Rare C1q deficiency presenting as pediatric SLE: A case study of two consanguineous siblings.

C1q deficiency is a rare autosomal recessive genetic condition characterized by mutations in genes C1qA, C1qB, or C1qC which can cause a SLE-like disease. Here, we report the cases of two siblings with C1q deficiency, both of whom had homozygous mutations in the C1QA gene. Both of our patients had NP involvement, and the brother had chilblain lesions. Diagnosis of C1q deficiency was delayed, highlighting the importance of clinical suspicion and genetic testing. This is especially crucial in cases with atypical presentations of SLE and a family history of consanguinity.