The analysis on OMIM morbid genes responsible for mental retardation associated or not with epileptic encephalopathy highlighted the presence of two rare heterozygous variants, one in HERC2, associated with an autosomal recessive form of mental retardation (MIM 615516), and one in FRAS1, associated with autosomal recessive Fraser syndrome 1 (MIM 219000). The gene discussed is HERC2; the disease is Epileptic encephalopathy.