Migrating Focal Seizures and Myoclonic Status in ARV1-Related Encephalopathy

ARV1 Gene: A Novel Cause of Autosomal Recessive Cerebellar Ataxia with Elevated Alpha Fetoprotein

ARV1 mutation is known to present as developmental and epileptic encephalopathy (DEE)-38. However, the phenotypic spectrum has been expanding ever since it was reported in 2016. Along with seizures and developmental delay, other unique clinical features include ophthalmological abnormalities and movement disorders in the form of ataxia and dystonia, especially in those with missense mutation. These manifestations closely mimic ataxia telangiectasia. Elevation of alpha-fetoprotein levels is an important investigative marker in the diagnosis of ataxia telangiectasia and ataxia with oculomotor apraxia syndromes. ARV1 can also be associated with increased alpha-fetoprotein. There are no reports evaluating alpha-fetoprotein levels in cases with ARV1 mutation, which is significant in the context of ocular abnormalities with ataxia. We report a case of ARV1 mutation presenting with ataxia, ocular abnormalities, and elevated alpha-fetoprotein levels, thus mimicking autosomal recessive cerebellar ataxias. This study provides a comprehensive literature review of the cases reported so far, thus expanding the understanding of the spectrum of presentation, and helps in correlating the clinical picture with the underlying causative genetic mutation. ARV1 gene is another example of one gene with phenotypic pleiotropy. Though presentation with DEE is common, a few, especially those with missense mutations, can present with ataxia and ocular abnormalities. All cases presenting with ataxia who have increased alpha-fetoprotein levels and seizures should be tested for the ARV1 gene, when testing for ataxia genes is negative. The underlying genetic mechanism can explain the varying clinical manifestations of the ARV1 gene.

Progressive Myoclonus Epilepsy: A Scoping Review of Diagnostic, Phenotypic and Therapeutic Advances

The progressive myoclonus epilepsies (PME) are a diverse group of disorders that feature both myoclonus and seizures that worsen gradually over a variable timeframe. While each of the disorders is individually rare, they collectively make up a non-trivial portion of the complex epilepsy and myoclonus cases that are seen in tertiary care centers. The last decade has seen substantial progress in our understanding of the pathophysiology, diagnosis, prognosis, and, in select disorders, therapies of these diseases. In this scoping review, we examine English language publications from the past decade that address diagnostic, phenotypic, and therapeutic advances in all PMEs. We then highlight the major lessons that have been learned and point out avenues for future investigation that seem promising.

Severe Epilepsy and Movement Disorder May Be Early Symptoms of TMEM106B-Related Hypomyelinating Leukodystrophy

Objective

To report the clinical presentation of the first Italian child affected by hypomyelinating leukodystrophy (HLD) associated with the recurrent variant p.Asp252Asn in the TMEM106B gene.

Methods

The methods included clinical case description, neurophysiologic assessment, brain MRI, and whole-exome sequencing (WES).

Results

The child presented soon after birth with nystagmus and hyperkinetic movement disorder. Focal seizures appeared from 2 months of age and recurred at high frequency, despite several antiseizure medications, and focal epileptic status frequently required IV phenytoin. Control of seizures was achieved at the age of 8 months by the association of high doses of sodium blockers. Clinical picture worsened over time and was characterized by axial hypotonia, failure to thrive requiring gastrostomy, pyramidal sings, and severe secondary microcephaly. MRI performed at ages 2, 6, and 20 months showed diffuse supratentorial and subtentorial hypomyelination; multimodal evoked potentials showed increased latency. WES performed at 6 months of age identified the p.Asp252Asn de novo variant in the TMEM106B gene.

Discussion

Hyperkinetic movement disorders and seizures may be early symptoms of TMEM106B-HLD. Our observation, supported by video EEG recordings, emphasizes that seizures may be difficult to recognize from movement disorders and that epilepsy may be a severe and prominent symptom of the disease. TMEM106B-HLD should be considered in the genetic screening of infants with early-onset seizures and movement disorders.

Dilated cardiomyopathy is a part of the ARV1-associated phenotype: a case report

Background

ACAT-related enzyme 2 required for viability 1 (ARV1) encodes a transmembrane lipid transporter of the endoplasmic reticulum, which is presented in all eukaryotes and in plants. Deficiency of ARV1 is clinically presented as autosomal recessive developmental and epileptic encephalopathy 38 (DEE38) in humans and in mice. So far, three different homozygous and two compound heterozygous ARV1 mutations in humans have been reported in 15 children.

Case presentation

In this case report we present a novel homozygous in-frame ARV1-deletion (c.554_556delTAT, p.L185del) in a 21-year old Caucasian man with developmental delay, intellectual disability, seizures, walking and speech impairments, as well as with a dilated cardiomyopathy (DCM), which has not yet been firmly related to the ARV1-associated phenotype. Interestingly, this novel variant lies in the proximity of the p.G189R mutation, which was previously described in two brothers with DEE38 and dilated cardiomyopathy.

Conclusion

The finding of dilated cardiomyopathy in the presented as well as in three previously reported patients from two different families indicates that dilated cardiomyopathy is a part of the ARV1-induced DEE38 phenotype. However, more data are needed to make this conclusion definitive.

Spectrum of Neurological Symptoms in Glycosylphosphatidylinositol Biosynthesis Defects: Systematic Review

Background: Mutations of genes involved in the synthesis of glycosylphosphatidylinositol and glycosylphosphatidylinositol-anchored proteins lead to rare syndromes called glycosylphosphatidylinositol-anchored proteins biosynthesis defects. Alterations of their structure and function in these disorders impair often fundamental processes in cells, resulting in severe clinical image. This study aimed to provide a systematic review of GPIBD cases reports published in English-language literature.

Methods: The browsing of open-access databases (PubMed, PubMed Central. and Medline) was conducted, followed by statistical analysis of gathered information concerning neurological symptomatology. The inclusion criteria were: studies on humans, age at onset (<18 y.o.), and report of GPIBD cases with adequate data on the genetic background and symptomatology. Exclusion criteria were: publication type (manuscripts, personal communication, review articles); reports of cases of GPI biosynthesis genes mutations in terms of other disorders; reports of GPIBD cases concentrating on non-neurological symptoms; or articles concentrating solely on the genetic issues of GPI biosynthesis. Risk of bias was assessed using Joanna Brigs Institute Critical Appraisal Checklists. Data synthesis was conducted using STATISTICA 13.3.721.1 (StatSoft Polska Sp. z.o.o.). Used tests were chi-square, Fisher's exact test (for differences in phenotype), and Mann-Whitney U test (for differences in onset of developmental delay).

Results: Browsing returned a total of 973 articles which, after ruling out the repetitions and assessing the inclusion and exclusion criteria, led to final inclusion of 77 articles (337 GPIBD cases) in the analysis. The main outcomes were prevalence of neurological symptoms, onset and semiology of seizures and their response to treatment, and onset of developmental delay. Based on this data a synthesis of phenotypical differences between the groups of GPIBD cases and the general GPIBD cases population was made.

Discussion: A synthetical analysis of neurological components in clinical image of GPIBD patients was presented. It highlights the main features of these disorders, which might be useful in clinical practice for consideration in differential diagnosis with children presenting with early-onset seizures and developmental delay. The limitation of this review is the scarcity of the specific data in some reports, concerning the semiology and onset of two main features of GPIBD.