GENETIC BASIS OF CLEFT LIP AND PALATE

描述(申请人提供)：这项拟议研究的长期目标是了解颅面发育和口裂发病的分子遗传学机制。口腔裂，包括唇裂和腭裂，是一种常见的出生缺陷，全世界大约每700名活产儿中就有1名受到影响。患有面部裂隙的人要接受广泛的外科、牙科、言语和心理治疗，这些治疗通常从婴儿期到十几岁持续很多年。尽管这类出生缺陷经常发生，并与大量昂贵的医疗治疗有关，但导致唇裂和/或腭裂的原因和致病过程尚不清楚。最近在动物模型系统中的研究表明，脸部的发育，就像其他器官的发育一样，在很大程度上受到遗传因素的控制。事实上，有越来越多的证据表明，特定的基因突变与口裂有关。我们最近发现了一种名为twirler的自发突变，它会导致纯合子突变小鼠的唇裂和腭裂，与Zfhx1a基因的变化有关。有趣的是，Zfhx1a基因的功能是正常头面部发育所必需的，因为该基因的靶向破坏导致了小鼠的头面部缺陷，包括腭裂。Zfhx1a基因在进化上是保守的，人类同源基因的突变会导致多种发育缺陷。此外，Zfhx1a基因产物已被证明与BMP和转化生长因子-β信号相互作用并进行调节，这是调节正常颅面发育的主要分子途径，并参与了小鼠和人类唇腭裂的发病。因此，我们建议确定确切的遗传损伤和面部裂隙形成的发育机制。我们还将确定Twirler/Zfhx1a在颅面发育过程中与BMP/转化生长因子-β信号通路的遗传相互作用。这些研究将极大地提高我们对口腔裂隙形成的致病机制的了解，并将导致更好地诊断、治疗和/或预防口面部裂隙的方法的发展。

DESCRIPTION (provided by applicant): The long-term goal of this proposed research is to understand the molecular genetic mechanisms of craniofacial development and of orofacial cleft pathogenesis. Orofacial clefts, including cleft lip and cleft palate, are common birth defects that affect approximately 1 in 700 live births worldwide. Individuals with facial clefts undergo extensive surgical, dental, speech and psychological therapies that usually last for many years from infancy through the teenage years. Despite the frequent occurrence and extensive costly medical treatments associated with such birth defects, the causes and the pathogenic processes that lead to cleft lip and/or cleft palate are not well understood. Recent studies in animal model systems showed that development of the face, like development of other organs, are largely controlled by genetic factors. Indeed, there is accumulating evidence that specific gene mutations are associated with orofacial clefting. We have recently found that a spontaneous mutation, named Twirler, that causes cleft lip with cleft palate in homozygous mutant mice, is associated with alteration of the Zfhx1a gene. Interestingly, the Zfhx1a gene function is required for normal craniofacial development because a targeted disruption in this gene caused craniofacial defects including cleft palate in mice. The Zfhx1a gene is evolutionarily conserved and mutations in the human homolog causes multiple developmental defects. Moreover, the Zfhx1a gene product has been shown to interact with and regulate Bmp and Tgf-beta signaling, major molecular pathways regulating normal craniofacial development and involved in cleft lip/palate pathogenesis in mice and humans. Thus, we propose to determine the exact genetic lesion and the developmental mechanisms underlying facial cleft formation in the Twirler mutant mice. We will also determine the genetic interactions of Twirler/Zfhx1a with the Bmp/Tgf- beta signaling pathways during craniofacial development. These studies will greatly increase our understanding of the pathogenic mechanisms underlying orofacial cleft formation and will lead to development of methods for better diagnosis, treatment and/or prevention of orofacial clefting.