Tan F K, Wang N, Kuwana M, Chakraborty R, Bona C A, Milewicz D M, Arnett F C
The University of Texas-Houston Medical School, 77030, USA.
Arthritis Rheum. 2001 Apr;44(4):893-901. doi: 10.1002/1529-0131(200104)44:4<893::AID-ANR146>3.0.CO;2-3.
Previously, we demonstrated with the use of microsatellite markers that a 2-cM haplotype on chromosome 15q containing the fibrillin 1 gene (FBN1) was strongly associated with systemic sclerosis (SSc) in the Choctaw, a population with high SSc prevalence. In this study, all 69 known FBN1 exons were sequenced to ascertain the presence of changes that might show associations with SSc in the Choctaw and Japanese SSc patients and controls.
Screening of FBN1 exons was accomplished by polymerase chain reaction-based fluorescence sequencing of genomic DNA using single-nucleotide polymorphism (SNP) haplotypes, and their frequencies were determined with a new algorithm that recognizes past recombination events between sites. Haplotype phylogenies were inferred using the median-joining network analysis.
Five SNPs were identified in FBN1. They are located in the 5'-untranslated region (SNP-1), exon 15 (SNP-2), intron 17 (SNP-3), exon 27 (SNP-4), and intron 27 (SNP-5). Only SNP-1 (T-->C) demonstrated an association with SSc in the Choctaw. Eleven FBN1 SNP haplotypes were ascertained in the Choctaw population, 2 of which (SNPs 5 and 6) were found only in the SSc patients. These same FBN1 SNP haplotypes were associated with SSc in the Japanese.
A SNP in the 5'-untranslated region of FBN1 (SNP-1, C allele) was strongly associated with SSc in the Choctaw. Furthermore, this polymorphism is present on 2 unique FBN1 haplotypes found only in Choctaw SSc patients. The same 2 haplotypes demonstrate associations with SSc in the Japanese. These data extend the earlier microsatellite studies and are consistent with the hypothesis that FBN1 or a nearby gene on chromosome 15q is involved in SSc susceptibility in the Choctaw and the Japanese.
此前，我们利用微卫星标记证明，在15号染色体上包含原纤蛋白1基因（FBN1）的一个2厘摩单倍型与乔克托族人群中的系统性硬化症（SSc）密切相关，该人群中SSc患病率较高。在本研究中，对所有69个已知的FBN1外显子进行测序，以确定可能与乔克托族和日本SSc患者及对照中的SSc相关的变化。
通过基于聚合酶链反应的基因组DNA荧光测序，利用单核苷酸多态性（SNP）单倍型对FBN1外显子进行筛选，并使用一种识别位点间过去重组事件的新算法确定其频率。使用中介连接网络分析推断单倍型系统发育。
在FBN1中鉴定出5个SNP。它们位于5'非翻译区（SNP-1）、外显子15（SNP-2）、内含子17（SNP-3）、外显子27（SNP-4）和内含子27（SNP-5）。只有SNP-1（T→C）在乔克托族中显示出与SSc相关。在乔克托族人群中确定了11种FBN1 SNP单倍型，其中2种（SNP 5和6）仅在SSc患者中发现。这些相同的FBN1 SNP单倍型在日本人中也与SSc相关。
FBN1的5'非翻译区中的一个SNP（SNP-1，C等位基因）在乔克托族中与SSc密切相关。此外，这种多态性存在于仅在乔克托族SSc患者中发现的2种独特的FBN1单倍型上。相同的2种单倍型在日本人中也显示出与SSc相关。这些数据扩展了早期的微卫星研究，并且与FBN1或15号染色体上附近的基因参与乔克托族和日本人的SSc易感性这一假设一致。
