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Juvenile myoclonic epilepsy (JME) represents between 6 and 8 percent of all epilepsies. The syndrome consists of muscle jerks, often occurring in the morning upon wakening; there is no loss of consciousness. About 30 percent of patients with JME have family members with some form of epilepsy, not necessarily JME. Furthermore, JME is found in a family member of about 30 percent of epileptic patients. Research has suggested that a gene for JME might be located on chromosome 6, in close proximity to the genes of the major histocompatibility complex coding for HLA antigens that are important in immunology. A study has now been conducted using more sophisticated techniques of molecular biology to confirm this association. DNA fragments that are specific for the HLA-DQ region of the major histocompatibility complex were used to follow the putative inheritance of epilepsy among members of 21 families. This study confirmed that a gene important for the inheritance of epilepsy appears to be close to the HLA-DQ region on the short arm of chromosome 6 (6p). If only JME, absence seizures, or generalized tonic-clonic seizures are included in the analysis, the penetrance of the gene appears to be about 70 percent. This means that only about 70 percent of the people who inherit the gene actually develop one of these forms of epilepsy. However, some family members were found to have abnormalities on the electroencephalograph (EEG), without having actual symptoms of epilepsy. If these people are included in the analysis, then 90 percent of the people who inherit the gene have some sort of effect, even if they do not have actual symptoms of epilepsy. The random gene recombination events among the 21 families did not permit the researchers to determine if the gene in question is closer to the HLA-DQ genes than to other genes of the histocompatibility complex, such as HLA-A genes or HLA-B genes. Furthermore, the present study did not ascertain that the gene on chromosome 6 is the actual gene that causes the epilepsy. The gene studied may act only as a susceptibility gene, which renders the patient susceptible to some other gene or factors that cause the epileptic syndromes. (Consumer Summary produced by Reliance Medical Information, Inc.)

All women with epilepsy who are of childbearing age should be advised (preferably before conception) that the incidence of malformations in infants of mothers with epilepsy who are treated with antiepileptic drugs (AEDs) is two or three times that of infants of mothers without epilepsy. In addition, children of mothers with epilepsy, treated or untreated with AEDs, tend to have slightly more minor anomalies than do children of fathers with epilepsy or control subjects. We do not know which of the four major AEDs (phenytoin, carbamazepine, valproate, and phenobarbital) is the most teratogenic. If AED treatment cannot be avoided, the first-choice drug for the seizure type and epilepsy syndrome should be used as monotherapy at the lowest effective dose. Diet prior to conception and during organogenesis should contain adequate amounts of folate. Prenatal diagnosis of possible birth defects should be offered, and patients should be followed closely during pregnancy, labor, and puerperium. Despite the small but significant risks, more than 90% of women with epilepsy who receive AEDs during pregnancy will deliver normal children free of birth defects.