SAT292 Adrenal Insufficiency Associated With Biallelic Mutations In Porphyria Genes
SAT292 Adrenal Insufficiency Associated With Biallelic Mutations In Porphyria Genes
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DOI：
10.1210/jendso/bvad114.296
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发表时间：
2023-10-05
影响因子：
4.1
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披露：C.Smith：没有。答：杰克逊：没有。答：萨利希：没有。答：珍妮克：没有。E·斯泰钦：没有。D·达比：没有。L.格里芬：没有。S.Banka：没有。艾尔赛德：没有。陈丽君：没有。L·梅瑟雷尔：没有。肾上腺功能不全(AI)是危及生命的，可以单独出现，也可以合并其他共病。在这里，我们描述了一个AI与由原卟啉原氧化酶(PPOX)或同比例卟啉原氧化酶(CPOX)双等位基因突变引起的卟啉症相关的新家系。卟啉症是一组疾病，由血红素生物合成途径中的八种酶中的一种缺陷引起，分为急性卟啉症，主要导致神经内脏症状或皮肤卟啉症，主要影响皮肤。急性卟啉病发作可能危及生命，导致永久性残疾或死亡。杂色性卟啉病和遗传性同型卟啉病分别与PPOX和CPOX的常染色体显性突变相关，具有双等位基因遗传，罕见的报道和敲除的小鼠是胚胎的。我们对3个AI和杂色性或遗传性卟啉症家系进行了全外显组测序(WES)、阵列比较基因组杂交(ACGH)和全基因组测序(WGS)。在有4个患病个体的家系1中，Wes在痘中发现了纯合子突变p.Glu339Lys。ACGH和WGS在导致AI的基因中没有发现拷贝数变异(CNV)和其他变异，这在所有受影响的个体中都是常见的。在家系2和家系3中，WGS和WES分别检测到1例患者的CPOX p.(Pro367Ala)和2个兄弟姐妹的p.(Ser28Ter)的纯合突变，并有AI和遗传性同种异位症的临床表现。与其他急性卟啉病不同，杂合子双亲没有症状，既不表现出卟啉症，也不表现为AI，这表明酶功能水平对这两种表型都是关键。PPOX/CPOX活性降低可能通过以下任一途径导致AI：(1)缺乏促肾上腺皮质激素细胞色素P450酶活性的血红蛋白；(2)中间体卟啉的毒性或(3)氧化应激增加。为了研究其机制，我们首先建立了人肾上腺皮质细胞H295R，该细胞具有不同程度的ppox基因敲除(KD)。通过四甲基偶氮唑盐比色法或GFP积累法测定，72小时后ppox-KD细胞的增殖较低，线粒体呼吸减弱，可能是由于卟啉前体的毒性所致。在ppox-KD细胞中，Cyp11a1的表达无明显变化，而StAR和CYP17A1的表达显著降低。作为氧化应激标志的GSH/GSSG比值在KD细胞中较低，提示这些细胞中的ROS增加。最后，H295R细胞中至少60%的PPOX蛋白被敲除后，皮质醇的产量在基线时减少了2.2%(p<；0.01)，在Forsklin刺激的细胞中减少了1.9%(p<；0.0001)。类似的CPOX研究也在进行中。这些研究表明，带有双等位基因PPOX/CPOX突变的人皮质醇减少，结合以前的AI病例和途径中的其他基因，建议应该监测患有卟啉症的人的肾上腺功能。演示文稿：2023年6月17日星期六
Disclosure: C. Smith: None. A. Jackson: None. A. Al-Salihi: None. A. Janecke: None. E. Steichen: None. D. Darby: None. L. Griffin: None. S. Banka: None. S. Elsayed: None. L. Chan: None. L. Metherell: None. Adrenal insufficiency (AI) is life-threatening and can present alone or in combination with other co-morbidities. Here we describe families with a novel association of AI with porphyria caused by biallelic mutations in protoporphyrinogen oxidase (PPOX) or coproporphyrinogen oxidase (CPOX). The porphyrias are a group of disorders caused by defects in one of eight enzymes within the haem biosynthetic pathway, divided into acute porphyrias, resulting in mainly neurovisceral symptoms, or cutaneous porphyrias, mainly affecting the skin. Acute porphyria attacks can be life-threatening, resulting in permanent disability or death. Variegate porphyria and hereditary coproporphyria are associated with autosomal dominant mutations in PPOX and CPOX respectively, with biallelic inheritance rarely reported and knockout mice that are embryonic lethal.We performed whole exome sequencing (WES), array Comparative Genomic Hybridization (aCGH) and whole genome sequencing (WGS) in 3 families with AI and variegate or hereditary porphyria. In kindred 1, with 4 affected individuals, WES revealed a homozygous mutation, p.Glu339Lys, in PPOX. aCGH and WGS revealed no Copy Number Variants (CNVs) and no other variants, in genes causing AI, common to all affected individuals. In families 2 and 3, homozygous mutations in CPOX p.(Pro367Ala) in one patient and p.(Ser28Ter) in two siblings were identified by WGS and WES respectively, with a clinical picture of AI and hereditary coproporphyria. Unlike other acute porphyria kindreds, the heterozygous parents were asymptomatic, manifesting neither porphyria nor AI, suggesting that the level of enzyme function is key for both phenotypes.Reduced PPOX/CPOX activity could cause AI through either; (i) a dearth of haem for steroidogenic CYP450 enzyme action, (ii) toxicity of intermediate porphyrins or (iii) increased oxidative stress. To investigate the mechanism, we first created H295R, human adrenocortical cells, with differing degrees of PPOX-knockdown (KD) by shRNA. Proliferation, measured by MTT assay or GFP accumulation, was lower in PPOX-KD cells at 72 hours and mitochondrial respiration was diminished, possibly due to toxicity of porphyrin precursors. CYP11A1 expression was unaltered whereas STAR and CYP17A1 were significantly lower in PPOX-KD cells. GSH/GSSG ratio, a marker of oxidative stress, was lower in KD cells suggesting increased ROS in these cells. Finally, and definitively, knockdown of at least 60% PPOX protein in H295R cells reduced cortisol output by 2.2-fold (p<0.01) at baseline and 1.9-fold (p<0.0001) in forskolin stimulated cells. Similar CPOX studies are underway.These studies show that cortisol is reduced in individuals with biallelic PPOX/CPOX mutations and, in conjunction with previous cases of AI in association with other genes in the pathway, suggests adrenal function should be monitored in individuals with porphyria. Presentation: Saturday, June 17, 2023