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。心脏内肿瘤，包括心房粘液瘤，是中风和心力衰竭的重要原因，并可能表现为可遗传的全身疾病。Carney综合征是一种常染色体显性遗传性综合征，心内粘液瘤发生在皮肤色素沉着和雀斑样变以及较少见的心外粘液瘤和内分泌疾病的背景下。对遗传性疾病的研究，如卡尼复合体，对疾病病理生理学和正常生理学都有重要的见解。分子遗传学技术可用于研究受Carney复合体影响的家系，以确定该综合征的突变致病基因。我们的初步研究证实了这种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基因座，其几率为6万亿：1，包含至少四个家族的Carney复合病基因。在这一应用中，我们建议确定染色体17q上的Carney复合体疾病基因以及该基因中导致心脏粘液瘤的突变。新的微卫星和单倍型分析将用于完善17q卡尼复合体基因座(CAR)遗传图谱，并组装该地区的基因组克隆重叠群。此外，培养的粘液瘤细胞的杂合性丢失分析将被用来进一步减少包含CAR的遗传和物理间隔。将通过建立CAR基因座的YAC和其他大插入基因组克隆重叠群来执行该间隔的物理作图。已知的基因将通过基因组克隆重叠群的聚合酶链式反应和Southern杂交分析来确定它们是否映射到CAR基因座。CAR基因的新转录本将通过外显子捕获和cDNA选择研究来分离。然后，将对映射到该基因座的候选基因和转录本进行突变评估，以确定卡尼复合体疾病基因。对Carney复合体基因及其相关突变的结构分析将促进肿瘤转化机制的新概念，以及心脏和其他组织的正常生长动态平衡。提高对心脏细胞生长调控的了解将改善心脏粘液瘤的诊断和治疗，还将提出刺激心脏重塑的新方法，有助于肌病和缺血心脏的管理。

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.