Genetic workup as a complementary tool for the diagnosis of primary complement component deficiencies: a multicenter experience.

Diagnosis of primary complement deficiencies requires a high index of suspicion. Thus, susceptible patients are often underdiagnosed and untreated. Here, we present a multicenter experience with two novel inborn errors of the classical complement system. This is a retrospective multicenter analysis of computerized medical records of children (<18 years) admitted in the period between 2012 and 2018 at Shaare Zedek Medical Center in Jerusalem and Edmond and Lily Safra Children's Hospital, Tel-Hashomer Medical Center, in Ramat Gan, Israel. Patients were genetically diagnosed by a complementary immune workup. We identified 5 patients (3 males) from four different families harboring two novel mutations in the complement components C6-C8. Genetic mutations were identified by whole-exome sequencing or by sequencing of the coding exons of a single gene based on the findings in the immune workup. Clinical manifestations consisted of meningitis with or without meningococcemia. The immune workup demonstrated nearly absent levels of CH50, compatible with a complement pathway defect. Diagnosis delay ranged between 0 and 30 years. CONCLUSION: Awareness of risk factors for primary complement deficiencies, even at the first infectious episode, should facilitate prompt immune and genetic workup, commencing diagnosis and proper treatment for the patient and family. WHAT IS KNOWN: • Deficiencies in the classical terminal complement components increase susceptibility to invasive meningococcal infections. • Recurrent meningococcal infections mandate a diagnostic workup of the complement system. WHAT IS NEW: • Genetic workup can be utilized for prompt diagnosis of complement deficiencies. • High rates of consanguinity, even in the presence of a single meningococcal infection, should promote immune and genetic workups.