Researchers at Adelaide's Women's and Children's Hospital and the University of Adelaide, Australia, have found that a mutated gene is responsible for causing epilepsy and intellectual disability in women.
This breakthrough discovery has also shown that despite men carrying the 'bad' gene, it is only the women who get affected.
Led by Dr Leanne Dibbens and Associate Professor Jozef Gecz from the Department of Genetic Medicine, Women's and Children's Hospital, and the Discipline of Paediatrics at the University of Adelaide, the study has, for the first time, found a link between a large family of genes known as protocadherins with a condition known as "epilepsy and mental retardation limited to females" (EFMR).
Though uncommon, the disorder is mainly hereditary and affects successive generations of women.
The study examined seven families in Australia, the United States, Israel and Ireland and found 23 women to be affected by the disorder across five generations.
And the new discovery will help these families through genetic counselling, including screening for the genetic mutation at pregnancy.
"This is the first time this type of gene has been found to be involved in epilepsy. One of the most important discoveries we've made is that women in families affected by EFMR carry both a 'good' gene and a 'bad' (mutated) gene, while the men carry only the bad gene. For some reason, the men remain unaffected by the condition. We suspect this may have something to do with the male Y chromosome, but more research will be needed to find out exactly how or why," Nature quoted Dibbens, as saying.
He also added that the gene in question is vital for cell-to-cell communication in the brain, and may also help in understanding other related conditions like autism and obsessive disorders.
"With 100 related proteins involved in this gene family, this study could lead to many new areas of research, with the need to understand the role and function of each protein," she said.
Though it was more than 10 years ago that the disorder EFMR was first described, its cause is still unknown. It is a unique disorder among the epilepsies and mental retardations as it affects only females rather males, which is quite usual for X chromosome associated disorders.
The researchers also got an access to high-tech technological support including the sequencing of 737 genes on the X chromosome, conducted by collaborators at the Wellcome Trust Sanger Institute in the UK.
The study is published in Nature Genetics.