Whole-Genome Analysis in Korean Patients with Autoimmune Myasthenia Gravis

PURPOSE: The underlying cause of myasthenia gravis (MG) is unknown, although it likely involves a genetic component. However, no common genetic variants have been unequivocally linked to autoimmune MG. We sought to identify the genetic variants associated with an increased or decreased risk of developing MG in samples from a Korean Multicenter MG Cohort. MATERIALS AND METHODS: To determine new genetic targets related to autoimmune MG, a whole genome-based single nucleotide polymorphisms (SNP) analysis was conducted using an Axiom(TM) Genome-Wide ASI 1 Array, comprising 598375 SNPs and samples from 109 MG patients and 150 neurologically normal controls. RESULTS: In total, 641 SNPs from five case-control associations showed p-values of less than 10(-5). From regional analysis, we selected seven candidate genes (RYR3, CACNA1S, SLAMF1, SOX5, FHOD3, GABRB1, and SACS) for further analysis. CONCLUSION: The present study suggests that a few genetic polymorphisms, such as in RYR3, CACNA1S, and SLAMF1, might be related to autoimmune MG. Our findings also encourage further studies, particularly confirmatory studies with larger samples, to validate and analyze the association between these SNPs and autoimmune MG.

Mutation status of gene CACNA1S and SCN4A in the hypokalemic periodic paralysis pedigree in Chinese population / 解放军医学杂志

Objective To investigate the mutation status of gene CACNA1S and SCN4A in hypokalemic periodic paralysis (HPP) pedigree of Chinese population, and compare the status with that in Caucasian populations as reported in previous literature. Methods To define the gene mutation status, the genes CACNA1S and SCN4A were sequenced by PCR and DNA sequencing technology in two familial HPP pedigrees, one hyperthyroid HPP pedigree and four sporadic HPP patients, the findings were then compared with the reference sequences in gene library. A total of nine relevant reports concerning the gene CACNA1S and SCN4A mutation of HPP pedigree published from Jan. 1999 to Dec. 2012 were retrieved from PubMed database. Results All the probands were suffering from paroxysmal muscle weakness with hypokalemia. As a typical symptom of HPP, muscle weakness often involved the extremities. Auxiliary examination confirmed serum hypopotassemia, electrocardiogram (ECG) showed hypokalemic change, and electromyography (EMG) showed shortened motor potential duration and low amplitude. All the findings mentioned above were in accordance with clinical diagnosis of HPP. Gene analysis indicated that no mutation of CACNA1S and SCN4A was found in the probands, the family members of the three HPP pedigrees and the four patients of sporadic HPP. The previous literature presented that mutation rate of gene CACN1AS and SCN4A was much higher in Caucasian HPP patients than in Chinese population. Conclusion The mutation rate of gene CACN1AS and SCN4A is lower in Chinese HPP patients than in Caucasian patients with significant difference.

Hypokalemic periodic paralysis; two different genes responsible for similar clinical manifestations / 소아과

Primary hypokalemic periodic paralysis (HOKPP) is an autosomal dominant disorder manifesting as recurrent periodic flaccid paralysis and concomitant hypokalemia. HOKPP is divided into type 1 and type 2 based on the causative gene. Although 2 different ion channels have been identified as the molecular genetic cause of HOKPP, the clinical manifestations between the 2 groups are similar. We report the cases of 2 patients with HOKPP who both presented with typical clinical manifestations, but with mutations in 2 different genes (CACNA1Sp.Arg528His and SCN4A p.Arg672His). Despite the similar clinical manifestations, there were differences in the response to acetazolamide treatment between certain genotypes of SCN4A mutations and CACNA1S mutations. We identified p.Arg672His in the SCN4A gene of patient 2 immediately after the first attack through a molecular genetic testing strategy. Molecular genetic diagnosis is important for genetic counseling and selecting preventive treatment.

Hypokalemic periodic paralysis; two different genes responsible for similar clinical manifestations / 소아과

Primary hypokalemic periodic paralysis (HOKPP) is an autosomal dominant disorder manifesting as recurrent periodic flaccid paralysis and concomitant hypokalemia. HOKPP is divided into type 1 and type 2 based on the causative gene. Although 2 different ion channels have been identified as the molecular genetic cause of HOKPP, the clinical manifestations between the 2 groups are similar. We report the cases of 2 patients with HOKPP who both presented with typical clinical manifestations, but with mutations in 2 different genes (CACNA1Sp.Arg528His and SCN4A p.Arg672His). Despite the similar clinical manifestations, there were differences in the response to acetazolamide treatment between certain genotypes of SCN4A mutations and CACNA1S mutations. We identified p.Arg672His in the SCN4A gene of patient 2 immediately after the first attack through a molecular genetic testing strategy. Molecular genetic diagnosis is important for genetic counseling and selecting preventive treatment.