Temple-Baraitser syndrome with KCNH1 Asn510Thr: a new case report.

Temple-Baraitser syndrome (TMBTS; OMIM: 611816) is a rare developmental disorder characterized by severe mental retardation and anomalies of thumb and great toe with absence/hypoplasia of the nails. Here, we report an additional patient with TMBTS, review clinical and radiological features of previously reported cases and discuss mode of inheritance. The patient exhibited a pattern of anomalies: mild dysmorphic facial features with a wide open mouth, a thick vermilion border of the upper lip and downturned corners of the mouth; nails were absent on both great toes and thumb. Electroencephalogram showed a diffusely slow background. Whole genome sequencing identified one pathogenic missense mutation in KCNH1 (c. 1529 A > C; Asn510Thr) in this TMBTS patient. The mutation was also validated by Sanger sequencing.