■非酒精性脂肪性肝病(NAFLD)是一种复杂的特征,估计全球患病率为25%。我们的目的是确定一个四代家族的遗传变异,进行性NAFLD导致肝硬化,代偿失调,在没有肥胖和2型糖尿病等常见危险因素的情况下,肝细胞癌的发展。
■使用外显子组测序和基因组比较来鉴定可能的因果变异。与健康非携带者和患有NAFLD的野生型患者相比,我们广泛表征了具有鉴定的新型变体的家庭成员的临床表型和餐后代谢反应。表达变体的肝细胞样细胞(HLC)来源于由纯合供体皮肤成纤维细胞产生的人诱导的多能干细胞,并使用CRISPR-Cas9恢复为野生型。使用成像评估表型,靶向RNA分析,和分子表达阵列。
■我们在MTTP中发现了一个罕见的因果变异c.1691T>Cp.I564T(rs745447480),编码微粒体甘油三酯转移蛋白(MTP),与进行性NAFLD相关,与代谢综合征无关,没有阿贝脂蛋白血症的特征性特征。来自纯合子供体的HLC具有显著低于野生型细胞的MTP活性和较低的脂蛋白ApoB分泌,同时具有相似的MTPmRNA和蛋白质水平。HLC中的细胞质甘油三酯积累引发内质网应激,分泌促炎介质,和产生活性氧。
■我们已经确定并表征了MTTP中罕见的因果变异,MTTPp.I564T的纯合性与进展性NAFLD相关,无任何其他阿贝脂蛋白血症表现。我们的研究结果为推动进行性NAFLD的机制提供了见解。
■MTTP基因中一种罕见的遗传变异已被鉴定为在没有典型疾病危险因素的四代家族中导致严重非酒精性脂肪肝疾病的发展。创建的带有这种变异基因的细胞系培养物的特征是了解这种遗传变异如何导致肝细胞缺陷。这导致脂肪的积累和促进疾病的过程。现在,这是研究疾病途径并发现治疗常见类型脂肪肝疾病的新方法的有用模型。
UNASSIGNED: Non-alcoholic fatty liver disease (NAFLD) is a complex trait with an estimated prevalence of 25% globally. We aimed to identify the genetic variant underlying a four-generation family with progressive NAFLD leading to cirrhosis, decompensation, and development of hepatocellular carcinoma in the absence of common risk factors such as obesity and type 2 diabetes.
UNASSIGNED: Exome sequencing and genome comparisons were used to identify the likely causal variant. We extensively characterised the clinical phenotype and post-prandial metabolic responses of family members with the identified novel variant in comparison with healthy non-carriers and wild-type patients with NAFLD. Variant-expressing hepatocyte-like cells (HLCs) were derived from human-induced pluripotent stem cells generated from homozygous donor skin fibroblasts and restored to wild-type using CRISPR-Cas9. The phenotype was assessed using imaging, targeted RNA analysis, and molecular expression arrays.
UNASSIGNED: We identified a rare causal variant c.1691T>C p.I564T (rs745447480) in MTTP, encoding microsomal triglyceride transfer protein (MTP), associated with progressive NAFLD, unrelated to metabolic syndrome and without characteristic features of
abetalipoproteinaemia. HLCs derived from a homozygote donor had significantly lower MTP activity and lower lipoprotein ApoB secretion than wild-type cells, while having similar levels of MTP mRNA and protein. Cytoplasmic triglyceride accumulation in HLCs triggered endoplasmic reticulum stress, secretion of pro-inflammatory mediators, and production of reactive oxygen species.
UNASSIGNED: We have identified and characterised a rare causal variant in MTTP, and homozygosity for MTTP p.I564T is associated with progressive NAFLD without any other manifestations of
abetalipoproteinaemia. Our findings provide insights into mechanisms driving progressive NAFLD.
UNASSIGNED: A rare genetic variant in the gene MTTP has been identified as responsible for the development of severe non-alcoholic fatty liver disease in a four-generation family with no typical disease risk factors. A cell line culture created harbouring this variant gene was characterised to understand how this genetic variation leads to a defect in liver cells, which results in accumulation of fat and processes that promote disease. This is now a useful model for studying the disease pathways and to discover new ways to treat common types of fatty liver disease.