ACK1 and BRK non-receptor tyrosine kinase deficiencies are associated with familial systemic lupus and involved in efferocytosis

Systemic Lupus Erythematosus (SLE) is an autoimmune disease, the pathophysiology and genetic basis of which are incompletely understood. Non-receptor tyrosine kinases (NRTKs) regulate activation, migration, and proliferation of immune cells. We report compound heterozygous deleterious variants in the kinase domains of the non-receptor tyrosine kinases (NRTK) TNK2/ACK1 in one multiplex family and PTK6/BRK in another. Experimental blockade of mouse ACK1 or BRK increases glomerular IgG deposits and circulating autoantibodies in an in vivo SLE model. In addition, we found that the patients’ ACK and BRK variants impair efferocytosis, the MERTK-mediated anti-inflammatory response to apoptotic cells, in human induced Pluripotent Stem Cells (hiPSC)-derived macrophages. Overall, our data suggest that ACK1 and BRK deficiencies are associated with human SLE and impair efferocytosis.