Median serum BAFF levels in the NMO, MS, and control groups were 945.52 pg/ml (range, 278.14–1,942.81), 940.05 pg/ml (range, 245.60–1,722.99), and 962.40 pg/ml (range, 779.04–1,333.87). The gene discussed is TNFSF13B; the disease is neuromyelitis optica.