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Background Hereditary angioedema (HAE) comprises HAE with C1-inhibitor deficiency (C1-INH-HAE) and HAE with normal C1-INH activity (nl-C1-INH-HAE), due to mutations in factor XII (FXII-HAE), plasminogen (PLG-HAE), angiopoietin 1 (ANGPT1-HAE), kininogen 1 genes (KNG1-HAE), or angioedema of unknown origin (U-HAE). The Italian network for C1-INH-HAE (ITACA) created a registry including different forms of angioedema without wheals. Objective We analyzed clinical and laboratory features of a cohort of Italian subjects with nl-C1-INH-HAE followed by ITACA to identify specific biomarkers. Methods A total of 105 nl-C1-INH-HAE patients were studied. Plasma concentrations of cleaved high-molecular-weight kininogen (cHK), vascular endothelial growth factors (VEGFs), angiopoietins (Angs), and secreted phospholipase A2 enzymes (sPLA2 ) were evaluated. Results We identified 43 FXII-HAE patients, 58 U-HAE, and 4 ANGPT1-HAE. We assessed a prevalence of 1:1.4 × 106 for FXII-HAE and 1:1.0 × 106 for U-HAE. cHK levels in U-HAE patients were similar to controls in plasma collected using protease inhibitors cocktail (PIC), but they significantly increased in the absence of PIC. In FXII-HAE patients, cHK levels, in the absence of PIC, were significantly higher than in controls. We found a significant increase of VEGF-A, VEGF-C, and Ang1 levels in U-HAE patients compared to controls. In FXII-HAE, only VEGF-C levels were increased. Ang2 concentrations and sPLA2 activity were not modified. The levels of these mediators in ANGPT1-HAE patients were not altered. Conclusions Our results suggest that pathogenesis of FXII-, ANGPT1-, and U-HAE moves through an unbalanced control of kallikrein activity, with bradykinin as most likely mediator. VEGFs and Ang1 participate in the pathophysiology of U-HAE increasing the basal vascular permeability.

Sporadic and familiar forms of non-histaminergic angioedema and normal C1 inhibitor encompass a group of disorders possibly caused by bradikinin. We aimed to study the subgroups of hereditary angioedema with FXII mutation (FXII-HAE), unknown genetic defect (U-HAE) and idiopathic non-histaminergic acquired angioedema (InH-AAE). We screened the F12 locus in our cohort and delineated the clinical, laboratory and genetic features. Four families carried the p.Thr309Lys mutation in F12 gene. Haplotyping confirmed the hypothesis of a common founder. Six families were affected by U-HAE and 13 patients by sporadic InH-AAE. C4 levels were significantly lower in FXII-HAE than in InH-AAE. In the FXII-HAE group, none had attacks exclusively in high estrogenic states; acute attacks were treated with icatibant. Prophylaxis with tranexamic acid reduced the attack frequency in most patients. Our study provides new data on the diagnosis, clinical features and treatment of non-histaminergic angioedema, underlying the role of the screening for F12 mutations.

Background Hereditary angioedema (HAE) is a rare genetic disease usually caused by mutation in the C1 inhibitor or the coagulation Factor XII gene. However, in a series of patients with HAE, no causative variants have been described, and the pathophysiology of the disease remains unknown (hereditary angioedema with yet unknown genetic defect [U-HAE]). Identification of causative genes in patients with U-HAE is valuable for understanding the cause of the disease. Objective We conducted genetic studies in Italian patients with U-HAE to identify novel causative genes. Methods Among patients belonging to 10 independent families and unrelated index patients with U-HAE recruited from the Italian Network for C1-INH-HAE (ITACA), we selected a large multiplex family with U-HAE and performed whole-exome sequencing. The angiopoietin-1 gene (ANGPT1) was investigated in all patients with familial or sporadic U-HAE. The effect of ANGPT1 variants was investigated by using in silico prediction and plasma and transfected cells from both patients and control subjects. Results We identified a missense mutation ( ANGPT1 , c.807G>T, p.A119S) in a family with U-HAE. The ANGPT1 p.A119S variant was detected in all members of the index family with U-HAE but not in asymptomatic family members or an additional 20 patients with familial U-HAE, 22 patients with sporadic U-HAE, and 200 control subjects. Protein analysis of the plasma of patients revealed a reduction of multimeric forms and a reduced ability to bind the natural receptor tunica interna endothelial cell kinase 2 of the ANGPT1 p.A119S variant. The recombinant mutated ANGPT1 p.A119S formed a reduced amount of multimers and showed reduced binding capability to its receptor. Conclusion ANGPT1 impairment is associated with angioedema, and ANGPT1 variants can be the basis of HAE.

We investigated the mutation spectrum of the phenylalanine hydroxylase gene (PAH) in a cohort of patients from 33 Italian PKU families. Mutational screening of the known coding region, including conventional intron splice sites, was performed by direct sequencing of the patients' genomic DNA. Thirty-three different disease causing mutations were identified in our patient group, including 19 missense, 6 splicing, 3 nonsense, 5 deletions, with a detection rate of 100%. The most prevalent mutation was the IVS10-11G>A, accounting for 12.1% of PKU alleles studied. Other frequent mutations were: p.R261Q (9.1%), p.P281L (7.6%), and p.R408W (6.1%). We also identified one novel missense mutation, p.H290Q. A spectrum of 31 different genotypes was observed and a genotype based predictions of BH4-responsiveness were assessed. Among all genotypes, 13 were predicted to be BH4-responsive represented by thirteen PKU families. In addition, genotype-phenotype correlations were performed. This study reveals the importance of a full genotyping of PKU patients and the prediction of BH4-responsiveness, not only because of the definitive diagnosis and prediction of the optimal diet, but also to point out those patients that could benefit from new therapeutic approach. They may potentially benefit from BH4 therapy which, combined with a less strict diet, or eventually in special cases as monotherapy, may contribute to reduce nutritional deficiencies and minimize neurological and psychological dysfunctions.

FAD synthetase (FADS) (EC 2.7.7.2) is a key enzyme in the metabolic pathway that converts riboflavin into the redox cofactor FAD. Two hypothetical human FADSs, which are the products of FLAD1 gene, were over-expressed in Escherichia coli and identified by ESI-MS/MS. Isoform 1 was over-expressed as a T7-tagged protein which had a molecular mass of 63 kDa on SDS–PAGE. Isoform 2 was over-expressed as a 6-His-tagged fusion protein, carrying an extra 84 amino acids at the N-terminal with an apparent molecular mass of 60 kDa on SDS–PAGE. It was purified near to homogeneity from the soluble cell fraction by one-step affinity chromatography. Both isoforms possessed FADS activity and had a strict requirement for MgCl 2 , as demonstrated using both spectrophotometric and chromatographic methods. The purified recombinant isoform 2 showed a specific activity of 6.8 ± 1.3 nmol of FAD synthesized/min/mg protein and exhibited a K M value for FMN of 1.5 ± 0.3 μM. This is the first report on characterization of human FADS, and the first cloning and over-expression of FADS from an organism higher than yeast.

We have studied the functional steps by which Saccharomyces cerevisiae mitochondria can synthesize FAD from cytosolic riboflavin (Rf). Riboflavin uptake into mitochondria took place via a mechanism that is consistent with the existence of (at least two) carrier systems. FAD was synthesized inside mitochondria by a mitochondrial FAD synthetase (EC 2.7.7.2), and it was exported into the cytosol via an export system that was inhibited by lumiflavin, and which was different from the riboflavin uptake system. To understand the role of the putative mitochondrial FAD carrier, Flx1p, in this pathway, an flx1Δ mutant strain was constructed. Coupled mitochondria isolated from flx1Δ mutant cells were compared with wild-type mitochondria with respect to the capability to take up Rf, to synthesize FAD from it, and to export FAD into the extramitochondrial phase. Mitochondria isolated from flx1Δ mutant cells specifically lost the ability to export FAD, but did not lose the ability to take up Rf, FAD, or FMN and to synthesize FAD from Rf. Hence, Flx1p is proposed to be the mitochondrial FAD export carrier. Moreover, deletion of the FLX1 gene resulted in a specific reduction of the activities of mitochondrial lipoamide dehydrogenase and succinate dehydrogenase, which are FAD-binding enzymes. For the flavoprotein subunit of succinate dehydrogenase we could demonstrate that this was not due to a changed level of mitochondrial FAD or to a change in the degree of flavinylation of the protein. Instead, the amount of the flavoprotein subunit of succinate dehydrogenase was strongly reduced, indicating an additional regulatory role for Flx1p in protein synthesis or degradation.

The accuracy of antemortem diagnosis of pulmonary embolism is within the range of just 10-30%, so representing one of the most frequent missed diagnosis in sudden, unexpected death. We describe 43 fatal cases of pulmonary embolism as confirmed by post-mortem examination. The aim of our study was to verify the systematic search for the most common genetic thrombophilias (Factor V Leiden (G1691A) and FII (G20210A) gene variants) and dating the thrombus. As a whole, 41 patients (95.3%) had at least one risk factor. Pre-existing symptoms are described just before fatal embolism in 18 (41.9%) out 43 patients. In 18 out of 43 (41.9%) it was not possible to find the thrombotic site. In 24 out of the remaining 25 cases the involvement of the deep veins of one leg was shown; in 1 case the thrombus was localised in the inferior caval vein. 10 (41.7%) were iliac vein thromboses, 7 (29.1%) femoral, 2 (8.3%) popliteal, 3 (12.6%) posterior-tibial, 1 (4.1%) anterior-tibial and 1 (4.1%) peroneal vein thromboses. In our cohort of patients, 4 (10%) out of 40 cases carried the 20210A prothrombin gene variant in heterozygosis. One (2.5%) out of 40 carried the Factor V Leiden (G1691A) gene variant in heterozygosis. Patients carrying these gene variants in homozygosis or carrying both were not present in our case-series. We strongly underline the relevance of a complete methodological approach, integrating clinical data by means of autopsy findings and histological study. On the contrary, investigating common inherited thrombophilia is not warranted.

Venous thrombosis (VT) represents a common and serious disorder that occurs as the result of clotting of the blood in the venous system and venous obstruction. Environmental risk factors and genetic predisposition play an important role in the development of thrombosis. It is therefore seen as a classic example of a complex common disease. We have focused on the role of genetic risk factors, primarily related to the hemostatic system, in triggering thrombotic events. Since the identification of antithrombin deficiency in 1965, major efforts have been made during the past 15 years to identify other genetic entities that lead to increased thrombotic risk. Results of early genetic studies demonstrated that two types of genetic defects cause VT: loss of function mutations in the natural anticoagulants antithrombin, protein C and protein S and gain of function mutations in procoagulant factors V (FV Leiden) and II (prothrombin G20210A). The high incidence of these mutations in Caucasians induced a shift from family studies to case-control association studies. Several investigations have been performed on the role of other candidate genetic risk factors predisposing to VT, including such variants in FXIII, FIX and fibrinogen genes. Moreover, the contribution of genetic variation in genes encoding less-well studied proteins that are part of the anticoagulant pathways has been evaluated. Recently, different genome-wide association studies have been performed in which several single nucleotide polymorphisms were investigated and related to the risk of VT. However, further studies are needed to identify additional genetic causes of thrombosis and to assess functional molecular mechanisms.