糖原累积病Ⅰa型的基因突变和临床研究

Gene mutation and clinical study in the patients with glycogen storage disease type Ⅰa

目的 了解中国人葡萄糖 6 磷酸酶 (G6Pase)基因突变谱和突变热点 ,并分析糖原累积病Ⅰa型 (GSDⅠa)基因型和临床表型的相关性。方法 采用PCR、DNA序列分析、家系分析和限制性内切酶图谱分析等方法对 2 1例GSDⅠa患者G6Pase基因进行分析。结果 42个G6Pase等位基因中 ,发现72 7G→T突变 3 4个 (80 .95 % ) ,R83H突变 4个 (9.5 2 % ) ,R170X ,Q10 4X和 3 41delG突变各 1个。 2 1例患者中 13例患者为 72 7G→T纯合突变 ,8例为杂合突变 ,72 7G→T和R83H突变经限制性内切酶图谱分析证实。相同基因型的患者从发病年龄到血生化指标和症状的严重程度均有所不同 ,1例 72 7G→T纯合突变患者发生肝腺瘤。结论 通过分子生物学方法进行 72 7G→T和R83H突变的筛查可发现近 90 %的G6Pase基因突变。根据GSDⅠa典型的临床表型及生化指标结合突变检测 ,此筛查可取代有创性肝穿刺酶活性检测的确诊方法。

Objective To obtain the mutation spectrum of glucose-6-phosphatase (G6Pase) gene in Chinese patients with glycogen storage disease type Ⅰa (GSDⅠa) and to analyze the relationship of its genotype and phenotype. Methods Genomic DNA samples were extracted from peripheral blood of 21 GSDⅠa patients from 19 families, their parents and 21 normal individuals. Five exons of G6Pase gene were analyzed in patients by PCR, direct DNA sequencing, family analysis and restriction enzyme analysis. Results The most prevalent mutation was 727G→T, accounting for 34 (80.95%) of 42 alleles examined, followed by R83H mutation, which accounted for 4 (9.52%) mutant alleles. Three other mutations, R170X, Q104X, 341delG were identified. Thirteen patients were homozygotes for 727G→T. Eight patients were heterozygotes for 727G→T. The 727G→T and R83H mutations were also confirmed by restriction enzyme analysis. The 653A→G homozygous transition was found in all the 21 patients, 33 parents of patients and 21 normal individuals. From clinical and biochemical aspects, the phenotypic heterogeneity was observed in the patients with the same genotype. Hepatic adenoma was detected in 1 patient of 727G→T homozygote. Conclusion A screening for the 727G→T and R83H mutations by DNA-based diagnostic methods can detect 90% of the G6Pase mutant alleles in Chinese patients with GSDⅠa. Combined with clinical and biochemical characters, the noninvasive molecular diagnosis for GSDⅠa may ultimately replace the conventional means of enzymatic diagnosis that requires liver biopsy.