Objective: To describe the natural history of Sanfilippo syndrome type A.
Methods: We performed a retrospective review of 46 children (21 boys, 25 girls) with Sanfilippo syndrome type A evaluated between January 2000 and April 2013. Assessments included neurodevelopmental evaluations, audiologic testing, and assessment of growth, adaptive behavior, cognitive behavior, motor function, and speech/language skills. Only the baseline evaluation was included for patients who received hematopoietic stem cell transplantation.
Results: Median age at diagnosis was 35 months, with a median delay between initial symptoms to diagnosis of 24 months. The most common initial symptoms were speech/language delay (48%), dysmorphology (22%), and hearing loss (20%). Early behavioral problems included perseverative chewing and difficulty with toilet training. All children developed sleep difficulties and behavioral changes (e.g., hyperactivity, aggression). More than 93% of the children experienced somatic symptoms such as hepatomegaly (67%), abnormal dentition (39%), enlarged tongue (37%), coarse facial features (76%), and protuberant abdomen (43%). Kaplan-Meier analysis showed a 60% probability of surviving past 17 years of age.
Conclusions: Sanfilippo type A is characterized by severe hearing loss and speech delay, followed by a rapid decline in cognitive skills by 3 years of age. Significant somatic disease occurs in more than half of patients. Behavioral difficulties presented between 2 and 4 years of age during a rapid period of cognitive decline. Gross motor abilities are maintained during this period, which results in an active child with impaired cognition. Sleep difficulties are concurrent with the period of cognitive degeneration. There is currently an unacceptable delay in diagnosis, highlighting the need to increase awareness of this disease among clinicians.