Epilepsy

Genetic Testing for Epilepsy A Guide for Clinicians

KNOWING WHAT TO LOOK FOR

KNOWING WHERE TO LOOK

AND KNOWING WHAT IT MEANS

Figure 1.

Introduction Epilepsy is a common neurological disorder that affects at least 0.8% of the population. It is defined by the occurrence of at least two unprovoked seizures occurring more than 24 hours apart. Seizures are the manifestation of abnormal hypersynchronous discharges of cortical neurons lasting for several seconds, minutes, or longer. The clinical presentation of seizures depends upon both the location of the epileptic discharges in the cortex and the extent and pattern of propagation of the electrical discharges in the brain. In many cases, seizures result in convulsions and loss of consciousness. Seizures may also manifest in other ways that affect personality, mood, memory, sensation, and/or movement. Blank stares, lip smacking, intermittent eye movements, and jerking movements of the extremities are all examples of possible manifestations of seizures. In some cases these may not be recognized as a seizure by patients, their family members, or even health care professionals. Seizures can be classified into various categories (Figure 1). PLEASE REDRAW to make it look similarly to the one in the guide.

FIGURE 1: Types of seizures.

Generalized Tonic-Clonic 12-24%

Complex Partial 8-31% Absence 5-22% Simple Partial 2-12%

Infantile Spasms 1-9% Myoclonic 1-11%

Other Partial 7-29%

Other Generalized 6 months of age, ataxia, tremulousness, ‘‘happy’’ appearance, microcephaly, seizures

AD

CNTNAP2I,C,A SLC9A6I,C,A NRXN1I,C,A TCF4I,C,A UBE3AI,C,A

Autosomal dominant nocturnal frontal lobe epilepsy

Seizures arising from sleep, prominent motor manifestations

AD

CHRNA2C,A CHRNA4C,A CHRNB2C,A

Autosomal dominant partial epilepsy with auditory features

Ictal auditory symptoms and receptive aphasia, ± secondary generalization, benign course

AD

LGI1C,A

Baltic myoclonus (Unverricht-Lundbord disease)

Individuals in late childhood or adolescence with photosensitive myoclonus, seizures, ataxia

AR

CSTBC,A,P

Benign familial neonatal-infantile seizures (BFNIS)

Seizures from 2 days of age to 6 months, normal development

AD

SCN2A,I,C

Benign familial neonatal seizures (BFNS)

Neonatal seizures at approximately 3 days of age, resolution at