| Disease ID | Source | Name | Description |
| 618744 | OMIM | Developmental and epileptic encephalopathy 83 (DEE83) | A form of epileptic encephalopathy, a heterogeneous group of severe early-onset epilepsies characterized by refractory seizures, neurodevelopmental impairment, and poor prognosis. Development is normal prior to seizure onset, after which cognitive and motor delays become apparent. DEE83 is an autosomal recessive form characterized by onset of frequent, intractable seizures in the first days to months of life. Affected individuals have profound developmental delay with no motor or language skill acquisition, and poor or absent visual tracking. Many patients die in the first years of life. The disease is caused by variants affecting the gene represented in this entry. A recurrent, pathogenic variant affecting the translation initiation codon of isoform 2 has been found in multiple DEE83 families. The variant results in the absence of isoform 2 and leads to reduced levels of functional UGP2 enzyme in neural stem cells. The absence of isoform 2 is compensated by an increased abundance of a functional isoform 1, carrying variant p.Met12Val, which may explain the survival of the patients. A complete absence of functional UGP2 in all cells would be embryonic lethal. |