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In this foundational webinar, Prof. Paul Harmatz from UCSF Benioff Children’s Hospital presents an engaging, case-based introduction to mucopolysaccharidoses (MPS), emphasizing the importance of clinical suspicion and pattern recognition in diagnosis. Designed to provide a practical approach for pediatricians, the session offers diagnostic clues, historical context, and insights from two compelling patient cases.
Prof. Harmatz begins by categorizing MPS within the larger group of lysosomal storage disorders (LSDs), highlighting their autosomal recessive inheritance patterns (with the exception of MPS II, which is X-linked) and their progressive nature. He explains that the clinical picture changes significantly with age and that pediatricians may initially see subtle signs that progress over time.
He describes the seven main types of MPS, focusing on the specific glycosaminoglycans (GAGs) that accumulate in each type—heparan sulfate, dermatan sulfate, keratan sulfate, or combinations thereof. These biochemical differences help guide laboratory testing and interpretation. For example, the presence of only heparan sulfate may point toward MPS III, while keratan sulfate is more suggestive of MPS IV (Morquio syndrome).
Dr. Harmatz stresses that certain clinical findings should raise immediate red flags: coarse facial features, hepatosplenomegaly, skeletal abnormalities (dysostosis multiplex), joint contractures without inflammation, hernias, and developmental delay. A gibbous deformity (prominent curvature of the lower spine) is particularly highlighted as an early and highly specific clue.
He presents two in-depth patient cases. The first child showed signs of skeletal dysplasia and a gibbous deformity at 18 months but was only referred to genetics years later. The second case involved a boy with hip and back pain who went undiagnosed for years due to borderline urinary GAG levels and mild clinical findings. Ultimately, advanced testing—including enzyme assays, electrophoresis, and tandem mass spectrometry—confirmed MPS VI and MPS IVA respectively.
Prof. Harmatz explains how current testing technologies, including dried blood spot enzyme assays and LC-MS/MS urine GAG analysis, have improved early detection and follow-up. He also emphasizes the promise of newborn screening programs, already implemented for MPS I and II in some U.S. states.
The webinar concludes by reinforcing the value of multidisciplinary collaboration and the pivotal role of pediatricians in identifying early signs. With timely diagnosis and access to therapies like enzyme replacement or stem cell transplantation, outcomes for MPS patients can be significantly improved.