Is Mucopolysaccharidosis a Cause of Sleep and Speech Disorders? Report of Four Cases?

Mucopolysaccharidosis type III (MPS 3) is an autosomal recessive disorder caused by a deficiency of one of the four enzymes involved in the lysosomal degradation of heparan sulfate (HS). It is often unrecognized or misdiagnosed in children as an idiopathic developmental/speech delay, attention deficit/hyperactivity disorder (ADHD), and/or autism spectrum disorder. It is characterized by progressive mental deterioration and behavioral problems with dysmorpilic facial features and mild somatic signs. We report on children with ADHD who were repeatedly admitted to the pediatric psychiatry department for sleep disturbances, hyperactivity, and speech delay; and to the emergency department with accidental corrosive substance ingestion. Children with mental retardation, coarse face, and hypertrichosis were referred to the pediatric gastroenterology department for preliminary diagnosis of MPS. Lysosomal enzyme activity examinations in leukocytes revealed increased levels of total glycosaminoglycans, heparin, and HS, and decreased HS sulphamidase activity, leading to the diagnosis of MPS III.