[DNA sequencing of H3F3A mutations in H3.3 immunohistochemistry-negative giant cell tumors of bone]

Objective: To investigate the subtypes of H3F3A DNA mutation in H3.3 immunohistochemistry (IHC) negative giant cell tumors of bone (GCTB). Methods: IHC expression of G34W mutated protein was evaluated in 181 cases GCTB. In H3.3 IHC negative cases, Sanger DNA sequencing analysis was used to detect the subtypes H3F3A mutations. Results: Overall, 164 (90.61%) cases of GCTB showed nuclear expression of H3.3, and 17 cases were negative. These 17 H3.3 negative cases were subjected to Sanger DNA sequencing analysis; results showed that eight presented rare mutation subtypes occurring at glycine 34 to leucine (G34L, 3/181, 1.66%), glycine 34 to valine (G34V, 3/181, 1.66%) and glycine 34 to arginine (G34R, 2/181, 1.10%), and the other nine cases were wild type (glycine 34, 9/181, 4.97%). Sanger DNA sequencing analysis confirmed the absence of G34W mutation in the H3.3 negative cases. Combining IHC and DNA sequencing analysis increased the detection rate of H3F3A mutation in the GCTB to 95.03%. Conclusions: H3.3 IHC could detect H3F3A G34W mutation in GCTB, but not for other rare mutation and wild types loci.