Quantitative Analysis of Methylation Defects and Correlation With Clinical Characteristics in Patients With Pseudohypoparathyroidism Type I and GNAS Epigenetic Alterations
Quantitative Analysis of Methylation Defects and Correlation With Clinical Characteristics in Patients With Pseudohypoparathyroidism Type I and GNAS Epigenetic Alterations
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DOI：
10.1210/jc.2013-3086
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发表时间：
2014-03-01
影响因子：
5.8
通讯作者：
Mantovani, Giovanna
中科院分区：
文献类型：
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作者：
Elli, Francesca M.;de Sanctis, Luisa;Mantovani, Giovanna
背景：假甲状旁腺功能减退I型（PHP-I）包括两个主要亚型，PHP-Ia和-Ib。大约70%的PHP-Ia患者表现出与多种激素（PTH/TSH/GHRH/促性腺激素）耐药相关的Albright遗传性骨营养不良（ho），在刺激G蛋白（Gs α）外显子1-13的α亚基携带杂合突变，该亚基由鸟嘌呤核苷酸结合蛋白α刺激活性多肽1 （GNAS）编码，而大多数典型表现为激素耐药的PHP-Ib患者仅局限于PTH和TSH，没有ho征象。在印迹的GNAS簇中有甲基化缺陷。最近，在PHP和不同程度的who患者中也发现了甲基化缺陷，这表明两种形式之间存在分子重叠。目的：本研究的目的是收集具有以下特征的患者：临床PHP-I（伴有或不伴有who）， Gs α编码序列无突变，但存在GNAS甲基化改变，并研究表观遗传缺陷程度与疾病严重程度之间是否存在相关性。患者和方法：我们通过pcr -焦磷酸测序和甲基化特异性多重连接依赖探针扩增法对63例PHP-I患者的基因组DNA进行了GNAS甲基化改变的量化，并将这些发现与临床参数（诊断年龄；钙、磷、甲状旁腺激素、促甲状腺激素水平；存在或不存在每种who体征）相关联。结果：通过这两种方法，印迹缺陷的程度与疾病的发病、内分泌抵抗的严重程度或是否存在特定的who体征无关。结论：类似的分子改变可能导致广泛的疾病，从分离的PTH抗性到完全的PHP- ia，甲基化改变的程度不能反映或预测不同PHP/ who表现的严重程度和类型。
Context: Pseudohypoparathyroidism type I (PHP-I) includes two main subtypes, PHP-Ia and -Ib. About 70% of PHP-Ia patients, who show Albright hereditary osteodystrophy (AHO) associated with resistance toward multiple hormones (PTH/TSH/GHRH/gonadotropins), carry heterozygous mutations in the alpha-subunit of the stimulatory G protein (Gs alpha) exons 1-13, encoded by the guanine nucleotide binding-protein alpha-stimulating activity polypeptide 1 (GNAS), whereas the majority of PHP-Ib patients, who classically display hormone resistance limited to PTH and TSH with no AHO sign, have methylation defects in the imprinted GNAS cluster. Recently methylation defects have been detected also in patients with PHP and different degrees of AHO, indicating a molecular overlap between the two forms.Objectives: The objectives of the study were to collect patients with the following characteristics: clinical PHP-I (with or without AHO), no mutation in Gs alpha coding sequence, but the presence of GNAS methylation alterations and to investigate the existence of correlations between the degree of the epigenetic defect and the severity of the disease.Patients and Methods: We quantified GNAS methylation alterations by both PCR-pyrosequencing and methylation specific-multiplex ligation-dependent probe amplification assay in genomic DNA from 63 patients with PHP-I and correlated these findings with clinical parameters (age at diagnosis; calcium, phosphorus, PTH, TSH levels; presence or absence of each AHO sign).Results: By both approaches, the degree of the imprinting defect did not correlate with the onset of the disease, the severity of endocrine resistances, or with the presence/absence of specific AHO signs.Conclusions: Similar molecular alterations may lead to a broad spectrum of diseases, from isolated PTH resistance to complete PHP-Ia, and the degree of methylation alterations does not reflect or anticipate the severity and the type of different PHP/AHO manifestations.