The loss of chromosome 3p21, which harbors several tumor-suppressor genes, such as BLU, RASSF1A, and SEMA3B, are frequently observed in cancers including gliomas, and the 3p21.31 region is a female-specific risk locus in astrocytoma and GBM (28–31). The gene discussed is SEMA3B; the disease is astrocytoma (excluding glioblastoma).