Familial and sporadic 15q13.3 microdeletions in idiopathic generalized epilepsy: precedent for disorders with complex inheritance.

Authors:
Leanne M Dibbens, Saul Mullen, Ingo Helbig, Heather C Mefford, Marta A Bayly, Susannah Bellows, Costin Leu, Holger Trucks, Tanja Obermeier, Michael Wittig, Andre Franke, Hande Caglayan, Zuhal Yapici, - -, Thomas Sander, Evan E Eichler, Ingrid E Scheffer, John C Mulley, Samuel F Berkovic
Year of publication:
2009
Volume:
18
Issue:
19
Issn:
0964-6906
Journal title abbreviated:
HUM MOL GENET
Journal title long:
Human molecular genetics
Impact factor:
5.985
Abstract:
Microdeletion at chromosomal position 15q13.3 has been described in intellectual disability, autism spectrum disorders, schizophrenia and recently in idiopathic generalized epilepsy (IGE). Using independent IGE cohorts, we first aimed to confirm the association of 15q13.3 deletions and IGE. We then set out to determine the relative occurrence of sporadic and familial cases and to examine the likelihood of having seizures for individuals with the microdeletion in familial cases. The 15q13.3 microdeletion was identified in 7 of 539 (1.3%) unrelated cases of IGE using quantitative PCR or SNP arrays and confirmed by array comparative genomic hybridization analysis using probes specific to the 15q13.3 region. The inheritance of this lesion was tracked using family studies. Of the seven microdeletions identified in probands, three were de novo, two were transmitted from an unaffected parent and in two cases the parents were unavailable. Non-penetrance of the microdeletion was identified in 4/7 pedigrees and three pedigrees included other family members with IGE who lacked the 15q13.3 deletion. The odds ratio is 68 (95% confidence interval 29-181), indicating a pathogenic lesion predisposing to epilepsy with complex inheritance and incomplete penetrance for the IGE component of the phenotype in multiplex families.