Patients with SGS showed decreased p75NTR expression in all hippocampal formation subfields when compared to those with complex partial seizures (CPS), and the difference was statistically significant in the granular layer (SGS: 3030.8 ± 1232.7 × 102 μm2 versus CPS: 4200.1 ± 1271.1 × 102 μm2, t (38) = 2.51, p = 0.02), CA4 (SGS: 2073.3 ± 693.0 × 102 μm2 versus CPS: 2723.7 ± 664.9 × 102 μm2, t (35) = 2.25, p = 0.03), and CA2 (SGS: 3611.0 ± 833.5 × 102 μm2 versus CPS: 4631.6 ± 725.9 × 102 μm2, t (32) = 2.82, p = 0.01). The gene discussed is CA2; the disease is Focal impaired awareness seizure.