Growth and Related Treatment Factors in Mucopolysaccharidoses Type I and II: A Systematic Review

Background: There is an association between treatment options and growth in patients with mucopolysaccharidoses (MPS). The appropriate management of MPS is an essential factor for the growth of the patients. Objectives: This study aims to review systematically the available data on the growth status and related treatment factors in patients with MPS type I and MPS type II. Methods: A systematic literature search was performed in PubMed, Scopus, and the Web of Science using related keywords by March 2023. In this systematic review, the primary outcome was determining the growth status (mainly height z-score) of patients with MPSI and MPSII from reviewed studies and its association with different treatment options. The author’s name, year of publication, country, type of MPS, growth status, treatment options, and any associations between growth status, disease, and treatment variables in the article were extracted. Results: From the initially retrieved 743 references, 100 were removed due to being duplicates, 31 articles were evaluated by reading the full text, and finally 20 were included in the systematic review. Based on the analyses, treatment options improved growth in the MPS patients. Certain variables regarding the treatment were key factors, such as the age of treatment initiation, combination therapy, and human growth hormone therapy. Some factors related to the characteristics of the patients, including genotype (type of mutation) and disease severity, are also key factors. Patients with MPSI and MPSII had normal growth and height during the first years of life, but after 2-5 years, their growth rate decreases progressively. Conclusions: The findings of this review indicated that growth impairment is common in patients with MPSI and MPSII. Treatment improved the growth development in these patients but not as much as expected. Some patients’ characteristics, such as disease severity and type of mutations, affect treatment efficacy and height gain. From treatment-related factors, the most important factor is the age of treatment initiation. Regarding other factors such as donor type, human growth hormone administration, and combination therapies, current findings are inconclusive, and more studies are needed