Novel aberrant splicings caused by a splice site mutation (IVS1a+5g>a) in F7 gene

Qiulan Ding; Wenman Wu; Qihua Fu; Xuefeng Wang; Yiqun Hu; Hongli Wang; Zhenyi Wang

doi:10.1160/TH04-04-0220

Thrombosis and Haemostasis, Table of Contents

Thromb Haemost 2005; 93(06): 1077-1081
DOI: 10.1160/TH04-04-0220

Blood Coagulation, Fibrinolysis and Cellular Haemostasis

Schattauer GmbH

Novel aberrant splicings caused by a splice site mutation (IVS1a+5g>a) in F7 gene

Qiulan Ding^*

¹Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Second Medical University, Shanghai, People’s Republic of China

,

Wenman Wu^*

¹Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Second Medical University, Shanghai, People’s Republic of China

,

Qihua Fu

²Institute of Transfusion Medicine, Blood Center of Zhejiang Province, Hangzhou, Zhejiang, People’s Republic of China

,

Xuefeng Wang

¹Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Second Medical University, Shanghai, People’s Republic of China

,

Yiqun Hu

¹Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Second Medical University, Shanghai, People’s Republic of China

,

Hongli Wang

¹Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Second Medical University, Shanghai, People’s Republic of China

,

Zhenyi Wang

¹Shanghai Institute of Hematology, Ruijin Hospital, Shanghai Second Medical University, Shanghai, People’s Republic of China

› Author Affiliations

Abstract

Summary

Low FVII coagulant activity (FVII:C 8.2%) and antigen level (FVII:Ag 34.1%) in a 46-year-old Chinese male led to a diagnosis of coagulation factor VII (FVII) deficiency. Compound heterozygous mutations were identified in his F7 gene:a G to A transition in the 5’ donor splice site of intron 1a (IVS1a+5g>a) and a T to G transition at the nucleotide position 10961 in exon 8, resulting in a His to Gln substitution at amino acid residue 348. An analysis of ectopic transcripts of F7 in the leukocytes of the patient reveals that the mutation (IVS1a+5g>a) is associated with two novel aberrant patterns of splicing. The predominant alternative transcript removes exon 2, but retains intron 3, which shifts the reading frame and predicts a premature translation termination at the nucleotide positions 2–4 in intron 3. The minor alternative transcript skips both exon 2 and exon 3 (FVII Δ2, 3), leading to an in-frame deletion of the propeptide and γ-carboxylated glutamic acid (Gla) domains of mature FVII protein. In vitro expression studies of the alternative transcript FVII Δ2, 3 by transient transfection of HEK 293 cells with PcDNA 3.1(-) expression vector showed that although the mutant protein could be secreted, no pro-coagulation activity was detected. The coexistence of the two abnormal transcripts and a heterozygous mutation His348Gln, explained the patient’s phenotype.

Keywords

Factor VII deficiency - splice site mutation - exon skipping - intron retention

Full Text

References

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