Plain Language Summary of A Study Looking at the Age at Diagnosis and Time to Start of Treatment in Individuals with Mucopolysaccharidosis Type I (Mps I)

Abstract

What is mucopolysaccharidosis type I? Mucopolysaccharidosis type I (also called MPS I) is a rare genetic condition that affects most parts of the body. MPS I develops when both parents pass a nonworking copy of the IDUA gene onto their child. This gene carries the information needed for cells to make the alpha-L-iduronidase enzyme, which breaks down complex sugar molecules called glycosaminoglycans (shortened to GAGs) inside cells. Individuals with MPS I do not produce a working (fully functional) version of the enzyme or might not produce any of it at all. Therefore, GAGs build up in their cells and bodies, which can lead to organ damage. Symptoms of MPS I include an enlarged liver and spleen, abnormal bone development, and specific facial characteristics. It is important to diagnose and treat MPS I as early in life as possible to prevent irreversible organ damage. There are two ways that individuals with MPS I can be treated, depending on how severe their disease is. Individuals with less severe, or ‘attenuated’, MPS I (Hurler-Scheie or Scheie syndrome) typically receive enzyme replacement therapy (shortened to ERT). This replaces the non-functional or missing enzyme. Those with severe MPS I (Hurler syndrome) typically undergo hematopoietic stem cell transplantation (also called HSCT), and ERT may also be used until the transplanted cells start making the enzyme. In HSCT, individuals receive stem cells from healthy donors so that their body can make the life-sustaining enzyme. This study looked at the age when individuals were diagnosed with attenuated or severe MPS I between 2003 and 2017, and the time taken for them to start treatment with ERT or HSCT following their diagnosis, using data from the MPS I Registry. What were the results? The age when individuals received a diagnosis of attenuated or severe MPS I did not change during the study period. The time taken from being diagnosed with attenuated MPS I to starting ERT decreased over time. The time taken from being diagnosed with severe MPS I to receiving HSCT was very short for the entire study period. What do the results of the study mean? These findings suggest that improvements in MPS I awareness and diagnosis are still needed. Clinical Trial Registration: NCT00144794 ( ClinicalTrials.gov )