Following intracerebral injection of the AAV encoding genes SGSH and SUMF1 in four children with Mucopolysaccharidosis Type IIIA disease, neurocognitive improvements were observed mainly in the youngest child aged 2 years and 8 months, suggesting that therapy in patients with MPS Type IIIA would be most efficacious for children <5 years of age with no noticeable brain atrophy [42]. Here, SUMF1 is linked to Brain atrophy.