Clinical and genetic features of acute encephalopathy in children taking theophylline.

BACKGROUND: Theophylline has recently been suspected as a risk factor of acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), although there has been no systematic study on the relationship between acute encephalopathy in children taking theophylline (AET) and AESD. METHODS: We recruited 16 Japanese patients (11 male and 5 female, median age of 2 years and 7 months) with AET from 2008 to 2013. We evaluated their clinical features, such as the duration of first seizure, biphasic clinical course and cranial CT/MRI imaging and compared them with those of AESD. We analyzed the polymorphisms or mutations of genes which are associated with AESD. RESULTS: Clinically, 12 patients had neurological and/or radiological features of AESD. Only one patient died, whereas all 15 surviving patients were left with motor and/or intellectual deficits. Genetically, 14 patients had at least one of the following polymorphisms or mutations associated with AESD: thermolabile variation of the carnitine palmitoyltransferase 2 (CPT2) gene, polymorphism causing high expression of the adenosine receptor A2A (ADORA2A) gene, and heterozygous missense mutation of the voltage gated sodium channel 1A (SCN1A) and 2A (SCN2A) gene. CONCLUSIONS: Our results demonstrate that AET overlaps with AESD, and that AET is a multifactorial disorder sharing a genetic background with AESD.

A case of recurrent acute encephalopathy with febrile convulsive status epilepticus with carnitine palmitoyltransferase II variation.

Acute encephalopathy with febrile convulsive status epilepticus (AEFCSE) is the most common type of acute encephalopathy in childhood in Japan, which develops with prolonged febrile convulsion, followed by mild unconsciousness. It is generally sporadic and nonrecurrent. In this report, a 1-year-old girl showed signs of AEFCSE triggered by respiratory syncytial virus infection. Two years later, she presented with AEFCSE triggered by influenza virus infection, resulting in severe neurologic sequelae. The patient had a thermolabile genotype of carnitine palmitoyltransferase II (CPT II) variations consisting of three single nucleotide polymorphisms in exons 4 [1055T > G/F352C and 1102G > A/V368I] and 5 [1939A > G/M647V]. The polymorphism has been identified as a genetic predisposition for acute encephalopathy. This report presents the first case of recurrent encephalopathy with CPT II variations that may partially associate with pathogenesis of recurrent AEFCSE.

ADORA2A polymorphism predisposes children to encephalopathy with febrile status epilepticus.

OBJECTIVE: Acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) is a childhood encephalopathy following severe febrile seizures, leaving neurologic sequelae in many patients. However, its pathogenesis remains unclear. In this study, we clarified that genetic variation in the adenosine A2A receptor (ADORA2A), whose activation is involved in excitotoxicity, may be a predisposing factor of AESD. METHODS: We analyzed 4 ADORA2A single nucleotide polymorphisms in 85 patients with AESD. The mRNA expression in brain samples, mRNA and protein expression in lymphoblasts, as well as the production of cyclic adenosine monophosphate (cAMP) by lymphoblasts in response to adenosine were compared among ADORA2A diplotypes. RESULTS: Four single nucleotide polymorphisms were completely linked, which resulted in 2 haplotypes, A and B. Haplotype A (C at rs2298383, T at rs5751876, deletion at rs35320474, and C at rs4822492) frequency in patients was significantly higher than in controls (p = 0.005). Homozygous haplotype A (AA diplotype) had a higher risk of developing AESD (odds ratio 2.32, 95% confidence interval 1.32-4.08; p = 0.003) via a recessive model. mRNA expression was significantly higher in AA than AB and BB diplotypes, both in the brain (p = 0.003 and 0.002, respectively) and lymphoblasts (p = 0.035 and 0.003, respectively). In lymphoblasts, ADORA2A protein expression (p = 0.024), as well as cellular cAMP production (p = 0.0006), was significantly higher in AA than BB diplotype. CONCLUSIONS: AA diplotype of ADORA2A is associated with AESD and may alter the intracellular adenosine/cAMP cascade, thereby promoting seizures and excitotoxic brain damage in patients.

Acute encephalopathy with a novel point mutation in the SCN2A gene.

Mutations of the neuronal voltage-gated sodium channel alpha subunit type II (SCN2A) cause various epileptic syndromes, but have never been reported in association with acute encephalopathy. To validate the involvement of SCN2A mutations in acute encephalopathy, we screened 25 patients and found a novel missense mutation (Met1128Thr) in a patient with acute encephalitis with refractory, repetitive partial seizures (AERRPS). This finding suggests that SCN2A mutation is a predisposing factor for acute encephalopathy.

Mutations of the SCN1A gene in acute encephalopathy.

PURPOSE: Acute encephalopathy is the most serious complication of pediatric viral infections, such as influenza and exanthema subitum. It occurs worldwide, but is most prevalent in East Asia. Recently, there have been sporadic case reports of epilepsy/febrile seizure and acute encephalopathy with a neuronal sodium channel alpha 1 subunit (SCN1A) mutation. To determine whether SCN1A mutations are a predisposing factor of acute encephalopathy, we sought to identify SCN1A mutations in a large case series of acute encephalopathy including various syndromes. METHODS: We analyzed the SCN1A gene in 87 patients with acute encephalopathy, consisting of 20 with acute necrotizing encephalopathy (ANE), 61 with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD), and six with nonspecific (unclassified) acute encephalopathy. KEY FINDINGS: Three patients had distinct point mutations. Two of them had epileptic seizures prior to acute encephalopathy. Clinical and neuroradiologic findings of acute encephalopathy were diverse among the three patients, although all had a prolonged and generalized seizure at its onset. The first patient with V982L had partial epilepsy and AESD. The second patient with M1977L had febrile seizures and nonspecific acute encephalopathy. The third patient with R1575C had no seizures until the onset of ANE. M1977L was a novel mutation, whereas the remaining two, V982L and R1575C, have previously been reported in cases of Dravet syndrome and acute encephalopathy, respectively. SIGNIFICANCE: These findings provide further evidence that SCN1A mutations are a predisposing factor for the onset of various types of acute encephalopathy.

Carnitine palmitoyl transferase II polymorphism is associated with multiple syndromes of acute encephalopathy with various infectious diseases.

The high incidence of acute encephalopathy in East Asia suggests the role of genetic factors in its pathogenesis. It has recently been reported that variations of the CPT II (carnitine palmitoyl transferase II) gene may be associated with fatal or severe cases of influenza-associated encephalopathy. In the present study, we examined the genotype of CPT II in cases of acute encephalopathy associated with various preceding infections. Twenty-nine Japanese patients with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD) or acute necrotizing encephalopathy (ANE) were studied. The frequency of F352C of CPT II exon 4 was significantly higher in patients than in controls. All patients who had allele C in F352C had allele I in V368I and allele M in M647V (CIM haplotype), which reportedly decreases CPT II activity to one third of that with FIM or FVM haplotype. The frequency of CIM haplotype was significantly different between patients and controls, but not between AESD and ANE. Our results revealed that having at least one CIM allele is a risk factor for the onset of acute encephalopathy, regardless of its antecedent infections.