Hunter Syndrome: The Phenotype of a Rare Storage Disease

Abstract

Hunter syndrome is a rare lysosomal storage disorder with systemic involvement that occurs over time. Affected patients have coarse facial features, growth retardation with short stature, and skeletal deformities called dysostosis multiplex; joint stiffness, progressive mental retardation, and organomegaly are some of the clinical signs. It ranges from mild to severe manifestations and the distinction between them is related to neurological involvement. Cardiac and respiratory failure is commonly the cause of early death (before adulthood) for severe forms, but those with attenuated forms who have normal cognitive development can survive until late adulthood. Treatment with enzyme replacement therapy is available and can improve the prognosis of this disease. The authors present a case of a 36-year-old male with Hunter syndrome to show not only the clinical features typical of this multisystemic disease that should alert to a prompt investigation but also to remind that treatment must start as early as possible to reach the best outcome. Management of this disease is typically challenging and requires a multidisciplinary approach.

Keywords: dysostosis multiplex; hunter syndrome; inborn errors of metabolism; mucopolysaccharidosis; rare diseases.

Figure 1. This figure shows our patient who has mild Hunter syndrome with coarse facial features and a large head. The neck is short, the nose is broad with a flattened bridge, and the lips are thickened. Short stature is also observed.

Figure 2. Our patient has broad thickened hands with stubby digits.

Figure 3. Plain thoracic and abdominal X-ray of our patient showing dysostosis multiplex manifested as ribs broadened distally and narrowed at the takeoff from the vertebral bodies, resulting in the oar shape (red arrow).

Figure 4. Plain X-ray of our patient's arms with dysostosis multiplex manifested as distal radius and ulna with abnormal angulation and tilting of the distal epiphyses (red arrow).

Figure 5. Abdominal CT-scan showing massive hepatosplenomegaly seen in our patient before treatment.