• Register
  • Login
  • Bookmark this page!
Skip Navigation LinksHome Page    >    Epilepsy - convulsions
Pregnancy links...
Health links...
Genetics links...
Medical links...
Other links...

Epilepsy - convulsions

This is a group of disorders in the electrical activity of the brain, manifesting in convulsions. A convulsive episode is the expression of sudden, uncontrolled electrical activity in a specific area in the brain.

Clinical types

There are different types of epilepsy, and the causes are many and diverse:

  1. An environmental, non-genetic cause. Focal damage to the brain as a result of surgery, trauma, or damage from infection or hypoxia can cause convulsions. The environmental causes are not genetic and usually occur during the perinatal period.

  2. Some types of epilepsy have a genetic cause. One type, which is mild, causes febrile (fever-induced) convulsions - these are common, transient, do not require permanent treatment, and leave no damage. There are also more severe hereditary types that span the range of severity up to uncontrollable convulsions that gradually cause brain and developmental damage.

  3. There are a number of syndromes in which, apart from the epileptic focus, there are other disorders or other defects in the brain or in other tissues. These include MERRF (convulsions with muscular disease), convulsions with yellow teeth, convulsions due to benign tumors as seen in tuberous sclerosis, etc. It is important to differentiate these from the non-hereditary types, although this is not always possible.

Clinical signs

The signs vary according to the location and function of the region of the brain in which the irregular electrical activity occurs and the scope of the spread of this electrical activity to other regions of the brain.

In most cases, the cause is unknown. An environmental cause can be suspected if there is a clear-cut history of a disruption in the oxygen supply to the brain (hypoxia), such as an infection or cerebral hemorrhage.

A genetic cause should be considered if there is no known environmental cause, especially if there are other cases in the family.

The likelihood that a specific case will be genetic increases in the following situations:
  • Absence of an environmental cause that would indicate acquired damage.

  • Progression and worsening of the convulsions and/or neurological damage over time.

  • Presence of dystonic, involuntary movements.

  • Presence of more severe mental retardation than expected from the convulsions alone.

  • Absence of signs supporting environmental damage in a brain scan (CT or MRI).

  • Presence of signs indicating a genetic disease on examination of the child or in laboratory and/or scanning tests.

Cerebral hypertension secondary to hydrocephalus and chromosome disorders must be ruled out. It is especially important to rule out metabolic disorders such as leukodystrophies. All these conditions must be investigated by a geneticist and a physical examination carried out. It is important to look for spots on the skin, muscular weakness, changes in the teeth, and other signs, which can indicate a specific syndrome.

Inheritance pattern

In most cases, the cause is not hereditary. In the hereditary types, the risk of recurrence depends on the precise condition - see the table below. Inheritance can be multifactorial or autosomal dominant with incomplete penetrance. In the more severe types, inheritance may be autosomal recessive or mitochondrial.


A significant number of cases are transmitted by autosomal dominant inheritance with incomplete penetrance.

Associated features that can be demonstrated by ultrasound examination

In the classic types of epilepsy, usually there are no defects that can be identified by ultrasound examination during pregnancy. If a specific syndrome is diagnosed, such as a disorder of development of brain structure, tuberous sclerosis, etc., characteristic signs of these syndromes can then be looked for on ultrasound.

What is the risk of recurrence in a subsequent pregnancy?

This depends on which type of epilepsy the patient has. In cases where the cause of the brain damage is environmental, i.e. non-genetic, there is no increased risk of recurrence. In the hereditary cases, the risk of recurrence depends on the specific condition and is in accordance with the inheritance pattern of that condition and the relationship to the patient. In most cases when there is only one case in the family, the risk of recurrence is not high. When there are a number of affected individuals in the family, or there are signs that indicate that this is a genetic syndrome, there may be an increased risk of recurrence.

When there are 2 affected siblings, a hereditary metabolic disease should be suspected. The risk that further children will be affected is 25% in conditions transmitted by autosomal recessive inheritance, and 50% in conditions transmitted by autosomal dominant inheritance.

Molecular genetic information

The disease-causing genes and their locations for the different conditions are shown in the following table:
Type Heredity Location of gene Name of gene Function of gene Characteristic signs
Benign familial neonatal convulsions Autosomal dominant 20q


Potassium channels forming electrical voltage gradient Benign convulsions appearing at a few days of age. 10% have residual adult epilepsy. No mental retardation.
Nocturnal frontal lobe epilepsy Autosomal dominant 20q




Components A4 and B2 of the nicotinic acetylcholine receptor responsible for calcium permeability. Convulsions appearing in sleep. Starts in childhood and continues to adolescence. No mental retardation.
Generalized epilepsy with febrile seizure plus Autosomal dominant 19q13




Sodium channels forming electrical voltage gradient. GABA-A receptor. Febrile convulsions or general convulsions induced by fever. Sometimes partial convulsions.
Progressive myoclonic epilepsy of Unvezzicht Lunborg Autosomal recessive 6q24 EPM2a

Tyrosine phosphatase (tyrosine kinase antagonist) Myoclonic convulsions commencing in adolescence.
Familial idiopathic myoclonic epilepsy of infancy Autosomal recessive 16p13 Unknown Unknown Myoclonic convulsions from infancy. No mental retardation.
Severe myoclonic epilepsy of infancy Sporadic - autosomal dominant cases are due to a new mutation 2q24 SCN1A Sodium channel causing electrical voltage gradient. Myoclonic convulsions from infancy, progressing to mental retardation or walking instability.
Juvenile myoclonic epilepsy Multifactorial? Suspected gene on 6p and 15q. Unknown Unknown Convulsions from age 8-26. Myoclonic in the morning.
Idiopathic generalized epilepsy Multifactorial? Suspected gene on chrom-osome 18. Unknown Unknown Convulsions from adolescence, various types.

Diagnostic testing

An examination should be carried out by a geneticist in order to look for a specific genetic syndrome. A blood test should also be done to look for a chromosomal problems, and if necessary specific blood tests to look for metabolic diseases based on the results of the geneticist-s examination. If the clinical presentation indicates that there is a mutation in a specific gene, genetic testing can be done straight away if this is available. Investigation is also possible in the familial cases. It is then possible to examine the location of the gene causing the disease in the specific family by linkage analysis. See information sheet: Indirect testing for genetic markers in a family with one or more patients in the family - when there are a number of different genes that can each cause the disease - not all the genes having been located / identified / mapped - autosomal dominant disease

Carrier testing

This cannot usually be performed, unless there is a specific syndrome whose gene can be tested for. See above in the section on diagnostic testing.

Fetal testing

This cannot usually be performed, unless there is a specific syndrome whose gene can be tested for. See above in the section on diagnostic testing.

What Causes Epilepsy?

Haven't found what you're looking for? Search for it here:   
Comments (7)

Thursday, October 09, 2014 2:38 AM
(1) home-finance  says:


PUA is usually a term helpful to describe an application that is not inherently detrimental, but is often considered unsuitable for the majority of small business networks. home-finance

Thursday, October 09, 2014 2:40 AM
(2) travel  says:


Whether a keen traveler or maybe someone whose ambition is that overall flexibility, TravelWize by means of Gullivers Vacations has introduced the right discount method. travel

Thursday, October 09, 2014 2:41 AM
(3) international-to  says:


You can opt for the world expedition packages in line with your prices or this themes consisting of sightseeing organized tours, specialty organized tours and voyage tours. international-tours

Wednesday, January 07, 2015 7:16 AM
(4) Unneville  says:


We have so many knowledge and best content providing services and these are all helps to our education life and those all steps are providing good victoria assignment help website educational steps and other tips are all.

Monday, January 26, 2015 5:33 AM
(5) lafseo90  says:


Epileptic seizures are scenes that can change from concise and almost imperceptible to long stretches of overwhelming shaking. In epilepsy, seizures have a tendency to repeat, and have no prompt hidden reason while seizures that happen because of a particular reason are not esteemed to speak to epilepsy. it resume template

Friday, February 06, 2015 4:05 AM
(6) dfgsdf  says:


A convulsion is really a medical condition exactly where physique muscle groups commitment and also take it easy rapidly and also frequently, leading to a uncontrolled wiggling with the physique. Just because a convulsion is usually a sign of an epileptic seizure, the phrase convulsion may also be used as being a synonym regarding seizure. webryze seo

Thursday, February 26, 2015 5:19 AM
(7) job application  says:

job application form

I dream of becoming a doctor is all about blogs is sending me very interested. Thank you for your helpful blog, I enjoyed it.

Leave a Comment
Email (will not be published)
Website (optional)
Your Comment

Line and paragraph breaks are automatic. Some HTML allowed: <a href="" title="">, <b>, <i>, <strike>

Please type the characters you see in the picture:

All content Copyright © 2009-2011, Genetics of Pregnancy Encyclopedia Corporation. All rights reserved.