MOLECULAR GENETICS OF CARDIAC MYXOMAS (CARNEY COMPLEX)

心血管疾病往往是多系统疾病的主要异常。心内肿瘤，包括心房黏液瘤，是中风和心力衰竭的重要原因，可能表现为遗传性全身性疾病。卡尼复合体是一种常染色体显性综合征，心内黏液瘤出现在皮肤色素沉着和小透镜体病的背景下，以及不太常见的心外黏液瘤和内分泌病。对遗传疾病的研究，如卡尼复合体，对疾病病理生理学和正常生理学产生了重要的见解。分子遗传学技术可用于研究受卡尼复合体影响的种类，以确定该综合征中突变的疾病基因。我们的初步调查显示了该综合征的遗传异质性，现在已经在17号染色体长臂上定义了一个新的13 cM位点，其几率为6万亿：1，至少在四个家庭中包含卡尼复杂疾病基因。在本申请中，我们拟鉴定染色体17q上的卡尼复合体病基因以及该基因引起心内黏液瘤的突变。新的微卫星和单倍型分析将用于完善17q卡尼复杂位点（CAR）遗传图谱，并组装该区域的基因组克隆群。此外，对培养的黏液瘤细胞进行失杂合度分析，进一步减少含有CAR的遗传和物理间隔。将通过建立CAR位点的YAC和其他大插入基因组克隆组群来进行间隔的物理定位。已知基因将通过PCR和基因组克隆组群的southern blot分析来确定它们是否映射到CAR位点。CAR位点的新转录本将通过外显子捕获和cDNA选择研究分离出来。候选基因和转录本映射到这个位点，然后评估突变，以确定卡尼复杂病基因。对卡尼复合体基因及其相关突变的结构分析将为肿瘤转化机制以及心脏和其他组织的正常生长稳态提供新的概念。加深对心肌细胞生长调节的了解将改善心内黏液瘤的诊断和治疗，并将提出刺激心脏重塑的新方法，有助于肌病和缺血性心脏的治疗。

Cardiovascular disorders often are the primary abnormalities in multisystem disease. Intracardiac tumors, including atrial myxomas, are significant causes of stroke and heart failure and may present as heritable systemic disorders. The Carney complex is an autosomal dominant syndrome in which intracardiac myxomas, arise in the setting of cutaneous hyperpigmentaton and lentiginosis along with less common extracardiac myxomas as well as endocrinopathy. Investigation of genetic diseases, such as Carney complex, yields important insights into disease pathophysiology as well as normal physiology. Molecular genetic techniques can be used to study kindreds affected by Carney complex in order to identify the mutated disease gene in this syndrome. Our preliminary investigation demonstrated genetic heterogeneity of this syndrome and now has defined a novel 13 cM locus on the long arm of chromosome 17 that, with odds of 6 trillion: 1, contains the Carney complex disease gene in at least four families. In this application, we propose to identify the Carney complex disease gene on chromosome 17q and the mutations in this gene that cause intracardiac myxomas. New microsatellites and haplotype analysis will be used to refine the l7q Carney complex locus (CAR) genetic map and to assemble a genomic clone contig of the region. In addition, loss of heterozygosity analysis of cultured myxoma tumor cells will be employed to reduce further the genetic and physical interval containing CAR. Physical mapping of the interval will be performed by establishing YAC and other large insert genomic clone contigs of the CAR locus. Known genes will be assayed to determine if they map to the CAR locus by PCR and southern blot analysis of the genomic clone contigs. Novel transcripts at the CAR locus will be isolated by exon trapping and cDNA selection studies. Candidate genes and transcripts that do map to this locus will then be evaluated for mutations to identify the Carney complex disease gene. Structural analysis of the Carney complex gene and its associated mutations will foster new concepts of mechanisms underlying neoplastic transformation as well as normal growth homeostasis in the heart and other tissues. Increased understanding of the regulation of cardiac cell growth will improve diagnosis and treatment of intracardiac myxomas and will also suggest novel approaches to stimulate cardiac remodeling that can contribute to the management of the myopathic and ischemic heart.