P.59 - Screening for late onset Pompe disease – Single center experience

Abstract

Late onset Pompe disease (LOPD, OMIM# 32300) is an autosomal recessive disorder caused by mutations of GAA gene encoding acid maltase. LOPD can present with a variety of neuromuscular phenotypes, from limb-girdle weakness to asymptomatic CK-emia. Several diagnostic approaches were proposed. Search for decreased GAA activity can be done either when other known causes of neuromuscular symptoms were excluded, or it can be the first screening step in a predefined population. Material and methods: a cohort of patients older than 5 y. with limb-girdle weakness or persistently elevated CK (more than 1.5× ULN). Enzyme activity from a dry blood spot (DBS) was estimated, followed by confirmatory testing if GAA levels were significantly reduced. 178 patients were tested (mean age 29.5 years, SD 19, range 5–78), 40% were women. Decreased GAA activity was detected in eight patients at first screening. It led to diagnosis of LOPD in 4 patients (2.2%), including two siblings of a boy originally tested for persistent CK-emia. DBS is useful for LOPD screening in patients with isolated CK-emia or limb-girdle weakness. LOPD ratio in our screened cohort is similar as in previously reported populations.