PADDAS syndrome associated with hair dysplasia caused by a de novo missense variant of PUM1

Epilepsy and Cognitive Impairment in Childhood and Adolescence: A Mini-Review

Managing epilepsy in people with an intellectual disability remains a therapeutic challenge and must take into account additional issues such as diagnostic difficulties and frequent drug resistance. Advances in genomic technologies improved our understanding of epilepsy and raised the possibility to develop patients-tailored treatments acting on the key molecular mechanisms involved in the development of the disease. In addition to conventional antiseizure medications (ASMs), ketogenic diet, hormone therapy and epilepsy surgery play an important role, especially in cases of drugresistance. This review aims to provide a comprehensive overview of the mainfactors influencing cognition in children and adolescents with epilepsy and the main therapeutic options available for the epilepsies associated with intellectual disability.

The role of altered translation in intellectual disability and epilepsy

A very high proportion of cases of intellectual disability are genetic in origin and are associated with the occurrence of epileptic seizures during childhood. These two disorders together effect more than 5% of the world's population. One feature linking the two diseases is that learning and memory require the synthesis of new synaptic components and ion channels, while maintenance of overall excitability also requires synthesis of similar proteins in response to altered neuronal stimulation. Many of these disorders result from mutations in proteins that regulate mRNA processing, translation initiation, translation elongation, mRNA stability or upstream translation modulators. One theme that emerges on reviewing this field is that mutations in proteins that regulate changes in translation following neuronal stimulation are more likely to result in epilepsy with intellectual disability than general translation regulators with no known role in activity-dependent changes. This is consistent with the notion that activity-dependent translation in neurons differs from that in other cells types in that the changes in local cellular composition, morphology and connectivity that occur generally in response to stimuli are directly coupled to local synaptic activity and persist for months or years after the original stimulus.

A de novo PUM1 Variant in a Girl With a Dravet-Like Syndrome: Case Report and Literature Review

In the recent 3 years, subjects with Pumilio1-associated developmental disability, ataxia, and seizure syndrome have been identified as harboring Pumilio homolog 1 (PUM1) mutations. However, the characteristics of the seizure phenotype remain to be elucidated. We herein described a 3-year-old female proband who was diagnosed with developmental and epileptic encephalopathy presenting with some features suggestive of a Dravet-like syndrome. For genetic analyses, trio-based whole-exome sequencing and array comparative genomic hybridization were performed. Consequently, a de novo heterozygous missense variant was identified in exon 22 of the PUM1 gene: NM_001020658: c.3439C > T (p.Arg1147Trp). Upon thoroughly reviewing the existing literature, nine cases of PUM1 mutation-related epilepsy were identified, and their clinical features were summarized. A relationship between PUM1 mutation and clinical manifestations characteristic of a Dravet-like syndrome was proposed. To our knowledge, this is the first report of a patient with PUM1 mutation presenting with a Dravet-like syndrome.

Investigating PUM1 mutations in a Taiwanese cohort with cerebellar ataxia

INTRODUCTION

Mutations in the PUM1 gene were recently identified to cause spinocerebellar ataxia type 47 (SCA47). However, their role in cerebellar ataxia in various populations remains elusive. The aim of this study was to elucidate the frequency and spectrum of PUM1 mutations in a cohort of Taiwanese patients with molecularly undetermined cerebellar ataxia.

METHODS

Mutational analyses of PUM1 were performed by Sanger sequencing in a cohort of 248 unrelated patients with cerebellar ataxia of unknown cause, including 108 with autosomal-dominantly inherited cerebellar ataxia, 45 with autosomal-recessively inherited cerebellar ataxia, and 95 with apparently sporadic cerebellar ataxia. Among them, the genetic causes of ataxia remained unknown after excluding mutations responsible for SCA1, 2, 3, 6, 7, 8, 10, 12, 17, 19/22, 23, 26, 27, 28, 31, 35, 36, dentatorubral-pallidoluysian atrophy and Friedreich's ataxia.

RESULTS

Two heterozygous missense PUM1 variants were identified in two patients with apparently sporadic cerebellar ataxia, including a known disease-causing mutation (p.R1139W) and a variant of uncertain significance (p.K151R). The patient carrying the p.R1139W mutation had a slowly progressive, relatively pure cerebellar ataxia, presenting with gait unsteadiness, limb dysmetria, ataxic dysarthria and saccadic pursuit.

CONCLUSION

Our findings support the pathogenic role of PUM1 mutations in cerebellar ataxia and emphasize the importance of considering PUM1 mutations as a possible etiology of cerebellar ataxia.