Clinical assessment of upper airway and its complications in Hunter syndrome

Background Hunter syndrome (HS) is an X-linked, recessive, lysosomal storage disease caused by a deficiency of the lysosomal enzyme, iduronate sulfatase (IDS). It is characterized by multisystem accumulations of glycosaminoglycans and upper airway obstruction is one of the major causes of death. While the current disease severity classifications for HS are mainly based on the degree of neurocognitive impairment, its association with the level of upper airway obstruction has not been assessed. Methods A retrospective chart review of HS patients who were followed at the Jikei University School of Medicine was performed. Association between the degree of airway obstruction and the currently used disease severity scores was evaluated. Results We identified eight HS patients and they were enrolled in the study. The Modified Mallampati classification (MMC) score, used to predict difficulties for oropharyngeal procedures, was significantly correlated with the HS severity. It was also correlated with the Apnea-Hypopnea Index (AHI). No significant correlation between IDS enzymatic activity and the severity of HS disease was identified. Conclusions Variable clinical expressivities exist in HS, but the risk of respiratory complications is likely to be associated with disease severity, assessed by the previously recognized neurocognitive function-based severity scoring systems. MMC can be a simple supplementary tool to evaluate disease severity as well as predict difficulties for oropharyngeal procedures and respiratory function complications in HS, such as sleep apnea.

Automated summary

Hunter syndrome is a lysosomal storage disease caused by a deficiency of the enzyme iduronate sulfatase. Upper airway obstruction is a major complication, and the severity of this obstruction is correlated with disease severity as assessed by neurocognitive function-based scoring systems. The Modified Mallampati classification can be a useful tool in evaluating disease severity and predicting respiratory complications in Hunter syndrome.