A study published in JAMA Pediatrics supports the use of genetic testing, especially with DNA sequencing, as the first-line diagnostic method for children under three years of age experiencing epilepsy and seizures.
Challenges of seizure management
Epilepsy is a nervous system disorder characterized by unprovoked, repeated seizures. Although it can affect all age groups, it is common in young children. Management with medications can control seizures for nearly 80% of individuals with epilepsy. Since early-life epilepsies are often a consequence of numerous neuro-developmental disorders with genetic origins, treating children under the age of three is more difficult. Adding to the complexity is that the cause of seizures in children under the age of three with epilepsy is unknown.
Identifying the cause of seizures
The ability to quickly identify the precise cause of a child’s epilepsy helps doctors choose the most effective treatment to control seizures and promote healthy brain development. Currently, young children presenting with seizures typically undergo neuroimaging as part of their initial diagnostic workup. Genetic testing that examines a patient’s DNA for changes that cause disease, is now also an option. There are several types of genetic tests which can be performed:
- karyotyping to determine the number and appearance of the chromosomes,
- microarray to determine if a gene is being fully expressed (is fully functional),
- epileptic gene panels which sequence genes to test for alterations in known epilepsy-related genes,
- and whole genome sequencing which reads the entire DNA sequence.
The diagnostic testing results
Led by Dr. Anne Berg, a team of researchers from Chicago sought to determine the patterns of use and diagnostic effectiveness of these genetic tests for early-life epilepsies. Medical records for 775 children (408 males, 367 females, the median age at onset = 7.5 months) with early seizure onset were examined. The 725 children who passed the study criteria underwent neuroimaging (80% were epilepsy protocol magnetic resonance imaging). However, only 38% of these tests yielded a specific diagnosis or indicated a developmental or progressive brain disorder. Karyotyping confirmed genetic diagnoses in 44 children (such as trisomy or other chromosomal additions or deletions). Another 188 children had chromosomal microarray. Gene panels were done for 114 children and 43 received whole exome sequencing.
Dr. Berg and her colleagues found whole genome sequencing and epileptic gene panel testing provided a diagnosis 33% and 27% of the time. Microarray and karyotyping provided a diagnosis just 17% of the time. This study also showed that specific genetic factors were found to be the cause of seizures in 40% of the patients. Alternatively, genetic testing provided a diagnosis in 25% of the children whose cause would have otherwise remained unknown.
Genetic testing is not consistently diagnostic
This study, published in JAMA Pediatrics does have some limitations. This study was not population-based. In addition, all the data was pulled from medical records so testing was not systematic and results were not always available for review. Nonetheless, it indicates that not all genetic tests are equally effective. The authors argue that these results support routine genetic testing for the initial evaluation of seizures in young children. Beyond diagnosis, this genetic information may also help inform treatment by alerting doctors to whether a drug is likely to inhibit or provoke seizures for a child depending on the cause of their epilepsy.
Reference
- Berg AT, Coryell J, Saneto RP, et al. Early-life epilepsies and the emerging role of genetic testing. JAMA Pediatr. 2017;171(9):863-871. doi:10.1001/jamapediatrics.2017.1743
