Familial Mediterranean Fever MEFV Autosomal Recessive Pedigree

An 8-year-old boy of Sephardic Jewish descent presents with recurrent, self-limited episodes of fever (39–40°C), severe abdominal pain mimicking peritonitis, pleuritic chest pain, and monoarticular arthritis lasting 1–3 days, occurring every 4–6 weeks with complete asymptomatic intervals. His parents are unaffected distant cousins from an Armenian-Sephardic-Turkish-Arab background. Two of his five siblings have similar attacks. The pedigree pattern shown at **B** demonstrates which inheritance pattern and is most consistent with which diagnosis?