PAS‐positive lymphocyte vacuoles can be used as diagnostic screening test for Pompe disease

Abstract

Screening of blood films for the presence of periodic acid-Schiff (PAS)-positive lymphocyte vacuoles is sometimes used to support the diagnosis of Pompe disease, but the actual diagnostic value is still unknown. We collected peripheral blood films from 65 untreated Pompe patients and 51 controls. Lymphocyte vacuolization was quantified using three methods: percentage vacuolated lymphocytes, percentage PAS-positive lymphocytes, and a PAS score depending on staining intensity. Diagnostic accuracy of the tests was assessed using receiver operating characteristic (ROC) curves. All three methods fully discerned classic infantile patients from controls. The mean values of patients with milder forms of Pompe disease were significantly higher than those of controls, but full separation was not obtained. The area under the ROC curve was 0.98 for the percentage vacuolated lymphocytes (optimal cutoff value 3; sensitivity 91%, specificity 96%) and 0.99 for the percentage PAS-positive lymphocytes and PAS score (optimal cutoff value 9; sensitivity 100%, specificity 98%). Our data indicate that PAS-stained blood films can be used as a reliable screening tool to support a diagnosis of Pompe disease. The percentage of PAS-positive lymphocytes is convenient for use in clinical practice but should always be interpreted in combination with other clinical and laboratory parameters.

Enhanced delivery of α-glucosidase for Pompe disease by ICAM-1-targeted nanocarriers: comparative performance of a strategy for three distinct lysosomal storage disorders

“…2,36 Glycogen accumulation was verified by staining fixed cells with periodic acid-Schiff (PAS). 37 Semi-quantitative measurement of glycogen was assessed using an Olympus IX81 microscope (Olympus, Inc., Center Valley, PA) with a 40X objective (UPlanApo, Olympus, Inc.). Bright field micrographs were captured under blue, green and red filters (1160A-OMF, 3540B-OMF, 4040B-OMF; Semrock, Inc., Rochester, NY) with an ORCA-ER camera (Hamamatsu Corporation, Bridgewater, NJ) and combined them with SlideBook ™ 4.2 (Intelligent Imaging Innovations, Inc., Denver, CO).…”

Vacuolated PAS‐positive lymphocytes as an hallmark of Pompe disease and other myopathies related to impaired autophagy

“…In our series of neuromuscular patients, we found more than four PAS-positive lymphocytes in three patients suffering from glycogenosis other than Pompe disease (two subjects with GSD IV and one with GSD X). Although it has been previously hypothesized that PASpositive staining of lymphocytes might be present in other metabolic diseases such as oligosaccharidosis or non-lysosomal glycogen storage diseases (Hagemans et al, 2010), to our knowledge, this is the first demonstration of the presence of PAS-positive vacuolated lymphocytes in glycogen storage disease other than GSDII. Among the other neuromuscular patients, only one patient with caveolin-3 myopathy displayed a number of PAS-positive granules greater than 4.…”

“…To our knowledge, the finding of PAS‐positive vacuoles in lymphocytes has been reported exclusively in Pompe disease patients (Anderson et al, , Lim et al, ), suggesting that their presence can be specific for Pompe disease. According to the literature, presence of vacuolated lymphocytes positive to PAS staining seem less frequent in milder forms compared to IOPD (Hagemans et al, ).…”

“…However, only lymphocytes from patients with Pompe disease stained positively with PAS reagent (Anderson, Smith, Malone, & Sebire, ). Recently, Hagemans et al () observed peripheral blood films collected from patients with Pompe disease and healthy controls. They found that quantification of PAS‐positive lymphocytes in peripheral blood films is a determinant, able to discern patients with Pompe disease from controls, whereas some overlap was found between values of milder forms of Pompe disease patients and controls (Hagemans et al, ).…”

“…However, even though DBS analysis seems to be a useful tool in the diagnosis of LOPD, it has some limitations such as the requirement to be carried out in specialized laboratories and, above all, to be unable to controls. They found that quantification of PAS-positive lymphocytes in peripheral blood films is a determinant, able to discern patients with Pompe disease from controls, whereas some overlap was found between values of milder forms of Pompe disease patients and controls (Hagemans et al, 2010). Thus far, this test has not been formally validated and it has been only used as a quick screening tool for the differential diagnosis of Pompe disease, prior to confirmation by enzymatic or genetic analysis, or as a secondary test to support the diagnosis (Hagemans et al, 2010;Kishnani et al, 2014).…”