Global collaborations can help answer fundamental questions that are resistant even to national endeavours. Drs Mark McCormack and Christopher Whelan (MCT) and Professors Kieran Murphy (Psychiatry) and John Waddington (Emeritus, MCT) have participated in an important international study, the results of which have just been published in Science [2018 Jun 22;360(6395)] under the auspices of the Brainstorm Consortium. This landmark study, ‘Analysis of shared heritability in common disorders of the brain‘, analyses genetic data assembled globally from 265,218 patients having one of 25 neuropsychiatric disorders and 784,643 control participants, together with 1,191,588 individuals having 17 other, potentially relevant characteristics. Psychiatric disorders share an unexpected degree of common genetic risk: for example, genes associated with risk for schizophrenia are also associated, to varying extents, with significant risk for bipolar disorder, major depressive disorder, autism spectrum disorder, attention deficit/hyperactivity disorder, obsessive-compulsive disorder and anorexia nervosa; in contrast, neurological disorders such as epilepsy, stroke, Parkinson’s disease, migraine and multiple sclerosis appear more genetically distinct from one another. This highlights the importance of common genetic variation as a risk factor across psychiatric disorders.
John L. Waddington PhD, DSc, FBPhS, MRIA
MCT Research Talks – 20th February 2017
Sinead Heavin reports
Epilepsy is a common neurological disorder that affects ~40,000 people in Ireland. There are many different types of seizures which are caused by uncontrolled electrical impulses in the brain. Anti-epileptic drugs control seizures for ~50% of people with epilepsy but up to ~30% of patients remain uncontrolled despite treatment with multiple drugs. Epilepsy is caused by a number of factors include stroke, trauma and infections. However, more recently we have learned that epilepsy can be caused by genetic mutations. Some epilepsies are heritable while others arise de-novo. Many patients with an intellectual disability (ID) also have epilepsy. Many of these patients lack a specific diagnosis due to limited testing and available investigations. We sequenced a cohort of 99 adult patients with epilepsy and ID on a custom gene panel of ~150 genes. A likely pathogenic variant was identified in 20 patients in 19 different genes, including SCN1A, DCX and DEPDC5, well-known epilepsy genes. Furthermore, we identified copy number variants in two patients which are likely causative. Further work is needed to investigate the phenotype-genotype correlations identified in this study and any potential treatment options that may arise.
For most people with epilepsy, long term treatment with anti-epileptic drugs (AEDs) are necessary to prevent the seizure, and 40% do not respond to the first line of AED, leading to an often lifelong odyssey of trial and error towards effective treatment that is often not found. Epilepsy is primarily treated using AEDs, but these are associated with a considerable risk for adverse drug reactions (ADRs), some of which have been shown to have a genetic predisposition. For example, the genetic variant HLA-A*3101 is a common risk factor for rash and severe blistering skin reactions with the drug carbamazepine (Tegretol) in Europeans. However there are few other predictors of some more common ADRs.
The EpiPGX Consortium was established to identify genetic biomarkers of epilepsy treatment response from patient centres across Europe. The EpiPGX Consortium has generated genetic profiles on over 8000 patients with matching detailed drug response and medical histories. In order to investigate the links between genetic profiles and ADRs in epilepsy, Dr. Mark McCormack will travel to UMC Utrecht, the Netherlands for one year on a Marie-Skłodowska-Curie Fellowship from the European Commission.
The aim of this fellowship is to identify clinically useful genetic variants to predict adverse reactions to AEDs. This will help optimize personalized treatment, limit the trial and error approach of AED choice, and thus improve medication safety and quality of life in epilepsy.