Protein modelling to understand FGB mutations leading to congenital hypofibrinogenaemia.

INTRODUCTION: Congenital hypofibrinogenaemia is a quantitative fibrinogen disorder characterized by proportionally decreased levels of functional and antigenic fibrinogen. Mutations accounting for quantitative fibrinogen disorders are relatively frequent in the conserved COOH-terminal globular domains of the γ and Bß chains. The latter mutations are of particular interest since the Bß-chain is considered the rate-limiting chain in the hepatic production of the fibrinogen hexamer. AIM: The aim of this study was to study the molecular pattern of four patients with congenital hypofibrinogenaemia. METHODS: Four novel fibrinogen Bß-chain mutations leading to congenital hypofibrinogenaemia were identified in four women with heterogeneous symptoms. The human fibrinogen beta chain precursor protein sequence (P02675) was obtained from the UniProt database. The resulting models were analysed using swisspdbviewer 4.1.0. RESULTS: Three patients were heterozygous for different missense mutations located in the highly conserved ß nodule: c.882G>C:Arg294Ser (Arg264Ser), c.1298G>T:Trp433Leu (Trp403Leu) and c.1329C>G:Asn443Lys (Asn413Lys). Modelling analyses predicted major structural modifications likely to result in impaired fibrinogen secretion. One patient was heterozygous for an intron 7 donor splice mutation (c.1244 + 1G>A), leading to the complete abolishment of the donor site. CONCLUSIONS: Protein modelling of new causative mutations and comparison of molecular, biochemical and clinical data continue to yield valuable information on the development and course of fibrinogen disorders as well as on the choice of the most appropriate treatments.

Outcome of hematopoietic stem cell transplantation is similar for patients with a partial in vitro T-cell-depleted graft compared with a non-T-cell-depleted graft when stratified by the refined disease risk index.

Comparisons of hematopoietic stem cell transplantation (HSCT) methods in retrospective studies are often hampered by the heterogeneity of comparison groups. The refined disease risk index (DRI) is a potentially interesting tool to compare HSCT protocols as it is based on the disease type and burden at transplant and stratifies patients into four prognostic groups for overall survival (OS). We included 265 patients with partial T-cell-depleted graft (TDEP) and 163 non-TDEP patients in a retrospective study and compared outcomes following stratification using the refined DRI. The 2-year OS rate for TDEP patients was 81.6, 60.9 and 43.3% for the low-, intermediate- and high-risk groups, respectively (P<0.001). For non-TDEP patients, the 2-year OS rate was 62.9, 48.8, 44.2 and 7.6% for the low-, intermediate-, high- and very-high-risk groups, respectively (P<0.001). There was no significant difference when comparing OS between TDEP and non-TDEP for the low-, intermediate- and high-risk groups, but TDEP patients had less acute GvHD grades II-IV. In conclusion, we confirm that the refined DRI is a valuable tool to compare the outcomes of different HSCT protocols. We demonstrate also that TDEP did not impact on the outcome of HSCT, but it did reduce the incidence of acute GvHD.