Febrile Convulsions, Familial, 1

Alternative Names

  • FEB1
  • Convulsions, Familial Febrile, 1
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WHO-ICD-10 version:2010

Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

General symptoms and signs

OMIM Number

121210

Mode of Inheritance

Autosomal dominant

Gene Map Locus

8q13-q21

Description

Febrile seizures or convulsions refer to generalized or focal convulsions, seen in children between the ages of 6 months and 5 years, caused by a sudden increase in body temperature. During an attack, which usually lasts for between one and five minutes, the child will typically lose consciousness, roll back his/her eyes, go stiff, and displays jerking movements of the body. Febrile convulsions can be of a simple or complex nature. The simple form involves the entire body, lasts for a lesser time, and does not recur for the next 24 hours, while the complex form focuses on a part of the body, lasts for a longer time, and recurs within a day. Febrile seizures are thought to occur in 2-5% of children between the ages of 6 months and 5 years. Up to 75% of these are cases of simple febrile seizures.

The most important factor while making a diagnosis of febrile convulsions is to rule out underlying meningitis and encephalitis. Simple seizures are easy to treat, and are usually not a cause for concern. In any case, the underlying cause for the high fever needs to be arrived at. Management involves controlling the fever, and preventing dehydration. Recurrence risk is generally low, and gets progressively lower as the child grows older. However, in patients with a family history of the condition, the recurrence risk may be as high as 50%. Prognosis is fairly good. Only about 1% of affected patients go on to develop epilepsy in later life.

As mentioned earlier, a family history of febrile convulsions in first degree relatives increases the recurrence risk of these seizures by about 50%. In addition, if either or both of the parents have a history of childhood febrile convulsions, then there is a 10-20% risk of having an affected child. Researchers are of the opinion that mutations in genes causing neuronal hyperexcitability could lead to febrile convulsions.

An autosomal dominant locus on chromosome 8q was the first genetic locus found to be associated with the condition (FEB1). Since then, several different loci have been discovered. These include the SCN1A (Sodium Channel, Neuronal Type I, Alpha Subunit), GPR98 (G Protein-Coupled Receptor 98), and GABRG2 (Gamma-Aminobutyric Acid Receptor, Gamma-2) genes, and several other loci on chromosomes 19p, 6q, 18p, 21q22, and 3p24.

Epidemiology in the Arab World

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Other Reports

Jordan

Abuekteish et al., (2000) conducted a prospective study of 203 children admitted with a first febrile seizure. Aseptic meningitis was diagnosed in nine children (4%). The mean age of the children was 19.9 months and the peak age incidence (88%) was between 6 months and 3 years. Complex seizures were seen in 16 cases (8%). There was a history of perinatal asphyxia in 16 patients (8%), positive family history of epilepsy in 3%, of first degree relatives and a history of febrile seizures in siblings in 13%.

In 2004, Daoud et al., investigated the risk of recurrence after a first unprovoked seizure in 265 Jordanian children and the risk factors associated with increased recurrence rate. The study included consecutive patients aged 3 months-14 years who presented with their first unprovoked seizures between January 1997 and 2000, with a follow up for 3 years for possible recurrence. Generalized seizures were reported in 75% and the remaining 25% had partial seizures. The duration of seizure was 1-4 minutes in 59%. Family history of epilepsy was positive in 31% and parental consanguinity in 32%. Ninety-eight (37%) of them experienced seizure recurrence. They also noted that the risk of recurrence was significantly higher in children with a partial seizure (55%) and among those with a positive family history of epilepsy (59%). Age at first seizure, sex, duration of seizure and consanguinity were not significantly related to the risk of recurrence.

Kuwait

El-Radhi and Banajeh (1989) reported 173 children (91 males and 82 females) with febrile convulsion during the period between January 1980 and February 1986, to evaluate the effect of temperature on the recurrence rate of convulsions. The cohort included four infants with low birth weight but with normal neonatal progress and 169 children born full term with a birth weight within the normal range. Patients with a fever higher than 38.5C were given paracetamol. Subjects were divided into three groups depending on the severity of the fever, as group 1 (> 40C), group 2 (39 - 39.9C), and group 3 (38 - 38.9C). Nineteen children were withdrawn from the study as 15 were lost to follow-up and four developed afebrile convulsions resulting in a final cohort of 154 children, who were evaluated for a mean of 40 months at three monthly intervals. Twenty-four children suffered from bacterial infections with 12 patients located at group 1, 10 within group 2, and two in group 3. None of the 11 patients who suffered from initial febrile convulsions following the age of 30 months experienced recurrence. However, the mean of recurrences was found to be 3.0 (range 2 - 7) arising in children aged one to 22 months following the initial episode. Out of the 47 patients, 28 were found to suffer from recurrences within six months. El-Radhi and Banajeh (1989) proposed that at the time of primary febrile convulsions, the degree of fever could be used as an informative tool revealing the risk of recurrence of febrile convulsions.

Qatar

In a study carried out to understand the incidence of recurrence and risk factors for febrile convulsions in Qatar, Bessisso et al. (2001) collected data on all children admitted with febrile seizures in a one-year period. A total of 236 children (128 males, 106 females; mean age of onset: 19 months) were recruited for the study. Of these, 66 patients (31%) were born to consanguineous parents, and 53 (22%) had a positive family history of the condition. This positive family history was more common among brothers (17%), and sisters (29%). Among the relatives of affected patients, epilepsy rate was found to be about 7%. The convulsions recurred within a year of onset in 52 (22%) patients. Within this sub-group of patients with recurrence, 23 patients had a positive family history of febrile convulsions, while 5 patients had a family history of epilepsy. The study also identified abnormal births (19.5%), gestational problems (16.5%), neonatal problems (15.5%), and prematurity (9.5%) in some of the patients. Apart from family history, the presence of complex febrile seizures, gender (boys outnumbering girls), and low grade temperature at the time of seizure (<38.5 C) were found to be other significant factors affecting recurrence.

United Arab Emirates

In 2006, Bener and colleagues undertook a matched case control study of all cases of febrile convulsions in UAE national children between the ages of 3 and 36 months diagnosed during a five year period (1998-2002) in Al Ain. Parents of a total of 70 patients were interviewed, and medical records of these patients examined. The highest frequencies of febrile convulsions were found between 1 and 2-years of age. Recurrent febrile seizures were noticed in 34.3% of the cases. Positive family history was found to be a significant predictor of the condition, with 21.4% of the cases showing a positive family history of febrile convulsions. In addition, 11.4% also had a positive family history of epilepsy. Five family pedigrees could be drawn. Two of these pedigrees indicated an autosomal dominant inheritance of the condition, with vertical transmission and apparent skipping of generations. Bener et al. (2006) explained the skipping of generations as possibly being due to reduced penetrance and variable expression of the responsible gene. Significant predictors of febrile seizures in this population were found to be sex (males being more susceptible), respiratory infection, positive family history, and birth weight using the Mantel-Haenszel test.

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