It is a continuation of the project \"Genetic diabetes in Lithuania\" with the cohort of 1209 patients with diabetes. Prior screening for autoimmune markers confirmed type 1 diabetes (T1D) diagnosis in 88.1% (n=1065) of patients, and targeted next-generation sequencing identified 3.5% (n=42) pathogenic variants in MODY genes. Subsequently, 102 patients were classified as having diabetes of unknown etiology. 12/102 were found to have novel variants in potential diabetes genes (RFX2, RREB1, SLC5A1 (3 patients with variants in this gene), GCKR, MC4R, CASP10, TMPRSS6, HGFAC, DACH1, ZBED3). Co-segregation analysis and MMTT were carried out in order to study beta-cell function in subjects with specific variants.
MMTT analysis showed that probands with variants in MC4R, CASP10, TMPRSS6, HGFAC, and SLC5A1 (c.1415T>C) had sufficient residual beta-cell function with stimulated C-peptide (CP) >200 pmol/L. Seven individuals with variants in RFX2, RREB1, GCKR, DACH1, ZBED3 and SLC5A1 (c.1415T>C, and c.932A>T) presented with complete beta-cell failure. No statistical differences were found between patients with sufficient CP production and those with complete beta-cell failure when comparing age at the onset and duration of diabetes. Nineteen family members were included in co-segregation analysis; no diabetes cases were reported among them. Only in patient with the variant c.1894G>A in RFX2 gene, none of the family members were affected by proband\'s variant.
Functional beta-cell study in vivo allowed to select five most probable genes for monogenic diabetes. Familial co-segregation analysis showed that novel variant in RFX2 gene could be a possible cause of diabetes. Future functional analysis in vitro is necessary to support or rule out the genetic background as a cause of diabetes.
方法:这是“立陶宛遗传性糖尿病”项目的延续,该项目包括1209名糖尿病患者。在88.1%(n=1065)的患者中,自身免疫标志物的先前筛查证实了1型糖尿病(T1D)的诊断,靶向下一代测序在MODY基因中鉴定出3.5%(n=42)的致病变异。随后,102例患者被归类为病因不明的糖尿病。12/102被发现在潜在的糖尿病基因中具有新的变异(RFX2,RREB1,SLC5A1(3名患者在该基因中具有变异),GCKR,MC4R,CASP10,TMPRSS6,HGFAC,DACH1,ZBED3)。进行共分离分析和MMTT以研究具有特定变体的受试者中的β细胞功能。
结果:MMTT分析表明,在MC4R中具有变体的先证者,CASP10,TMPRSS6,HGFAC,SLC5A1(c.1415T>C)具有足够的残留β细胞功能,刺激的C肽(CP)>200pmol/L。7个个体在RFX2,RREB1,GCKR,DACH1,ZBED3和SLC5A1(c.1415T>C,和c.932A>T)表现为完全β细胞衰竭。当比较糖尿病发作时的年龄和持续时间时,在具有足够CP产生的患者和完全β细胞衰竭的患者之间没有发现统计学差异。共隔离分析包括19名家庭成员;其中没有糖尿病病例报告。仅在RFX2基因中变异c.1894G>A的患者中,没有一个家庭成员受到先证者变体的影响。
结论:体内功能β细胞研究允许选择五个最可能的单基因糖尿病基因。家族共分离分析表明,RFX2基因的新变异可能是糖尿病的一个可能原因。未来的体外功能分析是必要的,以支持或排除作为糖尿病原因的遗传背景。