Schipani E, Langman C B, Parfitt A M, Jensen G S, Kikuchi S, Kooh S W, Cole W G, Jüppner H
Department of Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
N Engl J Med. 1996 Sep 5;335(10):708-14. doi: 10.1056/NEJM199609053351004.
An activating mutation of the receptor for parathyroid hormone (PTH) and parathyroid hormone-related peptide (PTHrP) was recently found in a patient with Jansens's metaphyseal chondrodysplasia, a rare form of short-limbed dwarfism associated with hypercalcemia and normal or low serum concentrations of the two hormones. To investigate this and other activating mutations and to refine the classification of this unusual disorder, we analyzed genomic DNA from six additional patients with Jansen's disease.
Exons encoding the PTH-PTHrP receptor were amplified by the polymerase chain reaction (PCR), and the products were analyzed by gel electrophoresis or direct nucleotide-sequence analysis. Nucleotide changes were confirmed by restriction-enzyme digestion of genomic DNA or the PCR products.
The previously reported mutation, which changes a histidine at position 223 to arginine (H223R), was found in genomic DNA from three of the six patients but not in DNA from their healthy relatives or 45 unrelated normal subjects. A novel missense mutation that changes a threonine in the receptor's sixth membrane-spanning region to proline (T410P) was identified in another patient but not in 62 normal subjects. In two patients with radiologic evidence of Jansen's metaphyseal chondrodysplasia but less severe hypercalcemia, no receptor mutations were detected. In COS-7 cels expressing PTH-PTHrP receptors with the T410P or H223R mutation, basal cyclic AMP accumulation was four to six times higher than in cells expressing wild-type receptors.
The expression of constitutively active PTH-PTHrp receptors in kidney, bone, and growth-plate chondrocytes provides a plausible genetic explanation for mineral-ion abnormalities and metaphyseal changes in patients with Jansen's disease.
最近在一名患有詹森干骺端软骨发育不良的患者中发现了甲状旁腺激素（PTH）和甲状旁腺激素相关肽（PTHrP）受体的激活突变。詹森干骺端软骨发育不良是一种罕见的短肢侏儒症，与高钙血症相关，且这两种激素的血清浓度正常或偏低。为了研究这种及其他激活突变，并完善对这种罕见疾病的分类，我们分析了另外6名詹森病患者的基因组DNA。
通过聚合酶链反应（PCR）扩增编码PTH - PTHrP受体的外显子，产物通过凝胶电泳或直接核苷酸序列分析进行检测。通过对基因组DNA或PCR产物进行限制性内切酶消化来确认核苷酸变化。
先前报道的将第223位的组氨酸变为精氨酸（H223R）的突变，在6名患者中的3名的基因组DNA中被发现，但在其健康亲属或45名无关正常受试者的DNA中未发现。在另一名患者中鉴定出一种新的错义突变，该突变将受体第六跨膜区的苏氨酸变为脯氨酸（T410P），但在62名正常受试者中未发现。在两名有詹森干骺端软骨发育不良影像学证据但高钙血症较轻的患者中，未检测到受体突变。在表达带有T410P或H223R突变的PTH - PTHrP受体的COS - 7细胞中，基础环磷酸腺苷积累比表达野生型受体的细胞高4至6倍。
在肾、骨和生长板软骨细胞中组成性激活的PTH - PTHrp受体的表达，为詹森病患者的矿物质离子异常和干骺端变化提供了一个合理的遗传学解释。
