Genetic analysis in a Chinese BAFME pedigree indicates the possibility of an unidentified locus

Benign adult familial myoclonic epilepsy (BAFME) is a rare adult-onset epilepsy syndrome with shivering-like tremor, myoclonus and seizure as core symptoms. BAFME has been mapped on 8q23.3-q24.1, 2p11.1-q12.2, 5p15.31-p15.1 and 3q26.32-3q28 in different families demonstrating genetic heterogeneity so far. We reported a large Chinese BAFME pedigree excluded linkage to chromosome 8q23.3-q24.1 and 2p11.1-q12.2 before. Recently, we further followed up this family and conduct electrophysiological examinations comprehensively. Linkage analysis was performed with 16 selected microsatellites encompassing the 4 above-mentioned locus. We re-investigated 46 individuals in this Chinese BAFME family and 21 individuals were diagnosed as BAFME. The possibility of this BAFME family linked with chromosome 2p11.1-q12.2, 3q26.32-3q28 or 5p15.31-p15.1 was excluded when assuming a dominant mode of inheritance. For 8q23.3-q24.1, the obtained maximum-LOD score and maximum-HLOD score were 1.717 and 1.717 at maker D8S1804. But no co-segregation of any haplotype with disease status was found by haplotype analysis. We inferred that the BAFME-causative gene in the Chinese pedigree may be located on an unidentified locus, indicating the genetic heterogeneity of BAFME.