A heterozygous missense variant in the YWHAG gene causing developmental and epileptic encephalopathy 56 in a Chinese family

Background Developmental and epileptic encephalopathies (DEEs) are a heterogeneous group of severe disorders that are characterized by early-onset, refractory seizures and developmental slowing or regression. Genetic variations are significant causes of these changes. De novo variants in an increasing number of candidate genes have been found to be causal. The YWHAG gene is one such gene that has been reported to cause developmental and epileptic encephalopathy 56 (DEE56). Here, we report a heterozygous missense variant, c.170G > A (p.R57H), in the YWHAG gene that caused early-onset epilepsy and developmental delay in a Chinese family. Methods We described the clinical manifestations of the proband and his mother in detail. Then, we use trio-based whole-exome sequencing to search the etiology of this family. Results Both the proband and his mother exhibited early-onset seizures, intellectual disability, and developmental delay. While the proband attained seizure control with sodium valproate, his mother's seizures were not well controlled. Trio-based whole-exome sequencing revealed a heterozygous missense variant, c.170G > A (p.R57H), in the YWHAG gene, which was considered as the cause of early-onset epilepsy and developmental delay in this family. Conclusions Our report further confirmed that YWHAG haploinsufficiency results in developmental and epileptic encephalopathy 56.