Novel mutations in the Na+, K+-ATPase pump gene ATP1A2 associated with familial hemiplegic migraine and benign familial infantile convulsions

Familial hemiplegic migraine (FHM) is a rare, severe, autosomal dominant subtype of migraine with aura. Up to 75% of FHM families have a mutation in the P/Q-type calcium channel Ca(v)2.1 subunit CACNA1A gene on chromosome 19p13. Some CACNA1A mutations also may cause epilepsy. Here, we describe novel missense mutations in the ATP1A2 Na(+),K(+)-ATPase pump gene on chromosome 1q23 in two families with FHM. The M731T mutation was found in a family with pure FHM. The R689Q mutation was identified in a family in which FHM and benign familial infantile convulsions partially cosegregate. In this family, all available affected family members with FHM, benign familial infantile convulsions, or both, carry the ATP1A2 mutation. Like FHM linked to 19p13, FHM linked to 1q23 also involves dysfunction of ion transportation and epilepsy is part of its phenotypic spectrum.

Benign familial neonatal convulsions: always benign?

BACKGROUND

Benign familial neonatal convulsions (BFNC) is a rare autosomal dominant seizure disorder usually described to be characterized by a benign course, spontaneous remission and normal psychomotor development. The latter statement had come under consideration when a few case reports of families with less than favorable outcomes were published.

METHODS

Since 1998 a total of 112 families suspected to have BFNC have been referred to our lab for genetic testing. Within this sample we identified private KCNQ2 mutations in 17 BFNC families. For 10 of those 17 families follow up information about the psychomotor development and the outcome were available.

RESULTS

In 4 (40%) of the 10 families at least 1 affected individual showed delayed psychomotor development or mental retardation. Three of the four mutations were familial, while the fourth mutation was de novo. Mutations associated with an unfavorable outcome tended to be located within the functionally critical S5/S6 regions of the KCNQ2 gene.

CONCLUSIONS

Our data raise the question if BFNC can indeed be described as a benign disorder, and which are the genetic and/or environmental factors that influence the outcome.

The clinical conundrum of neonatal seizures

There is increasing evidence that neonatal seizures have an adverse effect on neurodevelopmental progression and may predispose to cognitive, behavioural, or epileptic complications later in life. However, given the uncertainty about the efficacy and toxicity of the commonly used anticonvulsants, when and how aggressively to treat such seizures is a difficult decision.

PRRT2-related disorders: further PKD and ICCA cases and review of the literature

Recent studies reported mutations in the gene encoding the proline-rich transmembrane protein 2 (PRRT2) to be causative for paroxysmal kinesigenic dyskinesia (PKD), PKD combined with infantile seizures (ICCA), and benign familial infantile seizures (BFIS). PRRT2 is a presynaptic protein which seems to play an important role in exocytosis and neurotransmitter release. PKD is the most common form of paroxysmal movement disorder characterized by recurrent brief involuntary hyperkinesias triggered by sudden movements. Here, we sequenced PRRT2 in 14 sporadic and 8 familial PKD and ICCA cases of Caucasian origin and identified three novel mutations (c.919C>T/p.Gln307, c.388delG/p.Ala130Profs 46, c.884G>A/p.Arg295Gln) predicting two truncated proteins and one probably damaging point mutation. A review of all published cases is also included. PRRT2 mutations occur more frequently in familial forms of PRRT2-related syndromes (80-100 %) than in sporadic cases (33-46 %) suggesting further heterogeneity in the latter. PRRT2 mutations were rarely described in other forms of paroxysmal dyskinesias deviating from classical PKD, as we report here in one ICCA family without kinesigenic triggers. Mutations are exclusively found in two exons of the PRRT2 gene at a high rate across all syndromes and with one major mutation (c.649dupC) in a mutational hotspot of nine cytosines, which is responsible for 57 % of all cases in all phenotypes. We therefore propose that genetic analysis rapidly performed in early stages of the disease is highly cost-effective and can help to avoid further unnecessary diagnostic and therapeutic interventions.

Seizure recurrence and developmental disabilities after neonatal seizures: outcomes are unrelated to use of phenobarbital prophylaxis

This study investigated treatment patterns at discharge in infants with neonatal seizures and evaluated the impact of outpatient phenobarbital prophylaxis on the frequency of seizure recurrence and the long-term neurodevelopmental outcome at 1 to 11 years. Infants with neonatal seizures during a 12-year period were identified retrospectively (n = 146), and data were obtained by medical chart review. Outcomes were ascertained by standardized telephone survey. Thirty-three infants (23%) were taking phenobarbital, and 99 infants (68%) were taking no anticonvulsants at discharge. Comparisons were made between these 2 groups. Phenobarbital prophylaxis did not improve neurologic outcomes, either with respect to seizure recurrence or neurologic development. These data have important implications at a time when many are questioning the practice of prophylaxis after neonatal seizures and when newer anticonvulsants are being recommended for treatment of acute neonatal seizures.

Epileptic negative myoclonus induced by carbamazepine in a child with BECTS. Benign childhood epilepsy with centrotemporal spikes

A 7-year-old female with benign childhood epilepsy with centrotemporal spikes developed epileptic negative myoclonus (ENM) seizures during carbamazepine (CBZ) treatment. She had experienced nocturnal partial seizures since 5 years of age. Interictal electroencephalography demonstrated typical rolandic discharges. Valproate was first initiated at 6 years of age, but the seizures were uncontrollable. Carbamazepine was added and valproate withdrawn. The frequency of partial seizures did not decrease. Moreover, she had brief episodes of tone loss in each or both arms and eye blinking several weeks after CBZ introduction. Unilateral loss of arm tone corresponded to spike-and-wave discharges in the contralateral centrotemporal region, and a loss of tone in arms was associated with bilateral synchronous discharges. Eye blinking was also related to bilateral synchronous discharges and classified as a myoclonic seizure. The ENM and myoclonic seizures disappeared soon after CBZ withdrawal. Therefore the authors concluded that CBZ induced the ENM and myoclonic seizures in this patient. CBZ sometimes induces generalized seizures in the treatment of partial epilepsy and generalized epilepsy. CBZ-induced ENM seizures should be considered when a brief lapse of tone appears during CBZ treatment.

Genetic analysis of PRRT2 for benign infantile epilepsy, infantile convulsions with choreoathetosis syndrome, and benign convulsions with mild gastroenteritis

PURPOSE

PRRT2 mutations were recently identified in benign familial infantile epilepsy (BFIE) and infantile convulsions with paroxysmal choreoathetosis (ICCA) but no abnormalities have so far been identified in their phenotypically similar seizure disorder of benign convulsions with mild gastroenteritis (CwG), while mutations in KCNQ2 and KCNQ3 have been recognized in benign familial neonatal epilepsy (BFNE). The aim of this study was to identify PRRT2 mutations in infantile convulsions in Asian families with BFIE and ICCA, CwG and BFNE.

METHODS

We recruited 26 unrelated Japanese affected with either BFIE or non-familial benign infantile seizures and their families, including three families with ICCA. A total of 17 Japanese and Taiwanese with CwG, 50 Japanese with BFNE and 96 healthy volunteers were also recruited. Mutations of PRRT2 were sought using direct sequencing.

RESULTS

Heterozygous truncation mutation (c.649dupC) was identified in 15 of 26 individuals with benign infantile epilepsy (52.1%). All three families of ICCA harbored the same mutation (100%). Another novel mutation (c.1012+2dupT) was found in the proband of a family with BFIE. However, no PRRT2 mutation was found in either CwG or BFNE.

CONCLUSIONS

The results confirm that c.649dupC, a truncating mutation of PRRT2, is a hotspot mutation resulting in BFIE or ICCA regardless of the ethnic background. In contrast, PRRT2 mutations do not seem to be associated with CwG or BFNE. Screening for PRRT2 mutation might be useful in early-stage differentiation of BFIE from CwG.

Ictal EEG in patients with convulsions with mild gastroenteritis

The aim of this study is to reveal detailed clinical manifestations and an evolution of ictal EEG discharges of convulsions with mild gastroenteritis (CwG). We recorded ictal EEGs of six patients with CwG. Clinical manifestations included loss of responsiveness, motion arrest, cyanosis, lateral eye deviation, and hemifacial convulsion. Automatism was not observed in any patients. A generalized tonic-clonic convulsion was observed in five of six patients. Ictal EEGs demonstrated that all seizures were of focal onset that evolved into a secondarily generalized seizure. The region of the onset of ictal discharge was the occipital area in three patients, parietal in one, central in one, and frontal in one, respectively. The seizure of patients with CwG is likely to be a partial seizure with secondary generalization.

Cardiovascular and neuroendocrine features of Panayiotopoulos syndrome in three siblings

OBJECTIVE

Panayiotopoulos syndrome is a benign idiopathic childhood epilepsy characterized by altered autonomic activity at seizure onset.

METHODS

Three siblings with Panayiotopoulos syndrome underwent 24-hour EEG recording and head-up tilt testing with continuous blood pressure and RR interval monitoring. Plasma catecholamines and vasopressin were measured while supine, upright, and during a typical seizure.

RESULTS

Patient 1, a 12-year-old girl, had a history of involuntary lacrimation, abdominal pain, and recurrent episodes of loss of muscle tone and unresponsiveness followed by somnolence. Her EEG revealed bilateral frontotemporal spikes. Patient 2, a 10-year-old boy, had episodic headaches with pinpoint pupils, skin flushing of the face, trunk, and extremities, purple discoloration of hands and feet, diaphoresis, nausea, and vomiting. Tilt testing triggered a typical seizure after 9 minutes; there was a small increase in blood pressure (+5/4 mm Hg, systolic/diastolic) and pronounced increases in heart rate (+59 bpm) and norepinephrine (+242 pg/mL), epinephrine (+175 pg/mL), and vasopressin (+22.1 pg/mL) plasma concentrations. Serum glucose was elevated (206 mg/dL). His EEG revealed right temporal and parietal spikes. Patient 3, an 8-year-old boy, had a history of restless legs at night, enuresis, night terrors, visual hallucinations, cyclic abdominal pain, and nausea. His EEG showed bitemporal spikes.

CONCLUSION

Hypertension, tachycardia, and the release of vasopressin suggest activation of the central autonomic network during seizures in familial Panayiotopoulos syndrome. These autonomic and neuroendocrine features may be useful in the diagnosis and may have therapeutic implications.

Time-frequency analysis of heart rate variability for neonatal seizure detection

The ECG has been much neglected in automatic seizure detection in the newborn. Changes in heart rate and ECG rhythm are often found in animal and adult patients with seizure. However, little is known about heart rate variability (HRV) changes in human neonate during seizure. Results of ongoing time-frequency research are presented here with the aim to compare the performance of various time-frequency distributions (TFDs) when applied to HRV time series for non-seizure and seizure newborns. The TFDs studied are the Wigner-Ville (WVD), the Spectrogram (SP), the Choi-Williams (CWD) and the Modified B (MBD) distributions. Based on our preliminary results, our current conclusion is MBD outperforms other TFDs in terms of time-frequency resolution, cross-terms suppression and to represent the newborn HRV signals of non-seizure and seizure which are closely-spaced components in the time-frequency domain.

[The effect of neonatal convulsions and antiepileptic drugs on the developing brain: controversial aspects and therapeutic implications]

INTRODUCTION

Neonatal seizures are the clinical or subclinical manifestations of epileptic nature during the first 28 days of life. Their pathophysiological basis depends on the anatomic and biochemical characteristics of the developing brain. The question whether neonatal seizures cause brain damage, even today, has not a clear answer.

DEVELOPMENT

Data from clinical cases suggest that neonatal seizures may increase the cerebral blood flow and augment the energy requirements of the developing brain. Clinical research studies also suggest that neonatal seizures, even when they are only electrographic, may cause brain lesion independently from their cause. Multiple experimental investigations using mostly rat models of isolated or repeated induced seizures, have demonstrated that neonatal seizures may alter brain metabolic content, maturation of glutamatergic and GABAergic receptors, future cognitive development and epileptogenic risk, neuroneogenesis, intranuclear penetration of calcium, and neuronal apoptotic activation. On the other hand, some experimental studies suggest that phenobarbital, phenytoin and benzodiazepines may have a negative effect on brain development.

CONCLUSIONS

In my opinion, the ideal short-term goal of treating neonatal seizures should be stopping not only the clinical but also the subclinical epileptic activity. If prolonged treatment is necessary, one should consider to stop it as soon as the clinical and EEG course allows it. There is a need for future randomized, controlled trials of sufficient statistical power to assess the efficacy and tolerability of classic and new antiepileptic drugs in the treatment of neonatal seizures.