Impact of Early Diagnosis and Timely Treatment on the Natural History of Type I Mucopolysaccharidosis - Scheie Phenotype

Background: Type I Mucopolysaccharidosis is an autosomal recessive genetic pathology of lysosomal origin due to variants in the α-L-iduronidase gene, responsible for a deficiency in the activity of the α-L-iduronidase enzyme (IDUA), which leads to intracellular accumulation of glycosaminoglycans, with subsequent cell damage and multi-organ dysfunction. The overall incidence is 0.54 to 1.84 cases per 100,000 newborns. There are three clinical forms with a variable degree of severity. Diagnostic confirmation is made by measuring the residual activity of the IDUA enzyme in leukocytes. Molecular analysis is performed by whole gene sequencing. Currently, there are approved treatments such as enzyme replacement therapy and/or hematopoietic stem cell transplantation.

Case Report: We present the case of an 8-year-old male patient and the product of third-degree consanguineous parents, with no family history of genetic diseases, clinical suspicion of metabolic/genetic disease from 9 months of age, and diagnostic confirmation by measuring IDUA enzymatic activity (null) in leukocytes and a homozygous variant of the IDUA gene. The treatment was stem cell transplantation and enzyme replacement therapy at the age of 2, presenting favourable clinical evolution and stabilisation of systemic compromise (no cardio-respiratory-vascular compromise, no spinal cord compression, no joint contractures, no audiological alterations, growth and age-appropriate development, no infections, stabilization of corneal opacity and glaucoma).

Conclusions: The importance of knowing this disease lies in the establishment of early diagnosis strategies, the timely start of specific treatment, impacting the natural history of the disease, quality of life and prognosis of patients, by approaching preventive, predictive, participatory and personalised medicine.