Deficiency in the A-subunit of coagulation factor XIII: two novel point mutations demonstrate different effects on transcript levels.
Deficiency in the A-subunit of coagulation factor XIII: two novel point mutations demonstrate different effects on transcript levels.
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凝血因子 XIII A 亚基缺乏：两种新的点突变表现出对转录水平的不同影响。
作者：
H. Mikkola;Martti Syrjälä;Vesa Rasi;Elina Vahtera;E. Hämäläinen;Leena Peltonen;A. Palotie
先天性凝血因子 XIII 缺乏是一种罕见的常染色体隐性出血性疾病。尽管这种缺陷在 30 多年前就已被定性，但人们对这种疾病的分子基础知之甚少。在这里，我们展示了芬兰基因隔离人群中因子 XIII A 亚基基因的两个新点突变。对芬兰发现的所有 8 个因子 XIII 缺乏的家庭进行了研究。通过聚合酶链式反应单独扩增A亚基基因的外显子，随后通过单链构象多态性进行筛选。异常迁移片段的序列分析显示两个点突变导致氨基酸改变。外显子 XIV 中 Arg-661 处的 C 到 T 转换产生了提前终止密码子。在 8 个家族中的 6 个家族中检测到了这种突变，因此是导致芬兰 FXIII 缺陷的主要突变。在这六个家庭中的两个中，患者是复合杂合子，一个等位基因中存在 Arg-661-Stop 突变，而外显子 VI 中存在 T 到 C 点突变，或者另一个等位基因中存在迄今为止未表征的突变。外显子 VI 中的 T 到 C 转变导致 242 号蛋氨酸被苏氨酸取代。这种转变仅在一个家族中发现，该家族以杂合子形式与 Arg-661-Stop 突变相结合。为了评估这些突变的后果，通过固相微型测序对稳态 FXIII mRNA 水平进行了定量。除了在初始终止密码子之前 70 个氨基酸处终止翻译之外，Arg-661-Stop 突变还会导致 FXIII mRNA 水平降低 10 至 30 倍。这也可能导致截短的多肽翻译水平低。相反，Met-242-Thr突变似乎不影响mRNA水平。这里，功能性和免疫可检测蛋白质的缺失可能是由突变多肽的构象改变引起的，导致缺陷蛋白质的早期降解。
Congenital deficiency in coagulation factor XIII is a rare autosomal recessive bleeding disorder. Although the defect was characterized over 30 years ago, little is known about the molecular basis of the disorder. Here, we show two novel point mutations in the gene of the A-subunit of factor XIII in the genetically isolated population of Finland. All eight factor XIII-deficient families identified in Finland were studied. The exons of the gene of A-subunit were amplified individually by polymerase chain reaction and subsequently screened by single-strand conformation polymorphism. Sequence analysis of the abnormally migrating fragments showed two point mutations resulting in an amino acid alteration. A C-to-T transition at Arg-661 in exon XIV created a premature stop codon. This mutation was detected in six of the eight families, thus being the major alteration causing FXIII deficiency in Finland. In two of the six families, the patients were compound heterozygotes with the Arg-661-Stop mutation in one allele and either a T-to-C point mutation in exon VI or a thus far uncharacterized mutation in the other allele. The T-to-C transition in exon VI resulted in a substitution of threonine for methionine 242. The transition was found in one family only, where it was in the heterozygote form combined with the Arg-661-Stop mutation. To evaluate the consequences of these mutations, steady-state FXIII mRNA levels were quantitated by solid-phase minisequencing. In addition to the termination of translation 70 amino acids before the initial stop codon, the Arg-661-Stop mutation causes a 10- to 30-fold reduction in FXIII mRNA levels. This is also likely to result in a low translation level in the truncated polypeptide. In contrast, Met-242-Thr mutation does not seem to affect the level of mRNA. Here, the absence of a functional and immunodetectable protein is probably caused by an altered conformation of the mutant polypeptide, resulting in early degradation of the defective protein.
人因子 XIII b 亚基基因的核苷酸序列。
影响因子：
2.9
作者：
Bottenus,RE;Ichinose,A;Davie,EW
通讯作者：
Davie,EW
凝血因子 XIII 的 b 亚基完全缺乏的患者存在两种遗传缺陷。
影响因子：
20.3
作者：
Hashiguchi,T;Saito,M;Morishita,E;Matsuda,T;Ichinose,A
通讯作者：
Ichinose,A