Friday, February 19, 2016

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.




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