Chromosome 7 gain / 10 loss (+7/−10)

What it is

Combined chromosome 7 gain and 10 loss (written "+7/−10") is a chromosomal change in which tumor cells gain an extra copy of chromosome 7 and lose a copy of chromosome 10. This pattern is common in glioblastoma and is one of the molecular markers that can define it.

Understanding Chromosome 7 gain / 10 loss (+7/−10)

Chromosomes carry many genes, so gaining or losing whole chromosomes alters the balance of numerous genes at once. Gaining chromosome 7 (which carries growth-promoting genes, including EGFR) and losing chromosome 10 (which carries tumor-suppressing genes) together push cells toward aggressive growth. This combined pattern is characteristic of glioblastoma, and in the 2021 classification, an IDH-wildtype diffuse astrocytic glioma with +7/−10 (or a TERT promoter mutation, or EGFR amplification) is classified as glioblastoma even without the most aggressive appearance. Detecting +7/−10 requires molecular testing of the tumor. Understanding +7/−10 clarifies a chromosomal pattern common in glioblastoma and one of the markers that can define it.

Why it matters

Understanding +7/−10 helps patients and families see one of the molecular markers used in diagnosis — a chromosomal pattern that drives aggressive growth and can define glioblastoma even before the most aggressive appearance develops.