Manderstedt Eric, Lind-Halldén Christina, Lethagen Stefan, Halldén Christer
Biomedicine, Kristianstad University, Kristianstad, Sweden.
University of Copenhagen, Copenhagen, Denmark.
PLoS One. 2018 Feb 1;13(2):e0192024. doi: 10.1371/journal.pone.0192024. eCollection 2018.
von Willebrand factor (VWF) levels in healthy individuals and in patients with type 1 von Willebrand disease (VWD) are influenced by genetic variation in several genes, e.g. VWF, ABO, STXBP5 and CLEC4M. This study aims to screen comprehensively for CLEC4M variants and investigate their association with type 1 VWD in the Swedish population. In order to screen for CLEC4M variants, the CLEC4M gene region was re-sequenced and the polymorphic neck region was genotyped in 106 type 1 VWD patients from unrelated type 1 VWD families. Single nucleotide variants (SNV) and variable number tandem repeat (VNTR) allele and genotype frequencies were then compared with 294 individuals from the 1000Genomes project and 436 Swedish control individuals. Re-sequencing identified a total of 42 SNVs. Rare variants showed no accumulation in type 1 VWD patients and are not thought to contribute substantially to type 1 VWD. The only missense mutation (rs2277998, NP_001138379.1:p.Asp224Asn) had a higher frequency in type 1 VWD patients than in controls (4.9%). The VNTR genotypes 57 and 67 were observed at higher frequencies than expected in type 1 VWD patients (6.4% and 6.2%) and showed an increase in patients compared with controls (7.4% and 3.1%). Strong linkage disequilibrium in the CLEC4M region makes it difficult to distinguish between the effect of the missense mutation and the VNTR genotypes. In conclusion, heterozygous VNTR genotypes 57 and 67 of CLEC4M were highly enriched and are the most likely mechanism through which CLEC4M contributes to disease in the Swedish type 1 VWD population.
健康个体和1型血管性血友病（VWD）患者的血管性血友病因子（VWF）水平受多个基因（如VWF、ABO、STXBP5和CLEC4M）的遗传变异影响。本研究旨在全面筛查CLEC4M变异，并调查其与瑞典人群中1型VWD的关联。为了筛查CLEC4M变异，对106例来自无关1型VWD家族的1型VWD患者的CLEC4M基因区域进行了重测序，并对多态性颈部区域进行了基因分型。然后将单核苷酸变异（SNV）和可变数目串联重复序列（VNTR）等位基因及基因型频率与来自千人基因组计划的294名个体和436名瑞典对照个体进行比较。重测序共鉴定出42个SNV。罕见变异在1型VWD患者中未出现聚集，被认为对1型VWD的影响不大。唯一的错义突变（rs2277998，NP_001138379.1:p.Asp224Asn）在1型VWD患者中的频率高于对照组（4.9%）。VNTR基因型57和67在1型VWD患者中的观察频率高于预期（6.4%和6.2%），且与对照组相比患者中有所增加（7.4%和3.1%）。CLEC4M区域的强连锁不平衡使得难以区分错义突变和VNTR基因型的影响。总之，CLEC4M的杂合VNTR基因型57和67高度富集，是CLEC4M在瑞典1型VWD人群中导致疾病的最可能机制。
