SNP Shot: Genomic Insights

Familial focal epilepsy with variable foci (FFEVF) is a rare, inherited type of epilepsy characterized by recurring seizures. These seizures, known as focal or partial seizures, originate in a specific area of the brain and typically do not cause a loss of consciousness. While FFEVF seizures can start at any age, from infancy to adulthood, they often begin in either the temporal or frontal lobe of the brain in over 70% of affected individuals. The seizure focus usually remains consistent within an individual over time. In some cases, the focal seizure activity can spread throughout the brain, leading to a secondarily generalized seizure, which involves loss of consciousness, muscle stiffening, and jerking movements.

A defining feature of FFEVF is the "variable foci," meaning that affected family members may experience seizures originating from different regions of the brain. The location where seizures begin can vary from person to person within the same family.

In some individuals with FFEVF, focal cortical dysplasia, a brain abnormality, is also present. Seizures in these cases are often difficult to manage with medication.

The majority of individuals with FFEVF have normal intelligence and show no signs of brain dysfunction between seizures. However, some individuals may develop psychiatric disorders (such as schizophrenia), behavioral issues, or intellectual disability. The connection between these additional features and FFEVF is currently unclear.

Inheritance:

FFEVF follows an autosomal dominant inheritance pattern. This means that only one copy of a mutated gene is needed in each cell to cause the disorder. Typically, an affected individual inherits the mutation from one parent. A specific gene, DEPDC5, is associated with FFEVF, but some individuals with a DEPDC5 gene mutation never develop the condition, a phenomenon known as reduced penetrance. Approximately 60% of individuals with a DEPDC5 gene mutation will develop FFEVF.