SNP Shot: Genomic Insights

Autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) is a rare, inherited form of epilepsy that affects families. Individuals with this condition experience seizures, typically during nighttime sleep. While most seizures occur at night (nocturnal), some individuals may also experience them during the day.

ADNFLE seizures usually happen in clusters, with each seizure lasting from a few seconds to a few minutes. Seizure severity varies; some individuals may only wake up briefly, while others experience more pronounced episodes. These severe episodes can involve repetitive movements like arm flailing or leg bicycling. Individuals may also get out of bed and wander, resembling sleepwalking, and may vocalize through cries, moans, gasps, or grunts. Because of these behaviors, ADNFLE seizures are sometimes mistaken for nightmares, night terrors, or panic attacks.

Like other forms of epilepsy, ADNFLE can be preceded by an aura – a pattern of neurological symptoms. Common aura symptoms in ADNFLE include tingling, shivering, feelings of fear, dizziness (vertigo), and a sensation of falling or being pushed. Some individuals have also reported breathlessness, rapid breathing (hyperventilation), or choking sensations. The specific causes of ADNFLE seizures are not well understood. Stress and fatigue may act as triggers, but often there are no identifiable triggers.

The onset of ADNFLE seizures can range from infancy to mid-adulthood, although they most commonly begin in childhood. With age, these episodes tend to become less severe and less frequent. Medication is usually effective in controlling the seizures experienced by most affected individuals.

Generally, individuals with ADNFLE have normal intelligence and brain function between seizures. However, some may experience psychiatric disorders (like schizophrenia), behavioral issues, or intellectual disabilities. The relationship between these additional features and the epilepsy itself is currently unclear.

Inheritance:

ADNFLE follows an autosomal dominant inheritance pattern. This means that inheriting only one copy of a mutated gene is enough to increase the risk of developing epilepsy. Approximately 70 percent of individuals who inherit a mutation in the CHRNA2, CHRNA4, or CHRNB2 gene will develop seizures. In most instances, an affected individual has one parent with the condition and other affected relatives. Some cases are considered sporadic, meaning the affected individual has no family history of the disorder.