Chinese patients with late-onset Pompe disease develop symptoms and are diagnosed at least 10 years earlier than patients from other areas of the world, a Pompe disease registry shows.
The study, “Characteristics of Pompe disease in China: a report from the Pompe registry” was published in the journal Orphanet Journal of Rare Diseases.
Because of the rarity of Pompe disease, the Pompe Disease Registry (NCT00231400) was launched in 2004 to include the largest collection of data from patients around the world to help track patients’ clinical outcomes, irrespective of treatment status. China joined the registry in 2012, and the first Chinese patient was enrolled in 2013.
As of September 2016, 1,621 patients with Pompe disease from 34 countries were in the registry. Of these, 78 were from mainland China.
In this study, researchers reported the profile and outcomes of the 59 Chinese patients diagnosed with late-onset Pompe disease (LOPD) enrolled in the registry between January 2013 and September 2016.
There were 1,180 patients from the rest of the world included in the analysis. In this group, the majority (88.7%) had received treatment, compared to 86.4% of the 59 Chinese patients who never received enzyme replacement therapy (ERT), the only effective treatment available for patients with this rare disease.
The mean age for symptom onset among the Chinese patients with LOPD was earlier compared with patients from the rest of the world; 14.9 years versus 28.4 years, respectively. The same was seen for diagnosis, with Chinese patients receiving a diagnosis at age 22 compared to 35 for the other patients.
However, the time between onset of symptoms and diagnosis of Pompe disease was similar (around five years) in both groups. Five Chinese patients were only included in the registry after their death. Compared to patients from the rest of the world, Chinese patients died sooner — 21.8 versus 52.2 years.
Disease diagnosis of Chinese patients was most often achieved using DNA analysis (61.0%) and enzymatic assays (79.7%), although these tests varied between both groups. In the Chinese patients, the enzymatic assays used dry blood spot (46.8%) and “other blood-based assays,” while patients in the rest of the world were diagnosed via a wider range of assays, including muscle assays, dry blood spot and fibroblast assays.
The most common mutations in the Chinese cohort were c.2238G > C and c.2662G > T.
More than half the Chinese LOPD patients had respiratory and musculoskeletal symptoms, including shortness of breath after exercise (82%); need for respiratory support (52%); muscle weakness in lower extremities (87%), the trunk (67%), and upper extremities (57%); and difficulty walking (69%).
On top of these similar symptoms, a fraction of the patients from the rest of the world also lost the ability to walk (65%) and 50% used walking aid devices, not reported in Chinese patients.
Chinese LOPD patients had worse lung function compared to patients from the rest of the world, as shown by lower scores in several measures, such as forced vital capacity (FVC) — 37.2% vs. 63.5%.
Overall, “compared with patients from the rest of the world, Chinese patients with LOPD appeared to have younger age at symptom onset and diagnosis, lower lung function, and the majority had not received ERT,” the study concluded.
The Pompe Disease Registry (NCT00231400) is continuously recruiting.