Childhood absence epilepsy (CAE) is the subtype of Idiopathic generalized epilepsy (IGE). It accounts for 2-8% of patients with epilepsy. The frequency of CAE is more in girls than boys. The percentage of CAE in youngsters is 10-12%. In addition to CACNA1G, many other genes can be the possible cause of CAE. The pattern of inheritance of CAE is polygenic and complex. SNP might be a gain of function mutation in T- channel genes that results in increase T-type calcium channel activity. Ion channel genes and genes for GABA receptors are affected in epilepsy. By using various techniques of molecular genetics mutations have detected in genes of calcium channels (CACNA1H,CACNA1I, CACNA1A, CACNA1G and CACNB4), in genes of sodium channels like (SCN1B, SCN2A, SCN1A ) and genes for GABA receptor (GABRG2 and GABRD ). Gain of function mutation in CACNA1G gene and increased activity of α1G channels are the possible reason for abnormal SWD in absence epilepsy.
Aim of this study was to assess acknowledged and/or the novel mutations in CACNA1G gene obtained from local childhood epileptic patients.
Blood samples (n=20) were obtained from CAE patients. These samples were collected from children hospital Lahore. Organic method was used to extract DNA from these collected samples. Specific primers were designed for exon 13 and 17 and these exonic regions were amplified using PCR.
After PCR, sequencing of PCR products was performed and then sequencing results were analyzed using chromas lite software.
It has been observed that CACNA1G gene has two mutations in exon 17. It was noticed that protein sequence was altered and the positions of mutations were 38594bp and at 38635bp 38594bp and at 38635 bp. So SNP was detected and there was a gain of function mutation α1G channel activity. In conclusion, these mutations are responsible for absence seizures in CAE patients.
So, it can be concluded that to find out how individuals get affected by these mutations and what factors are involved in causing such mutation, a large scale study should be conducted.In addition, other genes involved in causing epilepsy should also be investigated in local Pakistani Punjab population. As a result of such studies, various diagnostic procedures, strategies for counseling and gene therapies can develop.