Immunohistochemical surrogate for ATRX mutation

Quoted highlights on IHC mutational surrogates from: Tanboon J, Williams EA, and Louis DN. The Diagnostic Use of Immunohistochemical Surrogates for Signature Molecular Genetic Alterations in Gliomas. J Neuropathol Exp Neurol Vol. 75, No. 1, January 2016, pp. 4–18:

- Loss of nuclear staining for ATRX protein by immunohistochemistry has been used as a surrogate marker for ATRX mutations.

- Consistent and strongly positive staining in the nuclei of nonneoplastic endothelial cells and neurons is commonly used as internal positive controls.

- Unfortunately, there are no standard criteria (in terms of number of cells) for what constitutes loss of ATRX staining in gliomas.

- Because ATRX mutations are uncommon in IDH-mutant tumors with 1p/19q codeletion, it is suggested that ATRX, along with TP53 mutations, can be used as markers of astrocytic lineage.

- In adults, ATRX mutations have been reported either by sequencing or immunohistochemistry in 45%–67% of diffuse astrocytomas, 57%–73% of anaplastic astrocytomas, and 33%–57% of secondary glioblastoma; ATRX mutations are uncommon in primary glioblastoma (4%–7%)

- In children, ATRX mutations have been reported in 22% of pediatric diffuse intrinsic pontine gliomas and 48% of nonbrainstem high-grade gliomas in children;when ATRX mutation occurs in children, patients tend to be over 11 years old.