There is a hidden population of patients with late-onset Pompe disease (LOPD) in internal medicine departments, according to a study conducted in Spain. These patients may benefit from early diagnosis and early treatment initiation, according to the authors.

The researchers set out to determine the prevalence of LOPD in patients who have not previously been tested or diagnosed despite presenting possible signs or symptoms of the disease. The investigators analyzed 322 patients seen at internal medicine departments in Spain and who had a clinical suspicion of LOPD. 

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The study was published in the Orphanet Journal of Rare Diseases.

Disease diagnosis was initially established based on the result of dried blood spot analyses. In case of decreased acid alpha-glucosidase (GAA) enzyme activity on dried blood spots, enzyme activity in lymphocytes, fibroblasts, or muscle was analyzed, and genetic testing was performed.

The researchers confirmed a diagnosis of LOPD in 2 of the 322 patients that they analyzed. Reasons for suspecting such a diagnosis were polymyositis or any type of myopathy of unknown etiology in 1 patient and asymptomatic or paucisymptomatic hyperCKemia in the other. 

Two years had past from the time of symptom onset in the first patient while the second patient was diagnosed within the same year of his symptoms first appearing. 

Neither patient had symptoms of muscle weakness. 

The researchers reported that 19.7% of the 322 patients that they analyzed had alternative diagnoses.

“Further national studies, involving larger cohorts of patients and centers, are required to corroborate our results of LOPD prevalence in Internal Medicine departments,” the researchers concluded. 

LOPD commonly presents at a later age than infancy, unlike infantile-onset Pompe disease (IOPD). It also excludes severe cardiomyopathy, which is common in IOPD. LOPD is caused by the partial deficiency of the GAA enzyme.

Reference

López-Rodríguez M, Torralba-Cabeza MA, de Pedro IP, et al. Screening for late-onset Pompe disease in internal medicine departments in Spain. Orphanet J Rare Dis. Published online August 31, 2023. doi:10.1186/s13023-023-02887-z  

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