SINGLE SUTURE CRANIOSYNOSTOSIS: CANDIDATE GENE AND PATHWAY DISCOVERY

描述（由申请方提供）：颅缝早闭是颅骨缝的病理性融合。它与显著的发病率、偶尔的死亡率相关，并带来相当大的经济负担。使用候选基因重测序和比较基因组杂交的组合，TWIST 1功能丧失突变和IGF 1 R和RUNX 2功能获得突变已被确定。结合网络建模的表达阵列分析已经确定IGF 1-RUNX 2通路的激活是大亚组病例中颅缝早闭的潜在原因。基于生物学的亚组的鉴定是理解骨性结合病因的关键进展，因为它提供了将研究工作集中在表型相似的病例队列上的能力。这种竞争性的更新提出了使用基因组学，网络建模，动物模型和新的细胞生物学方法来揭示遗传和发育途径，当中断时，导致过早的颅骨融合。新的（Igf 1 rGOF）和现有的（Igf 1GOF，Gsk 3bLOF，Twist 1 LOF）小鼠资源将用于模拟这种疾病的多基因遗传。通过跨学科的研究工作，三个独立但高度集成的目标将测试假设，即孤立的单缝颅缝早闭儿童的子集具有可识别的遗传变异，导致增强的颅骨成骨细胞分化，IGF 1-RUNX 2通路的激活。特定目标1将鉴定成骨细胞细胞表型的变化，证明IGF 1-RUNX 2通路的激活。我们将利用成骨细胞生长和分化的措施，以及细胞生物力学的措施，以完善我们的原始队列的生物表型。具体目标2将开发和表征人IGF 1 RR 406 H功能获得性突变的诱导型Igf 1 rR 407 H小鼠模型。11我们将使用现有突变小鼠资源（Igf 1GOF、Gsk 3bLOF、Twist 1 LOF）繁殖和表型Igf 1 rR 407 H复合杂合小鼠，以开发人类SSC多基因遗传模型。具体目标3将确定IGF 1/RUNX 2亚组病例中基因组变异在颅缝早闭发生中的作用。我们将使用来自原始队列（N=211）的转录组序列数据和来自IGF 1/RUNX 2亚组病例（N=48）的全基因组序列数据来完善途径并确定基因表达改变、编码变体和调控区变异之间的相关性。我们将招募一个新的SSC队列，以验证所识别的转录组和基因组变异。孤立性颅缝早闭症的诊断和治疗存在重大差距，包括缺乏分子诊断检测、适当的家庭咨询和生物治疗以降低患者发病率。目前对颅缝早闭的病因还不完全了解，我们缺乏实验模型。这些资源的开发将改善临床护理，设计基于生物学的治疗方法，并进行初级预防。

DESCRIPTION (provided by applicant): Craniosynostosis is the pathologic fusion of the sutures of the calvaria. It is associated with significant morbidity, occasional mortality, and carries a considerable financial burden. Using a combination of candidate gene resequencing and comparative genome hybridization TWIST1 loss-of-function mutations and IGF1R and RUNX2 gain-of-function mutations have been identified. Expression array analysis coupled with network modeling has identified activation of an IGF1-RUNX2 pathway as a potential cause of craniosynostosis in a large subgroup of cases. The identification of a biologically based subgroup is a critical advance toward understanding the cause of synostosis as it affords an ability to focus research efforts on a phenotypically similar cohort of cases. This competitive renewal proposes the use of genomics, network modeling, animal models and novel cell biologic approaches to reveal genetic and developmental pathways which, when disrupted, result in premature calvarial fusion. New (Igf1rGOF) and existing (Igf1GOF, Gsk3bLOF, Twist1LOF) mouse resources will be used to model the polygenic inheritance of this disorder. Through interdisciplinary research efforts, three independent yet highly integrated aims will test the hypothesis that a subset of children with isolated single suture craniosynostosis has identifiable genetic variation that results in enhanced calvarial osteoblast differentiation throug activation of an IGF1-RUNX2 pathway. Specific Aim 1 will identify changes in the cellular phenotype of osteoblasts demonstrating activation of the IGF1-RUNX2 pathway. We will utilize measures of osteoblast growth and differentiation as well as measures of cellular biomechanics to refine the biologic phenotype of our original cohort. Specific Aim 2 will develop and characterize an inducible Igf1rR407H mouse model of the human IGF1RR406H gain-of-function mutation.11 We will breed and phenotype Igf1rR407H compound heterozygous mice using existing mutant mouse resources (Igf1GOF, Gsk3bLOF, Twist1LOF) to develop models for the polygenic inheritance of SSC in humans. Specific Aim 3 will determine the contribution of genomic variation in the development of craniosynostosis among cases in the IGF1/RUNX2 subgroup. We will use transcriptome sequence data from the original cohort (N=211) and whole genome sequence data from the IGF1/RUNX2 subgroup cases (N=48) to refine the pathway and identify correlates between alteration in gene expression, coding variants and regulatory region variation. We will recruit a new SSC cohort to validate the transcriptomic and genomic variation identified. Major gaps exist in the diagnosis and management of isolated craniosynostosis including the lack of molecular diagnostic testing, adequate family counseling, and biologic therapies to reduce patient morbidity. There is an incomplete understanding of the causes of craniosynostosis and we lack experimental models. The development of these resources will improve clinical care, design biologically based therapies, and pursue primary prevention.