Chromosomal Micro-aberration in a Saudi Family with Juvenile Myoclonic Epilepsy

Background and objective: Epilepsy is etiologically and genetically complex neurological disorder affecting millions of people worldwide. Juvenile myoclonic epilepsy (JME) is the most common epilepsy syndrome that starts in the teen age group commonly between ages 12, 18, and lasts till adulthood. One out of fourteen people with epilepsy suffers with JME. Myoclonic seizures and muscle twitching or uncontrolled jerking are the most common type of seizures in the people suffering with JME.

Method: To observe the novel CNVs involved in JME, we investigated a Saudi family with nine siblings including one male and one female affected members. In this study we used high density whole genome Agilent sure print G3 Hmn CGH 2x 400K array-CGH chips. Our results showed CNVs including the amplifications and deletions in different chromosomal regions in the patients as compared to the normal members of the family. Amplifications were observed in the chromosome 22 cytoband 22q11.23 with LDL receptor related protein 5 like (LRP5L), Immunoglobulin Lambda-Like Polypeptide 3 (IGLL3) and crystallin beta B2 pseudogene (CRYBB2P) genes respectively whereas the deletions were observed in the chromosomal regions 4q22.2 with Glutamate receptor, ionotropic, delta 2 (GRID2) as potential gene cytoband 1p31.1 with potential Neuronal Growth Regulator 1 gene (NEGR1) gene in this region and NME/NM23 family member (NME7) gene cytoband 1q24. Moreover, the array CGH resulting in deletions and duplication were also validated by using primer for simple PCR or also by using quantitative real time PCR analysis. We found deletions and duplication in JME patients in our study for the first time in Saudi population.

Results & conclusion: The findings in this study suggest that the array-CGH may be considered as a first line of genetic testing for diagnosis of epilepsy unless strong evidence is presented for a monogenic syndrome. The use of high throughput technique in this study will help to identify novel mechanisms underlying epileptic disorder in order to lower the burden of epilepsy in Saudi Arabia.