Studies Stress Importance of Genetic Research

By Adam Modzelesky
EpilepsyUSA staff
Posted: December 9, 2004

Some of the world's foremost experts in genetics and epilepsy gathered at the 58th American Epilepsy Society Conference recently to present some fascinating new data.

Various laboratory studies and results were presented, and some of those studies were brought to life through real-life case descriptions.

Notable laboratory studies and results that were reported included a description of idiopathic generalized epilepsy and its frequency in twins, and a breakdown of the relationship between migraines and epilepsy.

One of the most memorable cases outlined was that of a girl who began having seizures in early adolescence and visual scintillations at age 15. Her case led researchers to question if a physiopathic relationship between epilepsy and migraines exists, especially since her family history included only migraines, not seizures.

None of the case studies mentioned in the conference program had patients who were successfully treated with medications, and they were all examples that stress the importance of studying genetics and epilepsy.

Brief History of Genetics

To lay the groundwork for the session entitled, "Genetics and Epilepsy Syndromes," Ruth Ottman, Ph.D., of Columbia University and a member of the Epilepsy Foundation's professional advisory board, outlined the history of genetics. She began by discussing the man who is arguably the founding father of modern genetics, Gregor Mendel.

In 1866, Mendel published the results of his groundbreaking work on garden peas. His study described how traits are inherited. Eventually Mendel's work, formally called Mendelian genetics, was proven to be too simplistic. In the early 1900s, Francis Galton and Karl Pearson said that a second set of laws was needed to be more consistent with blending genes. Blending genes refer to quantitative traits like the general population's average height or intelligence.

Frequency of Idiopathic Epilepsy in Twins

Samuel Berkovic, M.D., of the University of Melbourne in Australia, reported that idiopathic generalized epilepsy is primarily found in children and adolescents, and that twins "are a wonderful way to profile the condition idiopathic generalized epilepsy" because there is a great deal of concordance between the disorder and twins.

A wealth of evidence based on studies performed in Berkovic's lab show a certain trend - when one twin has a form of idiopathic generalized epilepsy, the twin tends to have the exact same. That cannot be said for a person's overall family, however. Whereas sub-syndromes of idiopathic generalized epilepsy are faithfully replicated in twins, sub-syndromes are mixed in families.

According to Berkovic, there is a 6 percent risk of the other twin inheriting idiopathic generalized epilepsy if the former suffers from it. In addition, there is a 10 percent risk of the other twin inheriting any type of seizure condition if the former has idiopathic generalized epilepsy.

Relationship Between Migraines and Epilepsy

The overriding theme in the presentation given by Ottman was that there is still not much known about epilepsy syndromes, hence the reason why it is so important to know about genotypes and phenotypes.

According to Ottman, a relationship between epilepsy and migraines could be based on one of two things: two separate genes or one shared gene. She said that there are three ways to determine this: Twin studies, familial aggregation or family concordance.

These last two methods of determining a connection seemed to fit in the case study presented by Edward Bromfield, M.D., professor of Neurology at Brigham and Women's Hospital, Harvard Medical School. Broomfield's patient, a girl who suffered from visual scintillations, occasional blindness and seizures at age 15, went through a host medications that were unsuccessful at treating her seizures. There was no history of seizures in her family, but there was a history of migraines. At least three generations on the maternal side suffered from visual auras. This fact led Broomfield to question if there is a physiopathic relationship between epilepsy and migraines, and why don't other family members have epilepsy?

Unfortunately, as Ottman points out, there is not yet enough known to definitively answer Broomfield's question. All researchers can do is suggest what might be causing these symptoms. Broomfield's case is just another example that proves further research is necessary.