Whole exome sequencing identifies variable expressivity of CLN6 variants in Progressive myoclonic epilepsy affected families

Progressive myoclonic epilepsies (PMEs) are a group of neurodegenerative disorders, predominantly affecting adolescents and, characterized by generalized worsening myoclonus epilepsies, ataxia, cognitive deficits, and dementia. To date, several genes, having implications in diverse phenotypic expressions associated with PMEs, have been identified. Genetic diagnosis is available for most of the adolescence-onset myoclonic epilepsies. This study aimed to elucidate the genetic basis of PMEs in three multiplex Pakistani families exhibiting clinically variable phenotypes. Causative variant(s) in the studied families, and mode of segregation were identified by Whole Exome Sequencing (WES) of the probands, followed by bi-directional Sanger sequencing for final validation. We identified homozygous recessive CLN6 missense variant c.768 C>G (p.Asp256Glu) in Family 1, and c.889 C>A (p.Pro297Thr) variant in Family 2. While in Family 3, we found a homozygous variant (c.316dup) that caused a frameshift mutation, leading to a premature stop codon in the CLN6 protein, resulting in a truncated protein (p.Arg106ProfsTer26). Though CLN6 is previously identified to underlie late infantile and adolescent onset neuronal ceroid lipofuscinosis, this study supports and expands the phenotypic spectrum of CLN6 mutations and signifies diagnositc potential CLN6 variants for PMEs. Diverse pathological effects of variant c .768 C>G were observed in Family 1, with same genotypes, suggesting clinical heterogeneity and/or variable expressivity that might be the implication of pleiotropic effects of the gene in these cases.

Compound heterozygous variants in GOSR2 associated with congenital muscular dystrophy: A case report

The homozygous missense variant in the GOSR2 gene (c.430G > T) is known to be associated with progressive myoclonic epilepsy (PME). The clinical presentation of GOSR2-related PME involves the development of ataxia, seizures, scoliosis, areflexia, and mildly elevated creatine kinase. Recently, it has been suggested that some compound heterozygous variants in GOSR2 are associated with a predominant muscular dystrophy phenotype. Here we report a case of a now 22 month old female who presented with congenital hypotonia and persistently elevated creatine kinase levels. Whole exome sequencing showed pathogenic compound heterozygous variants in GOSR2 (c.430G > T and c.82C > T). This case contributes to the expanding clinical spectrum of GOSR2 variants with PME representing the milder end and congenital muscular dystrophy representing the more severe end of the spectrum.

Successful Treatment with Olanzapine of Psychosis in Dentatorubral-pallidoluysian Atrophy: A Case Report

Patients with dentatorubral-pallidoluysian atrophy occasionally elicit psychosis. So far, one study reported first generation antipsychotics drugs may provide an effective treatment; however, there is no literature on the benefits of second generation antipsychotics. We report on a 44-year-old man with dentatorubral-pallidoluysian atrophy whose psychotic symptoms were effectively treated with olanzapine. Our observation suggests some second generation antipsychotics provide a therapeutic option for ameliorating psychosis in dentatorubral-pallidoluysian atrophy.

[Lafora disease presentation, two cases in a Mexican family]

Myoclonic epilepsy, described in 1911 by Lafora and Glueck, is an autosomal recessive hereditary clinical-pathological entity, which begins at the end of childhood or during adolescence, presents atypical absences, generalized and atonic tonic-clonic seizures, which can evolve to the epileptic state. The diagnosis is confirmed trough the skin biopsy or trough determination of the protein laforine. In this paper we present the initial case of a patient in whom we confirm the diagnosis of progressive myoclonic epilepsy and in particular the Lafora disease, which due to the symptomatology and the knowledge of the case we were able to detect her sister's disease. Skin biopsies are reported with high sensitivity and specificity, observing inclusion bodies, and neurophysiological and electroencephalographic studies are undoubtedly non-specific. The article reports on the cases of two sisters, who were definitively confirmed their diagnosis, which allowed us to focus on the early detection of the other case.