Gliomas are central nervous system neoplasms derived from glial cells and comprise astrocytomas, glioblastoma multiforme, oligodendrogliomas, ependymomas, and subependymomas. Glial cells can show various degrees of differentiation even within the same tumor (summary by Kyritsis et al., 2010).
Ependymomas are rare glial tumors of the brain and spinal cord (Yokota et al., 2003).
Subependymomas are unusual tumors believed to arise from the bipotential subependymal cell, which normally differentiates into either ependymal cells or astrocytes. They were characterized as a distinct entity by Scheinker (1945). They tend to be slow-growing, noninvasive, and located in the ventricular system, septum pellucidum, cerebral aqueduct, or proximal spinal cord (summary by Ryken et al., 1994).
Gliomas are known to occur in association with several other well-defined hereditary tumor syndromes such as mismatch repair cancer syndrome (see 276300), melanoma-astrocytoma syndrome (155755), neurofibromatosis-1 (NF1; 162200) and neurofibromatosis-2 (see SWNV, 101000), and tuberous sclerosis (TSC1; 191100). Familial clustering of gliomas may occur in the absence of these tumor syndromes, however.
Genetic Heterogeneity of Susceptibility to Glioma
Other glioma susceptibilities include GLM2 (613028), caused by variation in the PTEN gene (601728) on chromosome 10q23; GLM3 (613029), caused by variation in the BRCA2 gene (600185) on chromosome 13q13; GLM4 (607248), mapped to chromosome 15q23-q26.3; GLM5 (613030), mapped to chromosome 9p21; GLM6 (613031), mapped to chromosome 20q13; GLM7 (613032), mapped to chromosome 8q24; GLM8 (613033), mapped to chromosome 5p15; and GLM9, caused by variation in the POT1 gene (606478) on chromosome 7q31.
Somatic mutation, disruption, or copy number variation of the following genes or loci may also contribute to the formation of glioma: ERBB (EGFR; 131550), ERBB2 (164870), LGI1 (604619), GAS41 (602116), GLI (165220), DMBT1 (601969), IDH1 (147700), IDH2 (147650), BRAF (164757), PARK2 (602544), TP53 (191170), RB1 (614041), PIK3CA (171834), 10p15, 19q, and 17p13.3. [from
OMIM]