Genetic analysis of PHOX2B in sudden unexpected death in epilepsy cases.

Abstract

To determine the contribution of sequence variations in PHOX2B to sudden unexpected death in epilepsy (SUDEP).Patients who died of SUDEP were identified in 2 major Australian cohorts, the Epilepsy Genetics research program in Melbourne and postmortem cases at the Department of Forensic Medicine in Sydney. Coding exons of the PHOX2B gene were sequenced and a fluorescent sizing assay was used to measure the PHOX2B polyalanine repeat sequence.Sequencing of 68 cases of SUDEP identified a 15-nucleotide deletion in the PHOX2B polyalanine repeat region in one case, a 16-year-old adolescent with focal dyscognitive seizures from age 5 years. This deletion was verified using a fluorescent sizing assay. Two synonymous variants were identified in 4 cases, but no PHOX2B polyalanine repeat expansion alleles or point mutations were found.The absence of PHOX2B polyalanine repeat expansion alleles or point mutations in 68 Australian cases of SUDEP, with one deletion of uncertain significance, shows that PHOX2B mutations are not a common risk factor for SUDEP.