Calretinin, a member of the calmodulin superfamily, is a 29-kilodalton, calcium-binding protein [44]; it is highly sensitive and specific for the detection of Meissner and Auerbach plexus ganglion cells (nuclear and cytoplasmic staining are considered positive markers) and is primarily used in the diagnosis of HD [18,45]. Here, CALB2 is linked to Huntington disease.