Department of Clinical Genetics, Odense University Hospital, Odense, Denmark.
Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark.
Front Endocrinol (Lausanne). 2021 Jun 11;12:657873. doi: 10.3389/fendo.2021.657873. eCollection 2021.
Despite the enormous efforts to understand Congenital hyperinsulinism (CHI), up to 50% of the patients are genetically unexplained. We aimed to functionally characterize a novel candidate gene in CHI.
A 4-month-old boy presented severe hyperinsulinemic hypoglycemia. A routine CHI genetic panel was negative.
A trio-based whole-exome sequencing (WES) was performed. Gene knockout in the RIN-m cell line was established by CRISPR/Cas9. Gene expression was performed using real-time PCR.
Hyperinsulinemic hypoglycemia with diffuse beta-cell involvement was demonstrated in the patient, who was diazoxide-responsive. By WES, compound heterozygous variants were identified in the adenylyl cyclase 7, gene p.(Asp439Glu) and p.(Gly1045Arg). is calcium-sensitive, expressed in beta-cells and converts ATP to cAMP. The variants located in the cytoplasmic domains C1 and C2 in a highly conserved and functional amino acid region. RIN-m cells showed a significant increase in insulin secretion reaching 54% at low, and 49% at high glucose concentrations, compared to wild-type. In genetic expression analysis loss of function led to a 34.1-fold to 362.8-fold increase in mRNA levels of the insulin regulator genes and ( 0.0002), as well as increased glucose uptake and sensing indicated by higher mRNA levels of and upregulation of , and leading to the activation of the glucose stimulated-insulin secretion (GSIS) pathway.
This study identified a novel candidate gene, , to cause CHI activation of the GSIS pathway.
尽管人们在理解先天性高胰岛素血症（CHI）方面付出了巨大努力，但仍有多达 50%的患者的病因尚未得到明确的遗传学解释。我们旨在对 CHI 的一个新候选基因进行功能特征分析。
一名 4 个月大的男婴出现严重的高胰岛素血症性低血糖。常规的 CHI 基因谱检测结果为阴性。
进行了基于三亲的全外显子组测序（WES）。通过 CRISPR/Cas9 在 RIN-m 细胞系中建立基因敲除。使用实时 PCR 进行基因表达。
患者表现为弥漫性β细胞受累的高胰岛素血症性低血糖，对二氮嗪有反应。通过 WES，鉴定出腺苷酸环化酶 7 基因的复合杂合变体 p.(Asp439Glu)和 p.(Gly1045Arg)。该基因是钙敏感的，在β细胞中表达，将 ATP 转化为 cAMP。这些变体位于高度保守和功能的细胞质结构域 C1 和 C2 中。与野生型相比，RIN-m 细胞的胰岛素分泌显著增加，在低葡萄糖浓度下达到 54%，在高葡萄糖浓度下达到 49%。在基因表达分析中，功能丧失导致胰岛素调节基因 和 的 mRNA 水平增加了 34.1 倍至 362.8 倍（ 0.0002），以及葡萄糖摄取和感知增加，表现为 和 的 mRNA 水平升高， 和 的表达上调，导致葡萄糖刺激胰岛素分泌（GSIS）途径的激活。
本研究鉴定出一个新的候选基因 ，其导致 CHI 的发生，激活 GSIS 途径。
