis. We diagnosed three RALD cases between 2015 and 2018, who were suspected as SLE and summarized clinical characteristics.

We collected and analyzed the clinical data of the 3 cases. DNA was extracted from the patients’ and their parents’ peripheral blood as well as oral mucosa cells, hair follicles, and nails. Genes were detected with the application of gene trapping high-throughput sequencing using PIDs panel and suspicious gene or mutation was further verified by Sanger sequencing.

1. Clinical features: On the one hand, the patients presented with severe thrombocytopenia, facial erythema, arthritis, positive autoantibodies and other manifestations, supporting the diagnosis of SLE. On the other hand, symptoms including early onset ages, recurrent infections, lymphadenopathy, hepatosplenomegaly, monocytosis and hypergammaglobulinemia, were common observed in PIDs.

2. Gene analysis: NRAS mutations (c.38G > A, p.G13D or c.37G > T, p.G13C) were found in the blood of the patients. Besides, the same set of mutations was detected in buccal mucosa of patient 1 and nails of patient 3 while the frequency was much lower. However, no mutation was found in other tissues or in their parents’ blood. Consequently, they were NRAS somatic mutated RALD.

For those early-onset SLE-like patients with predominant hematologic disorders, monocytosis, recurrent infectious history, accompanied with hepatosplenomegaly and lymphadenopathy, a genetic screening of PIDs might be required.