Mucopolysaccharidosis Type II and the G374sp Mutation.

Mucopolysaccharidosis type II (MPS II), also known as Hunter syndrome, is a rare, X-linked disease caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase, which catalyses a step in the catabolism of glycosaminoglycans resulting in accumulation of heparan and dermatan sulfate in many organs and tissues. This accumulation favors the appearance of neurologic involvement, severe airway obstruction, skeletal deformities, and cardiomyopathy, especially mitral and aortic valve regurgitation. In severe cases, obstructive airway disease and cardiac failure due to valvular dysfunction are the most common causes of death within the second decade of life. However, in mild cases, intelligence remains normal, stature is almost normal and death usually occurs due to cardiac failure in the fourth decade of life. We report the presentation, diagnosis, management, and outcome of 2 siblings with MPS II and the G374sp mutation at the nucleotide c.1246 of the gene encoding for the iduronate-2-sulfatase.