Clinical and neuroradiological follow-up in mucopolysaccharidosis type III (Sanfilippo syndrome).

Mucopolysaccharidosis type III (Sanfilippo syndrome) is an autosomal recessive disorder characterised by progressive nervous system involvement with mental retardation, behavioural problems and seizures. Three patients, of 20 months to 12 years of age, were followed up for 3 years both clinically and by using brain magnetic resonance imaging (MRI). Our results suggest that in MPS III patients MRI findings, including atrophy and abnormal or delayed myelination, may precede the onset of overt neurological symptoms. The increasing neurological morbidity is accompanied by different degrees of progressive atrophic changes, mainly affecting the cerebral cortex and the corpus callosum. However, it appears that, across subjects, the rate of MRI changes is unrelated to the severity of the clinical phenotype. On this basis it could be argued that in MPS III the worsening of the neurological symptoms might not necessarily reflect only the progressive cerebral abnormalities detectable by MRI.