UNASSIGNED: This study presents the clinical phenotypes and genetic analysis of seven patients with benign familial infantile epilepsy (BFIE) diagnosed by whole-exome sequencing.
UNASSIGNED: The clinical data of seven children with BFIE diagnosed at the Department of Neurology, Children\'s Hospital Affiliated to Zhengzhou University between December 2017 and April 2022 were retrospectively analyzed. Whole-exome sequencing was used to identify the genetic causes, and the variants were verified by Sanger sequencing in other family members.
UNASSIGNED: The seven patients with BFIE included two males and five females ranging in age between 3 and 7 months old. The main clinical phenotype of the seven affected children was the presence of focal or generalized tonic-clonic seizures, which was well controlled by anti-seizure medication. Cases 1 and 5 exhibited predominantly generalized tonic-clonic seizures accompanied by focal seizures while cases 2, 3, and 7 displayed generalized tonic-clonic seizures, and cases 4 and 6 had focal seizures. The grandmother and father of cases 2, 6, and 7 had histories of seizures. However, there was no family history of seizures in the remaining cases. Case 1 carried a de novo frameshift variant c.397delG (p.E133Nfs*43) in the proline-rich transmembrane protein 2 (PRRT2) gene while case 2 had a nonsense variant c.46G > T (p.Glu16*) inherited from the father, and cases 3-7 carried a heterozygous frameshift variant c.649dup (p.R217Pfs*8) in the same gene. In cases 3 and 4, the frameshift variant was de novo, while in cases 5-7, the variant was paternally inherited. The c.397delG (p.E133Nfs*43) variant is previously unreported.
UNASSIGNED: This study demonstrated the effectiveness of whole-exome sequencing in the diagnosis of BFIE. Moreover, our findings revealed a novel pathogenic variant c.397delG (p.E133Nfs*43) in the PRRT2 gene that causes BFIE, expanding the mutation spectrum of PRRT2.

Self-limited infantile epilepsy (SeLIE) has distinctive clinical features, and the PRRT2 gene is known to be a considerable genetic cause. There have been a few studies on PRRT2-positive SeLIE only, and anti-seizure medications are often required due to frequent seizures at initial seizure onset. This study aimed to provide clinical information for the early recognition of patients with PRRT2-positive SeLIE and to propose effective anti-seizure medications for seizure control.
We retrospectively reviewed 36 patients diagnosed with SeLIE with genetically confirmed pathogenic variants of PRRT2. In addition, six atypical cases with neonatal-onset seizures and unremitting after 3 years of age were included to understand the expanded clinical spectrum of PRRT2-related epilepsy. We analyzed the initial presentation, clinical course, and seizure control response to anti-seizure medications.
Patients with PRRT2-related epilepsy had characteristic seizure semiology at the initial presentation, including all afebrile, clustered (n = 23, 63.9%), short-duration (n = 33, 91.7%), and bilateral tonic-clonic seizures (n = 26, 72.2%). Genetic analysis revealed that c. 649dupC was the most common variant, and six patients had a 16p11.2 microdeletion containing the PRRT2 gene. One-third of the patients were sporadic cases without a family history of epilepsy or paroxysmal movement disorders. In the 33 patients treated with anti-seizure medications, sodium channel blockers, such as carbamazepine, were the most effective in seizure control.
Our results delineated the clinical characteristics of PRRT2-positive SeLIE, differentiating it from other genetic infantile epilepsies and discovered the effective anti-seizure medications for initial clustered seizure control. If afebrile bilateral tonic-clonic seizures develop in a normally developed infant as a clustered pattern, PRRT2-positive SeLIE should be considered as a possible diagnosis, and sodium channel blockers should be administered as the first medication for seizure control.

Paroxysmal kinesigenic dyskinesia (PKD) is characterized by transient and recurrent involuntary movements that are triggered by a sudden movement. Here, we report an elderly female patient with a 1-month history of paroxysmal rigidity of the right limb. As the symptoms were characterized as paroxysmal, transient, and repetitive, her condition was initially thought to be epilepsy. Subsequent examinations showed no abnormality in the continuous video-electroencephalogram (EEG) monitoring, magnetic resonance imaging (MRI), fluorodeoxyglucose (FDG)-positron emission tomography (PET)/computed tomography (CT), and genetic testing. The final diagnosis was identified as clinically diagnosed PKD, and the symptoms were well controlled after oxcarbazepine treatment. To our knowledge, this is the first report to show elderly-onset PKD. This case expands our understanding of the age of onset of PKD. However, it is necessary to differentiate PKD from reflex epilepsy and hysteria attacks. For patients with typical clinical manifestations, we should adhere to the standard diagnostic workflow for the efficient diagnosis of PKD, aiming at avoiding misdiagnosis and mistreatment.

In a three-generation family, five individuals exhibited the typical phenotype of paroxysmal kinesigenic dyskinesia (PKD). Intriguingly, one of the individuals also showed benign familial infantile convulsions (BFIC) at age 4 months and spontaneously resolved at age 18 months. At age 12, she developed a typical PKD, and was gradually relieved at age 21. Therefore, the clinical phenotype was consistent with PKD with infantile convulsions (PKD/IC). Whole exome sequence and co-segregation analysis revealed a novel heterozygous variant c.1085A > G in the TMEM151A gene. Our study suggests that the TMEM151A gene may be associated with the disease spectrum of PKD-PKD/IC-BFIC.

A clinical case of a patient with neonatal epilepsy at the age of 5 months, with impaired bone formation, early osteoporosis and frequent limb fractures is described. Panel sequencing confirmed by Sanger sequencing revealed two independent hereditary diseases - osteogenesis imperfect type 1, associated with a mutation in the COL1A1 gene (c.2010delT) and benign non-familial infantile seizures associated with a mutation in the PRRT2 gene (c.649dupC). A unique clinical case of a combination of these diseases is presented.
Описан клинический случай пациента с неонатальной эпилепсией в возрасте 5 мес жизни, с нарушением формирования костной ткани, ранним остеопорозом и частыми переломами конечностей. Методами панельного секвенирования и подтверждающего секвенирования по Сэнгеру выявлены две независимые наследственные болезни — несовершенный остеогенез 1-го типа, ассоциированный с мутацией в гене COL1A1 (с.2010delT), и доброкачественные несемейные инфантильные приступы, ассоциированные с мутацией в гене PRRT2 (c.649dupC). Представлен уникальный клинический случай сочетания данных заболеваний.

Mutations of the PRRT2 gene are the most common cause for paroxysmal kinesigenic dyskinesia. However, patients with negative PRRT2 mutations are not rare. The aim of this study is to determine whether copy number variant of PRRT2 gene is another potential pathogenic mechanism in the patients with paroxysmal kinesigenic dyskinesia with negative PRRT2 point and frameshift mutations.
We screened PRRT2 copy number variants using the AccuCopy™ method in 29 patients with paroxysmal kinesigenic dyskinesia with negative PRRT2 point and frameshift mutations. Next-generation sequencing was used to determine the chromosomal deletion sites in patients with PRRT2 copy number variants, and to exclude mutations in other known causative genes for paroxysmal kinesigenic dyskinesia.
Two sporadic patients with negative PRRT2 point and frameshift mutations (6.9%) were identified to have de novo PRRT2 copy number deletions (591 and 832 Kb deletions located in 16p11.2). The two patients presented with pure paroxysmal kinesigenic dyskinesia and paroxysmal kinesigenic dyskinesia and benign infantile convulsions, respectively. They had normal intelligence and neuropsychiatric development, in contrast to those previously reported with 16p11.2 deletions complicated with neuropsychiatric disorders. No correlation between the deletion ranges and phenotypic variations was found.
16p11.2 deletions play causative roles in paroxysmal kinesigenic dyskinesia, especially for sporadic cases. Our findings extend the phenotype of 16p11.2 deletions to pure paroxysmal kinesigenic dyskinesia. Screening for 16p11.2 deletions should thus be included in genetic evaluations for patients with paroxysmal kinesigenic dyskinesia.

OBJECTIVE: To describe the clinical spectrum of benign nocturnal alternating hemiplegia of childhood (BNAHC) including long-term follow-up data of previously published cases and to propose an underlying genetic cause of this disorder.
METHODS: We studied the medical data of two novel patients, reviewed the literature on BNAHC, and gathered information of the most recent follow-up of published cases regarding the course of episodes, further development, attempted drugs, ancillary investigations, and sequelae.
RESULTS: All patients, i.e. two novel cases and twelve patients identified in the literature (13 boys, 1 girl, age at onset four months to three years), experienced episodes of hemiplegia during nocturnal or daytime sleep heralded by inconsolable crying. Possible triggers included stress and sleep deprivation. Eleven of fourteen patients had a family history of migraine or \'intermittent headache\' and two sets of siblings are reported. In one case, exome sequencing revealed a heterozygous 16p11.2 deletion involving 33 genes, including the PRRT2 gene. EEG showed ictal and/or interictal contralateral slowing in four patients. Treatment efficacy was generally disappointing. A complete disappearance of attacks appeared in nearly all cases at most recent follow-up. In a remarkably high number of cases (10/14, 71%), hyperactive behaviour was reported during follow-up.
CONCLUSIONS: We underscore the phenotypic homogeneity including the self-limiting course of BNAHC episodes and suggest the condition be renamed \'benign childhood hemiplegia during sleep\' (BCHS). We propose a role for the PRRT2 gene and the resulting neuronal hyperexcitability as one of its possible underpinning mechanisms and discuss the clinical similarities of BCHS with the recognized PRRT2-related disorders.

UNASSIGNED: Paroxysmal kinesigenic dyskinesia (PKD) is characterized by sudden episodes of involuntary movements. PKD is a very rare movement disorder, and correct clinical diagnosis is often a challenge.
UNASSIGNED: We present the case of a 23-year-old female with PKD. The patient showed episodes of twisting movements for 3 years. The symptoms lasted for about 5-10 minutes and subsided spontaneously. She was diagnosed as having epilepsy, and depressive and anxiety disorders successively. However, her symptoms did not alleviate after taking sodium valproate and antidepressants. Though there were no mutations in her PRRT2 gene, carbamazepine was used for treatment and was effective in controlling her symptoms.
UNASSIGNED: The clinical features of PKD patients are not always typical; therefore, it is important to distinguish PKD from the other subtypes of paroxysmal dyskinesia and psychogenic disorders.

OBJECTIVE: Though rare, children are susceptible to paroxysmal dyskinesias such as paroxysmal kinesigenic dyskinesia, and infantile convulsions and choreoathetosis. Recent studies showed that the cause of paroxysmal kinesigenic dyskinesia or infantile convulsions and choreoathetosis could be proline-rich transmembrane protein 2 (PRRT2) gene mutations.
METHODS: This study analysed PRRT2 gene mutations in 51 families with paroxysmal kinesigenic dyskinesia or infantile convulsions and choreoathetosis by direct sequencing. In particular, we characterize the genotype-phenotype correlation between age at onset and the types of PRRT2 mutations in all published cases.
RESULTS: Direct sequencing showed that 12 out of the 51 families had three different pathogenic mutations (c.649dupC, c.776dupG, c.649C>T) in the PRRT2 gene. No significant difference of age at onset between the patients with and without PRRT2 mutations was found in this cohort of patients. A total of 97 different PRRT2 mutations have been reported in 87 studies till now. The PRRT2 mutation classes are wide, and most mutations are frameshift mutations but the most common mutation remains c.649dupC. Comparisons of the age at onset in paroxysmal kinesigenic dyskinesia or infantile convulsions patients with different types of mutations showed no significant difference.
CONCLUSIONS: This study expands the clinical and genetic spectrums of Chinese patients with paroxysmal kinesigenic dyskinesia and infantile convulsions and choreoathetosis. No clear genotype-phenotype correlation between the age at onset and the types of mutations has been determined.

Proline-rich transmembrane protein 2 gene (PRRT2) mutations are reported to cause common paroxysmal neurological disorders and show a remarkable pleiotropy. Benign epilepsy with centrotemporal spikes (BECTS) is considered to be the most common epilepsy syndrome in childhood. It is placed among the idiopathic localization related epilepsies. Recently, it was reported that a girl with a PRRT2 mutation c.649_650insC developed infantile focal epilepsy with bilateral spikes which resembled the rolandic spikes. Hereby we performed a comprehensive genetic mutation screening of PRRT2 gene in a cohort of 53 sporadic BECTS patients. None of the 53 sporadic BECTS patients and other 250 controls carried mutations including c.649_650insC in PRRT2. Our data indicated that the PRRT2 mutations might most likely not be associated with BECTS in Chinese mainland population.