Gene Testing for Epilepsy SCN1A gene related disorders
Up to 3% of the population may suffer from one of the many forms of epilepsy. It affects people of all ages, races and ethnic backgrounds and often develops in early childhood.
Breakthroughs in genetic research have now identified particular genes responsible for certain types of epilepsy for which the cause was previously unknown.
The SCN1A gene
The SCN1A gene codes for the alpha subunit of a neuronal voltage-gated sodium channel and is located on chromosome 2q containing 26 exons.. Early manifestations of the disease are tonic, clonic, and tonic-clonic seizures that occur within the first year of life. These seizures are often prolonged, generalized, and associated with fever. Later in life, patients with SMEI have afebrile seizures, including myoclonic, tonic-clonic, absence, and simple and complex partial seizures. Early psychomotor and speech development is normal, but developmental stagnation occurs by the second year.
Defects in SCN1A are the cause of familial febrile convulsions 3 (FEB3) also known as familial febrile seizures 3. Febrile convulsions affect 5-12% of infants and children up to 6 years of age.
Defects in SCN1A are also the cause of familial hemiplegic migraine 3 (FHM3). FHM3 is an autosomal dominant severe subtype of migraine with aura characterized by some degree of hemiparesis during attacks. The episodes are associated with variable features of nausea, vomiting, photophobia and phonophobia. Age at onset ranges from 6 to 15 years.
SCN1A gene mutation analysis
Genetic testing is now being used to identify changes in the gene known as SCN1A. SCN1A gene test assists in diagnosing Severe Myoclonic Epilepsy of Infancy (SMEI) or Dravet Syndrome and other syndromes within the Generalised Epilepsy with Febrile Seizures Plus (GEFS+) spectrum.
Mutations in SCN1A are the cause of generalized epilepsy with febrile seizures in children and afebrile seizures in adults plus type 2 (GEFS+2). Penetrance is incomplete and a large intrafamilial variability of the phenotype is observed. Missense mutations in this gene have been recently reported in families with severe myoclonic epilepsy of infancy (SMEI)
The SCN1A gene test assists in making an accurate, early and definitive diagnosis for individuals experiencing seizures and may provide patients and families with information on the potential severity of the epilepsy and the optimal management options available.
For details of ordering the SCN1A genetic testing please click here.
Download the Epilepsy Patient Brochure or download the Clinician Epilepsy brochure.
For details of a genetic service in your area, contact Genetic Technologies.