糖原累积症Ⅰb型15家系SLC37A4基因分析研究

Mutation in the SLC37A4 gene of glycogen storage disease type Ⅰ b in 15 families of the mainland of China

目的 研究中国人糖原累积症Ⅰb型SLC37A4基因突变状况.方法 对临床表现为肝大、空腹低血糖、高乳酸血症、高脂血症和粒细胞减少的15家系17例患者进行外周血DNA直接测序,分析SLC37A4基因突变情况.用限制性内切酶片段长度多态性方法对于新发现的错义突变给予分析判断.用RT-PCR方法对于新发现的剪切突变进行分析.并对患者的临床表现和基因型进行比较分析.结果 在15家系的17例患者的28个等位基因上共检测出11种突变和12种基因型,包括错义突变6个,p. Leu23Arg、p.Gly115Arg、p.Gly149Glu、p.Pro191Leu、p.Gly281Val和p.Arg415Gly;剪切突变2个,c,784＋1G＞A和c.870＋5G＞A;无义突变1个,p.Arg415X;缺失突变2个,c.1014_1120del107和c.1042_1043 del CT.突变p.Pro191Leu、p.Gly149Glu和c.870＋5G＞A为最常见突变,分别占37%,15%和11%.结论 从17例糖原累积症Ⅰb型中国患者中共检出突变11种,包括7种新突变,最常见突变为p.Pro191leu、p.Gly149Glu和c.870＋5G＞A.

Objective Glycogen storage disease type Ⅰ b （GSD Ⅰ b, MIM： 232220 ） is an autosomal recessive inborn error of metabolism caused by deficiency of the glucose-6-phosphate translocase.The clinical manifestations include symptoms and signs of both the typical GSD Ⅰ a, including hepatomegaly,fasting hypoglycemia, lactic acidemia and hyperlipedemia, and the dysfunction of neutrophils of recurrent infection and neutropenia. More than 84 mutations have been identified since the discovery of the SLC37A4 gene as the disease causing gene. Up to date, 5 mutations in 4 Chinese patients were reported from Hong Kang and Taiwan. In order to see the spectrum of the SLC37A4 gene mutations and the correlation between genotype and phenotype in patients with GSD Ⅰ b of the mainland of China, the authors investigated 17 GSD Ⅰ b patients from 15 families in this study. Method Data of 17 patients from 12 provinces, 11 male and 6 female, aged 6 months to 35 years, were collected from the genetic clinics of Peking Union Medical College Hospital from Oct. 2006 to Mar. 2009. All of them were Han Chinese in ethnicity. Consanguineous status was confirmed in 2 unrelated patients. All patients were presented with hepatomegaly, fasting hypoglycemia,lactic acidemia, hyperlipedemia and neutropenia with variable frequency of infections. The full coding exons, their relevant exon-intron boundaries, and the 5＇- and 3＇-flanking regions of the SLC37A4 gene were amplified and directly sequenced. RT-PCR was performed to verify the effect of the 2 novel splicing mutations. Result A total of 11 mutations were identified in 15 families. Four mutations, p. Gly149Glu,p. Pro191Leu,p. Arg415X and c. 1042_1043 del CT, were previously reported, and seven mutations, p.Leu23Arg, p. Gly115Arg, p. Gly281Val, p. Arg415Gly, c. 784 ＋ 1G ＞ A, c. 870 ＋ 5G ＞ A and c. 1014_1120del107, were novel. The frequent mutations are p. Pro191Leu, p. Gly149Glu and c. 870 ＋ 5G ＞ A,accounting for 37%, 15% and 11% of mutant alleles respectively. RT-PCR analysis of novel mutation c. 784 ＋ 1G ＞ A confirmed the splicing of exon 5 of 159 bp, causing inframe deletion. While mutation c. 870 ＋5G ＞ A was proved to cause exon 6, 86 bp, deletion causing frame-shift. Among 15 families, 12 genotypes were identified, including 3 with homozygous mutation and 9 with compound heterozygous mutations.Homozygous p. Pro191 Leu mutation was the only genotype detected in more than 1 family and was found in 4 unrelated families, including 1 patient from consanguineous marriage. Conclusion A total of 11 SLC37A4 gene mutations were identified in 15 families of the mainland of China. The frequent mutations are p. Pro191Leu,p. Gly149Glu and c. 870 ＋ 5G ＞ A. The number of Chinese SLC37A4 gene mutations was extended from 5 to 14.