Islet Dysregulation in Infants with Congenital Hyperinsulinism

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，他们的低血糖的治疗极其困难。最近的研究表明，HI与调节β细胞胰岛素分泌的途径中的遗传缺陷有关。虽然已经发现了9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病例和一半对二氮卓药物治疗有反应的病例。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，也涉及以前未识别的新遗传基因座。这项研究的长期目标是确定这些疾病中的基因-表型相关性，以指导诊断和治疗，并发现新形式的先天性高胰岛素血症。目的1将扩大对McQuarrie于1954年报道的具有重要历史意义的显性HI家系中高胰岛素血症的新基因座的研究。临床表型、连锁分析和下一代测序方法已确定HK1为可能的候选基因。这将通过招募更多的家系和功能分析来证实。目标2将扩大在我们的一大系列患有二氮卓反应性高胰岛素血症的儿童中寻找新候选基因缺陷的工作，这些儿童没有可识别的突变。我们将使用有针对性的下一代测序方法来识别已知基因座或新的额外基因座的合子后突变。目标3将继续努力确定对二氮卓无效并需要胰腺切除的儿童的分子缺陷的机制。我们将寻找11p上两个相邻基因的新的隐蔽或镶嵌突变，它们是导致这种形式的HI的大多数病例：ABCC8/SUR1和KCNJ11/Kir6.2。这将包括胰岛素释放的功能测试，以及对手术患者培养的胰岛进行分子分析，以确定合子后、马赛克突变、非编码区和MicroRNA位点的突变，或表观遗传甲基化缺陷。 相关性(请参阅说明)： 这项翻译研究项目旨在确定先天性高胰岛素血症(HI)的分子原因。将使用下一代DNA测序和先进的微观方法来寻找新的候选基因，以研究需要胰腺切除的儿童的胰岛。这一结果将改善对HI儿童的治疗，并为调节正常人的胰岛素分泌提供新的见解。

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 9 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. The long-term goals of the research are to identify genotype-phenotype correlations in these disorders to guide diagnosis and treatment and to uncover new forms of congenital hyperinsulinism. Aim 1 will extend and expand studies of the novel genetic locus for hyperinsulinism in the historically-important dominant HI family reported by McQuarrie in 1954. Clinical phenotyping, linkage analysis, and next-gen sequencing methods have identified HK1 as a likely candidate gene. This will be confirmed by recruitment of additional pedigrees and by functional assays. Aim 2 will extend the search for defects in novel candidate genes in our large series of children with diazoxide responsive hyperinsulinism that have no identifiable mutation. We will seek to identify either post-zygotic mutations of known loci or novel additional loci using targeted next-gen sequencing methods. Aim 3 will continue our efforts to define the mechanisms of molecular defects in children who fail to respond to diazoxide and require pancreatectomy. We will search for novel cryptic or mosaic mutations 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 functional testing of insulin release and molecular analysis of cultured islets from patients undergoing surgery to identify post-zygotic, mosaic mutations; mutations in non-coding regions, and microRNA sites; or epigenetic methylation defects. RELEVANCE (See instructions): This translational research project seeks to define the molecular causes of congenital hyperinsulinemic hypoglycemia (HI). Novel candidate genes will be sought using next-gen DNA sequencing and advanced micro-methods to study pancreatic islets from children requiring pancreatectomy. The results will improve the treatment of children with HI and provide new insight into regulation of insulin secretion in normal humans.