Analysis of genetic linkage in malignant hyperthermia susceptible families in Japan

通过使用RYR 1基因多态性的连锁分析，我们调查了RYR 1异常的遗传证据与骨骼肌肌浆网钙诱导钙释放（CICR）机制的加速率之间的关系，从恶性高热易感（MHS）的主题和家庭在日本。在72例转介到我所进一步调查MHS的受试者中，26例受试者接受了骨骼肌活检，以皮肤纤维法测量CICR率。通过采集静脉血，还从这26个无关家庭的受试者中获得了DNA样本。应用限制性片段长度多态性（RFLP）分析RYR 1基因座和高变微卫星，对4例临床表现为暴发性恶性高热（MH）患者及其3名亲属的CICR率进行了研究。在72例受试者中进行了C1840 T替代分析，但未证明发生变化。但是，我们可以确定一个家庭为MHS，因为信息多态性提示CICR率的加速与RYR 1基因之间的连锁。在该家系中，RYR 1基因的连锁研究将有助于MHS的进一步研究，如果能确定MH的异质性与CICR率增高之间的关系，我们认为基因检测可取代CICR检测作为MH的诊断工具（1/74，000例全身麻醉）和少数MHS受试者可能接受侵入性肌肉活检，我们得出结论，有必要改进遗传学检测，并确定日本MH调查的关系。

By using linkage-analysis of RYR1 gene polymorphism, we investigated the relation between genetic evidence of RYR1 abnormalities and accelerated rate of Ca-induced Ca release (CICR) mechanism of sarcoplasmic reticulum in skeletal muscle from malignant hyperthermia susceptible (MHS) subjects and families in Japan. Of 72 subjects referred to our institute for further investigation of MHS,26 subjects received skeletal muscle biopsy for the measurement of CICR rate by the skinned fiber method. By sampling venous blood, DNA samples were also obtained from the subjects in these 26 unrelated families. Analyzes of restriction fragment length polymorphism (RFLP) on RYR1 locus and hypervariable microsatellite were performed to investigate the relation between RYR1 abnormalities and acceleration of CICR rate.Accelerated CICR rate was observed in 4 subjects who presented clinically fulminant malignant hyperthemia (MH) and in their 3 relatives. Analysis for substitution of C1840T was performed in 72 subjects, while no alteration was demonstrated. However, we could determine one family as MHS because informative polymorphism suggested the linkage between the acceleration of CICR rate and RYR1 gene. In this family, the linkage study of RYR1 gene would be useful for further investigation of MHS.If the relation is determined between heterogeneity of MH and acceleration of CICR rate, we believe that the genetic test could replace the CICR test as a diagnostic tool for MH.Because occurrence of MH is rare (1 of 74,000 general anesthesias) and a few of MHS subjects may receive the invasive muscle biopsy, we conclude that it is necessary to improve the genetic test and to determine the relation for the investigation of MH in Japan.