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What is Epilepsy?
Epilepsy is one the common neurological disorders that causes seizures. The severity may range from a short lapse of attention, muscle jerks to relentless and extended convulsions. The seizures are caused by sudden, excessive electrical discharges in a group of brain cells i.e., neurons. Approximately, 50 million people all across the globe have epilepsy. However, 90 percent of the cases are found in developing regions. Epileptic patients are 2-3 times prone to premature death, as compared to the general population.
The most common type of epilepsy that is present in six out of ten people is called idiopathic epilepsy. It has been found that genetic factors have greater influence in this kind of disorder. However, there are other major types of epilepsy such as generalized epilepsy (childhood absence epilepsy, juvenile myoclonic epilepsy, etc), partial epilepsy (benign focal epilepsy of childhood), and symptomatic epilepsy, but idiopathic epilepsy is only caused by genetic factors.
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Deoxyribonucleic acid (DNA) is present in every human cell nucleus that makes up your genes. DNA is a double stranded structure that consists of four bases, which are called adenine (A), guanine (G), Cytosine (C), and Thymine (T). Gene is present on the DNA, which is a small section of the same and codes for a particular protein via translation process. During DNA replication, DNA forms a new and similar strand with the same ATGC configuration. However, sometimes, mismatch occurs that results into mutation. So, when a mutant DNA is transcribed and translated, the resulting protein formed does not work properly. Scientists have now confirmed that some of the genes that are involved in epilepsy have these mismatch errors.
Scientists have studied an individual with epilepsy in a family and correlated the inheritance of a specific DNA marker or a mutant gene. A variety of mutant genes have been identified that can be effectively assayed in small blood samples. They are doing genetic analysis to find mutant genes of interest. They first identify a family with epilepsy, and then collect DNA samples from family member with epilepsy, and family members without epilepsy. Next, genetic analysis is done on the blood sample to locate genes that might be involved in causing the epilepsy. Locations of genes of interest are identified, and finally the mutant genes can be found.
Some of the epileptic genes involved are KCNQ2, KCNQ3, SCN1B, SCN1A, and GABRG2.
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When a neurologist is confronted with a family where one or two persons are involved with epilepsy, it is desirable for the clinician to make the family aware of the disorder and explain about the same in detail. Well, as far as risk severity is concerned, it is dependent on the kind of epileptic syndrome. Moreover, the sex of the parent with epilepsy also determines the prevalence rate. Risk has been reported to be more when the mother is affected with the disorder. The risk of the siblings developing this disorder depends on various factors including the age at onset.
Clinical neurologists are using new techniques for the diagnosis and treatment of this disorder. They are considering genetic types to provide innovative therapies and the prevention of these disorders in future.
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(Web): Genetics of Epilepsy -- http://www.ias.ac.in/currsci/mar252002/671.pdf
(Web): Types of Epilepsy -- http://www.webmd.com/epilepsy/guide/types-epilepsy
(Web): Genetics of Epilepsy -- http://library.thinkquest.org/J001619/genetics.html
(Web): Molecular basis of an inherited epilepsy -- http://www.ionchannels.org/showabstract.php?pmid=12086636