Variant in CACNA1G as a Possible Genetic Modifier of Neonatal Epilepsy in an Infant with a De Novo SCN2A Mutation.

Mutations in SCN2A genes have been described in patients with epilepsy, finding a large phenotypic variability, from benign familial epilepsy to epileptic encephalopathy. To explain this variability, it was proposed the existence of dominant modifier alleles at one or more loci that contribute to determine the severity of the epilepsy phenotype. One example of modifier factor may be the CACNA1G gene, as proved in animal models. We present a 6-day-old male newborn with recurrent seizures in which a mutation in the SCN2A gene is observed, in addition to a variant in CACNA1G gene. Our patient suffered in the first days of life myoclonic seizures, with pathologic intercritical electroencephalogram pattern, requiring multiple drugs to achieve adequate control of them. During the next weeks, the patient progressively improved until complete remission at the second month of life, being possible to withdraw the antiepileptic treatment. We propose that the variant in CACNA1G gene could have acted as a modifier of the epilepsy syndrome produced by the mutation in SCN2A gene in our patient.

[The new challenge in oncology: Next-generation sequencing and its application in precision medicine]. / El nuevo reto en oncología: la secuenciación NGS y su aplicación a la medicina de precisión.

Precision Medicine is an emerging approach for the diagnosis, treatment and prognosis of genetic diseases that enables clinicians to more accurately predict which treatment strategy will be optimal in a patient. The aim of Precision Medicine in Oncology is to integrate clinical, histological, and molecular data in order to obtain a deeper knowledge about the biology and genetics of an individual's tumour. Over the last few years, the implementation of new NGS (Next Generation Sequencing) technologies into clinical practice has been essential. There is a wide variety of NGS techniques that can be used in this context. The correct interpretation of molecular changes detected by these techniques is paramount for their appropriate use. In this review, a discussion is presented on the main NGS sequencing technologies that can be used to improve the diagnosis, prognosis, and treatment of oncology patients.

Study of USH1 splicing variants through minigenes and transcript analysis from nasal epithelial cells.

Usher syndrome type I (USH1) is an autosomal recessive disorder characterized by congenital profound deafness, vestibular areflexia and prepubertal retinitis pigmentosa. The first purpose of this study was to determine the pathologic nature of eighteen USH1 putative splicing variants found in our series and their effect in the splicing process by minigene assays. These variants were selected according to bioinformatic analysis. The second aim was to analyze the USH1 transcripts, obtained from nasal epithelial cells samples of our patients, in order to corroborate the observed effect of mutations by minigenes in patient's tissues. The last objective was to evaluate the nasal ciliary beat frequency in patients with USH1 and compare it with control subjects. In silico analysis were performed using four bioinformatic programs: NNSplice, Human Splicing Finder, NetGene2 and Spliceview. Afterward, minigenes based on the pSPL3 vector were used to investigate the implication of selected changes in the mRNA processing. To observe the effect of mutations in the patient's tissues, RNA was extracted from nasal epithelial cells and RT-PCR analyses were performed. Four MYO7A (c.470G>A, c.1342_1343delAG, c.5856G>A and c.3652G>A), three CDH23 (c.2289+1G>A, c.6049G>A and c.8722+1delG) and one PCDH15 (c.3717+2dupTT) variants were observed to affect the splicing process by minigene assays and/or transcripts analysis obtained from nasal cells. Based on our results, minigenes are a good approach to determine the implication of identified variants in the mRNA processing, and the analysis of RNA obtained from nasal epithelial cells is an alternative method to discriminate neutral Usher variants from those with a pathogenic effect on the splicing process. In addition, we could observe that the nasal ciliated epithelium of USH1 patients shows a lower ciliary beat frequency than control subjects.

Sequence variants of the DFNB31 gene among Usher syndrome patients of diverse origin.

PURPOSE: It has been demonstrated that mutations in deafness, autosomal recessive 31 (DFNB31), the gene encoding whirlin, is responsible for nonsyndromic hearing loss (NSHL; DFNB31) and Usher syndrome type II (USH2D). We screened DFNB31 in a large cohort of patients with different clinical subtypes of Usher syndrome (USH) to determine the prevalence of DFNB31 mutations among USH patients. METHODS: DFNB31 was screened in 149 USH2, 29 USH1, six atypical USH, and 11 unclassified USH patients from diverse ethnic backgrounds. Mutation detection was performed by direct sequencing of all coding exons. RESULTS: We identified 38 different variants among 195 patients. Most variants were clearly polymorphic, but at least two out of the 15 nonsynonymous variants (p.R350W and p.R882S) are predicted to impair whirlin structure and function, suggesting eventual pathogenicity. No putatively pathogenic mutation was found in the second allele of patients with these mutations. CONCLUSIONS: DFNB31 is not a major cause of USH.

Novel mutations in the USH1C gene in Usher syndrome patients.

PURPOSE: Usher syndrome type I (USH1) is an autosomal recessive disorder characterized by severe-profound sensorineural hearing loss, retinitis pigmentosa, and vestibular areflexia. To date, five USH1 genes have been identified. One of these genes is Usher syndrome 1C (USH1C), which encodes a protein, harmonin, containing PDZ domains. The aim of the present work was the mutation screening of the USH1C gene in a cohort of 33 Usher syndrome patients, to identify the genetic cause of the disease and to determine the relative involvement of this gene in USH1 pathogenesis in the Spanish population. METHODS: Thirty-three patients were screened for mutations in the USH1C gene by direct sequencing. Some had already been screened for mutations in the other known USH1 genes (myosin VIIA [MYO7A], cadherin-related 23 [CDH23], protocadherin-related 15 [PCDH15], and Usher syndrome 1G [USH1G]), but no mutation was found. RESULTS: Two novel mutations were found in the USH1C gene: a non-sense mutation (p.C224X) and a frame-shift mutation (p.D124TfsX7). These mutations were found in a homozygous state in two unrelated USH1 patients. CONCLUSIONS: In the present study, we detected two novel pathogenic mutations in the USH1C gene. Our results suggest that mutations in USH1C are responsible for 1.5% of USH1 disease in patients of Spanish origin (considering the total cohort of 65 Spanish USH1 patients since 2005), indicating that USH1C is a rare form of USH in this population.