Abstract: Objective　To explore the value of peripheral blood smear examination in screening and diagnosis of infantile-onset Pompe disease (IOPD). Method　The results of peripheral blood smears in 29 children diagnosed with IOPD by enzymology and gene testing from 2013 to 2017 were retrospectively analyzed. Control values were obtained from 12 patients diagnosed with non-IOPD hypertrophic cardiomyopathy during the same period. Results　A large number of vacuolar lymphocytes were found in the blood smear of IOPD group, and the median percentage of vacuolar lymphocytes was 36% (19% - 67%). However, in the control group, almost no vacuolar lymphocytes were observed, and the median percentage of vacuolated lymphocytes was 0% (0% - 6.7%). A large number of periodic acid-schiff (PAS) positive lymphocytes were found in the blood smears of IOPD group, and the median percentage was 36% (19% - 66%). In control group, almost no PAS-positive lymphocytes were observed, and the median percentage of that was 0% (0% - 6.0%). The percentages of vacuolar lymphocyte and PAS positive lymphocytes between the two groups had significant difference (P < 0.01), and there was no overlap in the scatter plot. Conclusion　Peripheral blood smear examination is quick, simple and easy to perform. Observation and calculation of percentages of vacuolar and PAS positive lymphocyte are helpful for screening and early diagnosis of IOPD.

Key words: 　Pompe disease;　infant type;　diagnosis;　blood smear