Department of Internal Medicine D, Rabin Medical Center, Beilinson Hospital, Petah Tikva, Israel.
J Med Genet. 2011 Jun;48(6):383-9. doi: 10.1136/jmg.2010.087114. Epub 2011 Apr 14.
This study reports on a hitherto undescribed autosomal recessive syndrome characterised by dysmorphic features and multiple congenital anomalies together with severe neurological impairment, chorea and seizures leading to early death, and the identification of a gene involved in the pathogenesis of the disease.
Homozygosity mapping was performed using Affymetrix Human Mapping 250k NspI arrays. Sequencing of all coding exons of the candidate genes was performed with primer sets designed using the Primer3 program. Fluorescence activated cell sorting was performed using conjugated antibody to CD59. Staining, acquisition and analysis were performed on a FACSCalibur flow cytometer.
Using homozygosity mapping, the study mapped the disease locus to 18q21.32-18q22.1 and identified the disease-causing mutation, c.2126G→A (p.Arg709Gln), in PIGN, which encodes glycosylphosphatidylinositol (GPI) ethanolamine phosphate transferase 1, a protein involved in GPI-anchor biosynthesis. Arginine at the position 709 is a highly evolutionarily conserved residue located in the PigN domain. The expression of GPI linked protein CD59 on fibroblasts from patients as compared to that in a control individual showed a 10-fold reduction in expression, confirming the pathogenic consequences of the mutation on GPI dependent protein expression.
The abundant expression of PIGN in various tissues is compatible with the diverse phenotypic features observed in the patients and with the involvement of multiple body systems. The presence of developmental delay, hypotonia, and epilepsy combined with multiple congenital anomalies, especially anorectal anomalies, should lead a clinician to suspect a GPI deficiency related disorder.
本研究报告了一种以前未描述的常染色体隐性综合征，其特征为畸形特征和多种先天性异常，以及严重的神经损伤、舞蹈病和癫痫发作，导致早期死亡，并确定了参与疾病发病机制的基因。
使用 Affymetrix Human Mapping 250k NspI 阵列进行纯合子作图。使用 Primer3 程序设计的引物组对候选基因的所有编码外显子进行测序。使用与 CD59 结合的抗体进行荧光激活细胞分选。在 FACSCalibur 流式细胞仪上进行染色、采集和分析。
使用纯合子作图，该研究将疾病定位到 18q21.32-18q22.1，并确定了致病突变 c.2126G→A（p.Arg709Gln），该突变位于编码糖基磷脂酰肌醇（GPI）乙醇胺磷酸转移酶 1 的 PIGN 中，该蛋白参与 GPI-锚生物合成。位置 709 的精氨酸是一个高度进化保守的残基，位于 PigN 结构域中。与对照个体相比，患者成纤维细胞中 GPI 连接蛋白 CD59 的表达减少了 10 倍，证实了突变对 GPI 依赖性蛋白表达的致病后果。
PIGN 在各种组织中的大量表达与患者观察到的多种表型特征以及多个身体系统的参与是一致的。发育迟缓、低张力和癫痫发作与多种先天性异常并存，特别是肛门直肠异常，应使临床医生怀疑存在 GPI 缺乏相关疾病。
