Refining the clinical phenotype of Okur-Chung neurodevelopmental syndrome.

We describe an 8-year-old Japanese boy with a recurrent missense mutation in , c.593A>G, that is causative of Okur-Chung neurodevelopmental syndrome. He exhibited distinctive facial features, severe growth retardation with relative macrocephaly, and friendly, hyperactive behavior. His dysmorphic features might suggest a congenital histone modification defect syndrome, such as Kleefstra, Coffin-Siris, or Rubinstein-Taybi syndromes, which are indicative of functional interactions between the casein kinase II, alpha 1 gene and histone modification factors.