MED23-associated intellectual disability in a non-consanguineous family

Intellectual disability (ID) is a heterogeneous condition arising from a variety of environmental and genetic factors. Among these causes are defects in transcriptional regulators. Herein, we report on two brothers in a nonconsanguineous family with novel compound heterozygous, disease-segregating mutations (NM_015979.3: [3656A > G];[4006C > T], NP_057063.2: [H1219R];[R1336X]) in MED23. This gene encodes a subunit of the Mediator complex that modulates the expression of RNA polymerase II-dependent genes. These brothers, who had profound ID, spasticity, congenital heart disease, brain abnormalities, and atypical electroencephalography, represent the first case of MED23-associated ID in a non-consanguineous family. They also expand upon the clinical features previously reported for mutations in this gene.