Abstracts

Rationale: Established and recent literature implicates specific chromosomal aberrations as a cause for the channelopathies leading to Childhood absence epilepsy. Susceptibility to the development of childhood absence epilepsy may be conferred by variation in several genes including: JRK (8q24), GABRG2 gene (5q31.1), GABRA1 (5q34); GABRB3 (15q11-q12), SCN1B (19q13.1) and CACNA1H (16p13). The main purpose of this retrospective study is to characterize the clinical use of microarray chromosomal analysis, in a cohort of patients with childhood absence epilepsy.Methods: Chart review of a cohort of patients with childhood absence Epilepsy for the past 5 years (January 2008 to January 2013). Cases were classified as: A- refractory childhood absence (failed Valproate, ethosuximide, lamotrigine individually or in combination), B- With suspected comorbidity (different from ADHD, accompanied by delay or dimorphisms) or C- Presenting at early onset, early onset childhood absence epilepsy (ECAE, before age 3 years).Results: 64 cases were reviewed. A- 6 cases were refractory, B- 4 cases presented with mild nonspecific facial dimorphisms such as low set ears, broad forehead, or long filtrum and C- 5 cases of ECAE. Only in 5 cases was microarray chromosomal analysis requested: 3 children with developmental delay and non-specific dimorphism and 2 in children with behavioral and learning difficulties. In 3 cases microarray was positive: 1- 22q large deletion in a female with mild dimorphisms and delay, diagnosed by genetics as NOT velocardiofacial syndrome. 2- Micro deletion on chromosome 19 in a female with microcephaly and global delay. 3- 2p16.3 in a male with ECAE, and predominantly severe language delay. Normal microarray was reported in 2 patients with learning disabilities. There were no cases of glucose transporter defect type 1. This test was requested in only 2 of the 5 cases with ECAE, of which all responded well to 1 anticonvulsant.Conclusions: In this cohort of patients with childhood absence epilepsy, the use of microarray was low, considering novel indications include developmental delay of unknown etiology and autism. Chromosomal abnormalities were found by microarray analysis in more than half of the patients presenting with non-specific dimorphisms and learning, cognitive or behavioral comorbidities. Therefore, the routine use of microarray testing may be considered to be indicated in all such cases of childhood absence epilepsy. Further genetic analysis of those chromosomal deletions found is necessary in at least 1 case (2p16.3) since susceptibility to the development of childhood absence epilepsy was not found reported in the literature.