Islet Dysregulation in Infants with Congenital Hyperinsulinism

项目摘要 先天性高胰岛素血症(HI)是婴幼儿持续性低血糖最常见的原因。 患有HI的儿童癫痫发作和永久性脑损伤的风险很高，并有低血糖的治疗 是非常困难的。最近的研究表明，HI与通路中的遗传缺陷有关 调节胰岛细胞胰岛素的分泌。虽然已经发现了6个这样的基因座，但许多HI儿童没有 这些基因的可识别突变。这包括三分之一需要胰腺切除的弥漫性HI病例。 对二氮卓药物治疗有反应的病例有一半。我们的假设是 这些儿童的高胰岛素血症既涉及已知基因座的新分子缺陷，也涉及 以前未被识别的新遗传位点。我们的长期目标是确定基因和表型之间的相关性 这些疾病指导诊断和治疗，并发现新的形式的先天性高胰岛素血症。目标 1将在McQuarrie报告的具有历史意义的显性HI家族中鉴定新的遗传基因座 1954年。初步数据已将这种形式的HI定位于染色体10q上的8.4mb区域，该区域包括 高亲和力己糖激酶HK1。受影响家庭成员的胰岛功能失调的表型将是 通过对胰岛素分泌的临床研究来定义。连锁分析和新获得的基因捕获和高效率 将使用吞吐量测序方法来鉴定导致这一新的疾病的突变 HI的形式。目标2将在我们的一大群患有二氮卓的儿童中寻找新的候选基因的缺陷- 无可识别突变的反应性高胰岛素血症。外周血基因组的突变分析 DNA将被用来检测潜在的候选基因，包括将被识别的10q上的新基因 在目标1中，HADH/SCHAD、SLC16A1/MCT-1、TCF1/HNF1、TCF4/HNF4、SIR2L4/SIRT4等。目标3 将确定对二氮卓无效并需要治疗的儿童分子缺陷的机制 胰腺切除手术。我们将寻找11P上两个相邻基因的新的分子缺陷 对大多数这种形式的HI负责：ABCC8/SUR1和KCNJ11/Kir6.2。这将包括突变 使用高通量测序对这些基因的全部120kb区域进行分析；分析胰腺 合子后马赛克突变的遗传和组织学证据的组织.启动子突变的测试 区域、3‘非编码区和microRNA位点；以及筛查表观遗传甲基化缺陷。

Project Summary Congenital hyperinsulinism (HI) is the most frequent cause of persistent hypoglycemia in infants and children. Children with HI are at high risk of seizures and permanent brain damage and treatment of their hypoglycemia is extremely difficult. Recent work has shown that HI is associated with genetic defects in the pathways regulating beta-cell insulin secretion. Although 6 such loci have been found, many children with HI have no identifiable mutation of these genes. This includes one-third of diffuse HI cases that require pancreatectomy and half of cases that are responsive to medical treatment with diazoxide. Our hypothesis is that hyperinsulinism in these groups of children involves both novel molecular defects of known loci, as well as, previously unrecognized new genetic loci. Our long-term goal is to identify genotype-phenotype correlations in these disorders to guide diagnosis and treatment and to uncover new forms of congenital hyperinsulinism. Aim 1 will identify the novel genetic locus in the historically-important dominant HI family reported by McQuarrie in 1954. Preliminary data have mapped this form of HI to an 8.4 mb region on chromosome 10q that includes the high affinity hexokinase enzyme, HK1. The phenotype of islet dysregulation in affected family members will be defined by clinical studies of insulin secretion. Linkage analysis and newly-available gene capture and high- throughput sequencing methods will be used to identify the disease-causing mutation responsible for this novel form of HI. Aim 2 will search for defects in novel candidate genes in our large group of children with diazoxide- responsive hyperinsulinism that have no identifiable mutation. Mutation analysis of peripheral blood genomic DNA will be used to examine potential candidate genes, including the novel gene on 10q that will be identified in Aim 1, HADH/SCHAD, SLC16A1/MCT-1, TCF1/HNF1, TCF4/HNF4, SIR2L4/SIRT4, and others. Aim 3 will define the mechanisms of molecular defects in children who fail to respond to diazoxide and require pancreatectomy. We will search for novel molecular defects of the two adjacent genes on 11p that are responsible for most cases of this form of HI: ABCC8/SUR1 and KCNJ11/Kir6.2. This will include mutation analysis of the entire 120 kb region of these genes using high-throughput sequencing; analyzing pancreatic tissue for genetic and histological evidence of post-zygotic, mosaic mutations; testing for mutations in promoter regions, 3'UTR regions, and microRNA sites; and screening for epigenetic methylation defects.