Whole exome sequencing identified a de novo variant in the IDS gene in a patient with mild form of the Mucopolysaccharidosis type II

Mucopolysaccharidosis (MSII) is described as a metabolic disorder resulting from an enzymatic failure causing from mutations in IDS gene, MPSII is divided into two forms; mild and severe. The first form does not affect intelligence and patients show no neurologic involvements, usually survive for the fourth decade of life. In patients with severe form, death mostly occurs due to neurologic involvement during the second decade of life. We reported a case, a 31-year-old patient, clinically suspicious to MPS II which was primarily diagnosed by the presence of the increased levels of dermatan and heparan sulfate in urine and I2S deficiency in plasma. Whole exome sequencing was utilized to detect the disease-causing variant in our patient. A de novo mutation (c.253G>A, (p.A85T) in exon 3 of the IDS gene was identified, which probably can describe the mild form of MPSII and clinical manifestations observed in the patient.