Prognostic factors for the late onset Pompe disease with enzyme replacement therapy: from our experience of 4 cases including an autopsy case.

We report 4 cases of late onset glycogen storage disease type II (GSD II) or Pompe disease (OMIM #232300), under enzyme replacement therapy (ERT) with recombinant human acid alpha glucosidase (rh-GAA, OMIM *606800). In these 4 cases, we focused on the case of a 28-years-old man, whose condition at the ERT starting was the worst and resulted in poor prognosis. The autopsy was done under his family's permission, and revealed severe accumulation of glycogen in his muscle, especially diaphragm or iliopsoas, and pulmonary veno-occlusive disease (PVOD) which resulted in severe pulmonary hypertension (PH). This is the first report of PVOD as the cause of PH in Pompe disease. We studied this case comparing to another 3 cases of late onset Pompe disease under the same course of ERT in our hospital, and the average data of the group of late onset Pompe disease with severe pulmonary insufficiency receiving ERT, supposed that low score of the body mass index (BMI) on the baseline, the presence of specific genotype (p.R600C), and signs of pulmonary dysfunction suggesting PH (tachypnea, ultrasound cardiography data) were factors that influenced the prognosis. For a better prognosis in the late onset Pompe disease, an early diagnosis for the early start of ERT before the onset of respiratory failure should be important, and the deliberate management and care should be needed even after the ERT start, especially for severe cases including pulmonary dysfunction.