Sanfilippo syndrome is transmitted as an autosomal recessive trait. It is possibly the most common of the mucopolysaccharide storage diseases. In Sanfilippo syndrome, onset is relatively late, rather than during the first year of life. As with most of the mucopolysaccharide storage diseases, affected individuals have coarse facial features, decreased mental development that progresses to severe mental retardation, stiff joints, gait disturbances, speech disturbances, and behavioral problems. Unlike Hurler syndrome, in people with Sanfilippo syndrome, the cornea is clear, the condition is not as unrelenting, and survival times are longer, often into the 20s or later.
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