Recurrent seizures called epilepsy can occur alone or as part of a syndrome with other medical problems. In autosomal dominant inherited epilepsies, only one non-working copy of the gene can cause a person to have seizures. These syndromes usually have reduced penetrance, meaning an individual may not show disease even though he carries the genetic change. Other forms are autosomal recessive, which means that two non-working genes are inherited---one from each unaffected carrier parent.
Benign Familial Infantile Seizures
The onset of benign familial infantile seizures, or BFIS, occurs shortly after birth or later in infancy. They are usually inherited from a parent who also had seizures in infancy. These seizures are commonly well controlled with medications and generally stop as the child ages. Most often, an infant with BFIS develops normally without adverse outcomes.
Familial Febrile Seizures
Febrile seizures are triggered when an individual has a fever or is ill. Onset is generally between 6 months to 6 years of age. There are several different familial forms of febrile seizures, and some families have occurrences of generalized seizures as well. Outcomes for these children is generally is good. Several different genes are associated with the formation of familial febrile seizures; however genetic testing is only available for some.
Juvenile Myoclonic Epilepsy
Nearly 3 to 12 percent of individuals with epilepsy have this form. Characterized by grand mal, myoclonic and other types of seizures, juvenile myoclonic epilepsy, or JME, usually beings in adolescence. According to the online journal Neurologic Clinics, only one gene, GABRA1, has been discovered, though changes in this gene account for only a small percentage of familial JME.
Metabolic Disorders
Metabolism is the body's way of obtaining energy from food. Enzymes control this process. Disruption of metabolism causes disease that is often severe and life-threatening. Effective treatments have been discovered for many of these syndromes. They are usually inherited from parents who are unaffected carriers. A common feature of many metabolic disorders is epilepsy. Many of these syndromes are detected by newborn screening, allowing treatment to occur before devastating symptoms present.
Single-gene Disorders
Some chromosomal syndromes and other genetic defects have epilepsy as a feature. In these syndromes, a child has other medical problems such as intellectual disability, growth problems, cardiac defects and other malformations. These syndromes can be inherited from an affected parent, inherited from two parents who are unaffected carriers, or occur sporadically. Some of these syndromes include: Wolf-Hirschhorn, Angelman syndrome, Tuberous Sclerosis, Rett syndrome, and others.
References
- Neurologic Clinics: Advances on the Genetics of Mendelian Idiopathic Epilepsies
- "Vademecum Metabolicum: Manual of Metabolic Paediatrics (2nd Edition)"; Johannes Zschocke, Georg F. Hoffman; 2004
- "Thompson & Thompson Genetics in Metabolism (7th Edition)"; Robert Nessbaum; 2007
