Mucopolysaccharidosis II (MPS II; Hunter syndrome; OMIM309900) is a rare, X-linked lysosomal storage disease caused by deficient activity of the enzyme iduronate-2-sulfatase (I2S), owing to deletion or pathological variants of the I2S gene (IDS) [1–3]. This evidence concerns the gene IDS and mucopolysaccharidosis type 2.