What Your Test Results Mean:

Carriers typically show no symptoms of northern epilepsy; however, carriers are at an increased risk of having a child with northern epilepsy. Risk for the current or future pregnancies is dependent on your partner’s carrier status. Carrier testing of your partner is recommended in addition to consultation with a genetic counselor.

Disease Explained:

Northern epilepsy is an inherited condition that causes recurrent seizures and progressive loss of intellectual function. Affected individuals seem normal in infancy and early childhood, but develop recurrent seizures between the ages of 5 and 10. These seizures are fairly frequent in childhood (1 to 2 per month) but decrease in frequency as the patient ages. Two to 5 years after affected individuals begin experiencing seizures, they start to lose some intellectual function, and as young adults also experience problems with coordination and balance. Individuals with northern epilepsy usually live into late adulthood, but depending on the progression of intellectual disability and movement impairment may not be able to live independently.

How the Genetics Works:

The clinical features of northern epilepsy can be explained by pathogenic variants in the CLN8 gene. In general, individuals have two copies of the CLN8 gene. Carriers of northern epilepsy have a single variant in one copy of the CLN8 gene while individuals with northern epilepsy have variants in both copies of their genes, one inherited from each parent. Risk for two carriers to have a child with the disorder is 25%.