A high frequency of the MTHFR 677C>T polymorphism in Scottish women with epilepsy: Possible role in pathogenesis

The inheritance of most forms of epilepsy is usually considered to be multifactorial, although a number of single gene causes are known. Most previous studies of epilepsy genetics have implicated ion channel genes or ligand receptors. In a previous study of children with adverse effects of prenatal exposure to antiepileptic drugs, we noted an increased frequency of the methylene tetrahydrofolate reductase (MTHFR) 677C>T polymorphism in the mothers. To investigate this further, a new cohort of women with epilepsy has been identified from maternity hospital records and genotyped for polymorphisms in MTHFR, serine hydroxymethyl transferase (SHMT1), methionine synthase (MTR) and methionine synthase reductase (MTRR). Healthy blood donors were genotyped as controls. The frequency of the MTHFR 677TT genotype was significantly higher in women with idiopathic generalised epilepsy than in healthy controls (p=0.012, OR 2.26, 95%CI 1.13-4.51). No association was detected for the other polymorphisms tested. The MTHFR 677C>T polymorphism may be a susceptibility factor for epilepsy, and its higher frequency in women with epilepsy may contribute to the increased risk of malformation in children of women with epilepsy.

Characteristics of fetal anticonvulsant syndrome associated autistic disorder

The aim of this study was to evaluate the clinical features and frequency of autistic disorder or Asperger syndrome (AS; according to Diagnostic and Statistical Manual of Mental Disorders, 4th edition [DSM-IV] criteria) in children exposed to anticonvulsant medication in utero. During a 20-year study period, 626 children were born in Aberdeen to mothers taking antiepileptic drugs (AEDs). The study examined long-term effects of prenatal exposure to AEDs in 260 children (122 males, 138 females). Of these, 26 (16 males) were reported by parents to have social or behavioural difficulties. Eleven children (6 males, 5 females) fulfilled the DSM-IV criteria for autistic disorder and one (female) fulfilled the DSM-IV criteria for AS. These children comprised 4.6% of the exposed children studied, and 1.9% of all exposed children born during the study period. Mean age of these children at diagnosis was 5 years 4 months (SD 2y 11mo) and 9 years 10 months (SD 3y 10mo) at the time of this study. Other children from the group of 26 had difficulties in areas of speech and language development and social communication but did not meet the criteria for an autism spectrum disorder (ASD). Sodium valproate was the drug most commonly associated with autistic disorder, five of 56 (8.9%) of the study children exposed to sodium valproate alone had either autistic disorder or AS. It was concluded that prenatal exposure to anticonvulsant medication is a risk factor for the development of an ASD. Fetal anticonvulsant syndrome associated autistic disorder is characterized by an even sex ratio, absence of regression or skill loss, and language delay in the absence of global delay.

Long term health and neurodevelopment in children exposed to antiepileptic drugs before birth

OBJECTIVE

To investigate the frequency of neonatal and later childhood morbidity in children exposed to antiepileptic drugs in utero.

DESIGN

Retrospective population based study.

SETTING

Population of the Grampian region of Scotland.

PARTICIPANTS

Mothers taking antiepileptic drugs in pregnancy between 1976 and 2000 were ascertained from hospital obstetric records and 149 (58% of those eligible) took part. They had 293 children whose health and neurodevelopment were assessed.

MAIN OUTCOME MEASURES

Frequencies of neonatal withdrawal, congenital malformations, childhood onset medical problems, developmental delay, and behaviour disorders.

RESULTS

Neonatal withdrawal was seen in 20% of those exposed to antiepileptic drugs. Congenital malformations occurred in 14% of exposed pregnancies, compared with 5% of non-exposed sibs, and developmental delay in 24% of exposed children, compared with 11% of non-exposed sibs. After excluding cases with a family history of developmental delay, 19% of exposed children and 3% of non-exposed sibs had developmental delay, 31% of exposed children had either major malformations or developmental delay, 52% of exposed children had facial dysmorphism compared with 25% of those not exposed, 31% of exposed children had childhood medical problems (13% of non-exposed sibs), and 20% had behaviour disorders (5% of non-exposed).

CONCLUSION

Prenatal antiepileptic drug exposure in the setting of maternal epilepsy is associated with developmental delay and later childhood morbidity in addition to congenital malformation.