They are also commonly deficient for expression of ATRX protein, a repressor of ALT activity, and a component of promyelocytic leukemia nuclear bodies (PML NBs) that are required for intrinsic immunity to various viruses.
ATRX associates with the nuclear matrix, pericentromeric heterochromatin, and promyelocytic leukemia nuclear bodies (PML-NBs) in a speckled nuclear staining pattern.