Pompe disease (PD) is a rare lysosomal disease caused by the deficient activity of
acid alpha-glucosidase (GAA) enzyme due to mutations in the GAA gene. The enzymatic
deficiency leads to the accumulation of glycogen within the lysosomes. Clinically,
the disease has been classically classified in infantile and childhood/adult forms.
Presently cc. close to 600 mutations distributed throughout the whole gene have been
reported. The c.-32-13T>G splice mutation that is very common in patients of Caucasian
origin affected by the childhood/adult form of the disease, with an allelic frequency
close to 70%. Enzyme replacement treatment (ERT) is available for the patients with
Pompe disease (Myozyme). In this paper, we are presenting the long term follow up
of 13 adult onset cases treated more than 5 years. The longest follow up was 15 years.
To evaluate the treatment efficacy, the 6 minutes walking test (6MWT) and the respiratory
functions were monitored annually. The analysis revealed that at the beginning of
ERT for 3-4 years the 6MWT had been generally increasing, then it declined, and after
10 years it was lower in 77% of the cases than it had been at the start of the treatment.
In 23% of the cases the 6MWT increased during the follow up time. Only one of the
patients become wheelchair dependent during the follow-up period. The respiratory
function showed similar results especially in supine position. A high degree of variability
was observed among patients in their responses to the treatment, which only partially
associated with the antibody titer against the therapeutic protein. The efficacy of
the ERT was associated with the type of the disease causing mutation, the baseline
status of the disease, the lifestyle and the diet of the patient. The long-term follow
up of the patients with innovative orphan drugs is necessary to really understand
the value of the treatment and the need of the patients.
