MYH7基因Glu931del突变导致恶性肥厚型心肌病

目的 本研究拟查明1个中国汉族肥厚型心肌病（HCM）家系的致病突变,并探讨基因型-表型关联。方法 利用二代测序技术,全面筛查家系先证者的28个HCM相关致病基因。通过Sanger测序,在家系中验证和筛查发现的可能致病突变,并对突变携带者进行表型分析。结果 二代测序发现先证者携带MYH7基因Glu931del杂合突变。家系筛查发现4名患者均携带该突变,突变与疾病共分离,该突变为此HCM家系的致病突变,常染色体显性遗传。Glu931del突变位于MYH7基因第23外显子,三个核苷酸缺失（c.2791_2793del GAG）,导致其所编码的心脏β-肌球蛋白重链的第931位谷氨酸缺失。MYH7基因第931位谷氨酸残基在不同物种间高度保守。临床表型分析发现,家系中4例患者的左心室最厚厚度在19mm-30mm之间,静息状态均无明显左室流出道梗阻,表现为胸痛、心悸和呼吸困难,并伴黑曚或有晕厥史。该家系另有两例患者在家系筛查前发生猝死,确诊年龄分别为5岁和6岁,死亡年龄均为16岁。该家系随访12年,HCM临床症状进展较快,1例患者左心室最大厚度由7mm发展为30mm,两例患者心功能进展为NYHA分级Ⅲ/Ⅳ级。结论 MYH7基因Glu931del突变导致的HCM表型较严重,易发生猝死和心衰,但也存在较大的表型异质性。二代高通量测序可以用于HCM致病基因的全面筛查。     

Newly described recessive MYH11 disorder with clinical overlap of Multisystemic smooth muscle dysfunction and Megacystis microcolon hypoperistalsis syndromes

We describe a neonatal patient with fixed dilated pupils and pulmonary, bladder, and bowel dysfunction suspicious for the presence of ACTA2 R179 mediated multisystemic smooth muscle dysfunction syndrome. Whole exome sequencing revealed compound heterozygous mutations in MYH11 after ACTA2 specific testing revealed no abnormalities. The child lived until 18 months of age and represents the only reported case of an MYH11 compound heterozygote with widespread smooth muscle dysfunction.     

MYH9在人肝癌组织中的表达及其对肝细胞系增殖和凋亡的影响

目的探讨非肌肉肌球蛋白重链(MYH9)在肝癌组织中的表达及通过沉默MYH9基因对肝癌细胞系SMMC-7721的增殖及凋亡的影响。方法收集50组人肝癌组织及癌旁组织,选用人肝癌细胞系SMMC-7721和Hep G2及人正常肝细胞系LO2,免疫组织化学方法及Western blot检测肝癌组织及癌旁组织中MYH9蛋白的表达,Western blot检测SMMC-7721、Hep G2及LO2中MYH9蛋白的表达;将MYH9 siRNA转染SMMC-7721,CKK8法及流式细胞术检测沉默MYH9对肝癌细胞增殖及细胞凋亡的影响。结果 MYH9蛋白在肝癌组织中的表达明显高于癌旁(P0.05);MYH9蛋白在SMMC-7721及Hep G2中的表达均明显高于LO2(P0.05);沉默MYH9基因可抑制细胞增殖(P0.001),促进细胞凋亡(P0.05)。结论 MYH9蛋白在肝癌组织的表达显著高于癌旁组织;MYH9低表达能有效抑制肝癌细胞的增殖,促进其凋亡。     

中国人群肥厚型心肌病MYH7基因突变的研究与展望

肥厚型心肌病( hypertrophic cardiomyopathy, HCM)是一种以左心室或室间隔不对称性肥厚为基本特征的最常见遗传性心脏病,该病是青少年及年轻运动员猝死的最主要原因。先天基因缺陷是HCM主要的分子遗传学基础,其遗传方式遵循常染色体显性遗传模式。与HCM发病相关的基因较多,其中编码心脏β-肌球蛋白重链(cardiac beta-myosin heavy chain, MYH7)基因为HCM最主要的致病基因。通过查阅文献,检索到目前已报道的587例中国HCM患者被进行MYH7基因突变筛查,统计结果表明：共有150例中国HCM患者由MYH7基因外显子上的66个致病性突变所致。对已报道的中国HCM人群MYH7基因的突变特点进行总结和分析,这将为中国HCM人群的诊断、预防和治疗提供参考依据。     

Germline MUTYH (MYH) mutations in Portuguese individuals with multiple colorectal adenomas

Germinal mutations in the base excision repair (BER) gene MUTYH (MYH) have recently been described in association with predisposition to multiple colorectal adenomas and cancer. In contrast to the classic dominant condition of familial adenomatous polyposis (FAP) due to germinal mutations in the APC gene, the MYH polyposis is an autosomal recessive disease. The identification of individuals affected by MYH polyposis brings new and important implications for the diagnostic, screening, genetic counseling, follow up and therapeutic options in these patients. In this study, screening for germinal mutations in the MYH gene was performed in 53 Portuguese individuals with multiple colorectal adenomas or classic adenomatous polyposis, in whom no mutation had been identified in the APC gene. The results revealed the presence of biallelic germline MYH mutations in 21 patients. In addition, we here report 3 mutations (c.340T>C [p.Y114H]; c.503G>A [p.R168H]; and c.1186_1187insGG [p.E396fsX437]) which, to our knowledge, have not been previously described.     

Fechtner综合征肾脏病理特点及机制探讨

目的 研究Fechtner综合征先证者肾脏病改变特点并探讨其发病机制。 方法 采用HE染色、免疫组化、免疫荧光和电镜等方法对Fechtner综合征患者的肾活检组织进行研究。 结果 免疫组化结果显示在足细胞和远曲小管上皮，非肌性肌球蛋白重链IIA（NMMHC-IIA）有高表达，近曲小管刷状缘有微弱表达。与正常肾组织相比，患者NMMHC-IIA在硬化的肾小球足细胞的表达减少。免疫荧光结果提示患者肾小球有明显的NMMHC-IIA沉积；足细胞特异性抗体标记结果显示NMMHC-IIA主要沉积在患者的足细胞；电镜显示足突部分融合并伴微绒毛形成。 结论 突变的NMMHC-IIA沉积在肾小球足细胞，足突部分融合伴微绒毛形成影响了足细胞的功能,导致了Fechtner综合征肾脏病变的发生。     

Molecular basis and diagnostics of hereditary colorectal cancers

Hereditary colorectal cancer syndromes are classified according to the presence of unusually large number of adenomatous or hamartomatous polyps, or their absence. The latter category includes hereditary non‐polyposis colorectal cancer (Lynch syndrome) and its variants Muir‐Torre and Turcot's syndromes. Adenomatous polyposis syndromes include familial adenomatous polyposis (FAP) and its variants, and the recently identified MYH‐ (mutY homolog)‐associated polyposis. Hamartomatous polyposis syndromes include juvenile polyposis, Peutz‐Jeghers syndrome, and Cowden syndrome, which is now included within the broader category ‘PTEN (phosphatase and tensin homolog) hamartoma tumour syndrome’. Other syndromes such as the ‘hereditary breast and colon cancer’ and ‘familial colorectal cancer’ are not yet fully characterized. This review addresses the molecular basis of these syndromes with particular reference to the recent advances in this rapidly progressive field and the applications of such knowledge in diagnosis and management.     

Identification of six novel MYH9 mutations and genotype–phenotype relationships in autosomal dominant macrothrombocytopenia with leukocyte inclusions

The autosomal dominant macrothrombocytopenia with leukocyte inclusions, May-Hegglin anomaly (MHA), Sebastian syndrome (SBS), and Fechtner syndrome (FTNS), are rare platelet disorders characterized by a triad of giant platelets, thrombocytopenia, and characteristic Döhle body-like leukocyte inclusions. The locus for these disorders was previously mapped on chromosome 22q12.3–q13.2 and the disease gene was recently identified as MYH9, the gene encoding the nonmuscle myosin heavy chain-A. To elucidate the spectrum of MYH9 mutations responsible for the disorders and to investigate genotype–phenotype correlation, we examined MYH9 mutations in an additional 11 families and 3 sporadic patients with the disorders from Japan, Korea, and China. All 14 patients had heterozygous MYH9 mutations, including three known mutations and six novel mutations (three missense and three deletion mutations). Two cases had Alport manifestations including deafness, nephritis, and cataracts and had R1165C and E1841K mutations, respectively. However, taken together with three previous reports, including ours, the data do not show clear phenotype–genotype relationships. Thus, MHA, SBS, and FTNS appear to represent a class of allelic disorders with variable phenotypic diversity.