Regulatory regions of SERPINC1 gene: Identification of the first mutation associated with antithrombin deficiency

Abstract

Antithrombin is the main endogenous anticoagulant. Impaired function or deficiency of this molecule significantly increases the risk of thrombosis. We studied the genetic variability of SERPINC1 , the gene encoding antithrombin, to identify mutations affecting regulatory regions with functional effect on its levels. We sequenced 15,375 bp of this gene, including the potential promoter region, in three groups of subjects: five healthy subjects with antithrombin levels in the lowest (75%) and highest (115%) ranges of our population, 14 patients with venous thrombosis and a moderate antithrombin deficiency as the single thrombophilic defect, and two families with type I antithrombin deficiency who had neither mutations affecting exons or flanking regions, nor gross gene deletions. Our study confirmed the low genetic variability of SERPINC1 , particularly in the coding region, and its minor influence in the heterogeneity of antithrombin levels. Interestingly, in one family, we identified a g.2143 C>G transversion, located 170 bp upstream from the translation initiation codon. This mutation affected one of the four regions located in the minimal promoter that have potential regulatory activity according to previous DNase footprinting protection assays. Genotype-phenotype analysis in the affected family and reporter analysis in different hepatic cell lines demonstrated that this mutation significantly impaired, although it did not abolish, the downstream transcription. Therefore, this is the first mutation affecting a regulatory region of the SERPINC1 gene associated with antithrombin deficiency. Our results strongly sustain the inclusion of the promoter region of SERPINC1 in the molecular analysis of patients with antithrombin deficiency.

Clinical and laboratory characteristics of antithrombin deficiencies: A large cohort study from a single diagnostic center

“…In the background of lower mutation detection rates in patients with low AT levels an aberrant N-glycosylation was hypothesized, or mutations in the regulatory sequences of SERPINC1 (eg. c.1-171C>G) were suggested [37][38][39]. Among our novel AT variants all mutations except for p.Pro461Thr showed a laboratory phenotype of type I deficiency.…”

Transient desialylation in combination with a novel antithrombin deficiency causing a severe and recurrent thrombosis despite anticoagulation therapy

“…Mutations in SERPINC1 , the gene encoding for antithrombin, were determined by sequencing the 7 exons and flanking regions, as well as the promoter region, using primers and conditions already described30.…”

Identification of 2 Novel Polymorphisms and rs3138521 in 5′ Untranslated Region of SERPINC1 Gene in North Indian Population With Deep Vein Thrombosis

“…This is the first report of AT genetic variations in regulatory region identified in Indian population with DVT and till now there is only 1 report showing polymorphism in the regulatory region of AT gene in caucasian population. 16 The heterozygous polymorphism, g.2085T>C, is located 228 bp upstream of translation initiation codon and was present in a patient with high plasma AT levels. Polymorphisms identified in the present study were located closer to the translation initiation codon and might explain severity of reduced circulatory AT levels when compared to that observed for g.2085T>C polymorphism.…”