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F Mingozzi

Publications and source records attributed to F Mingozzi.

8 recordsLinked to original sources
PubMed2005

Major role of local immune responses in antibody formation to factor IX in AAV gene transfer.

The risk of an immune response to the coagulation factor IX (F.IX) transgene product is a concern in gene therapy for the X-linked bleeding disorder hemophilia B. In order to investigate the mechanism of F.IX-specific lymphocyte activation in the context of adeno-associated viral (AAV) gene transfer to skeletal muscle, we injected AAV-2 vector expressing human F.IX (hF.IX) into outbred immune-competent mice. Systemic hF.IX levels were transiently detected in the circulation, but diminished concomitant with activation of CD4+ T and B cells. ELISPOT assays documented robust responses to hF.IX in the draining lymph nodes of injected muscle by day 14. Formation of inhibitory antibodies to hF.IX was observed over a wide range of vector doses, with increased doses causing stronger immune responses. A prolonged inflammatory reaction in muscle started at 1.5-2 months, but ultimately failed to eliminate transgene expression. By 1.5 months, hF.IX antigen re-emerged in circulation in approximately 70% of animals injected with high vector dose. Hepatic gene transfer elicited only infrequent and weaker immune responses, with higher vector doses causing a reduction in T-cell responses to hF.IX. In summary, the data document substantial influence of target tissue, local antigen presentation, and antigen levels on lymphocyte responses to F.IX.

Adenoviruses, Human↗
PubMed2001

Risk and prevention of anti-factor IX formation in AAV-mediated gene transfer in the context of a large deletion of F9.

The safety of several gene therapy approaches for treatment of the severe, X-linked bleeding disorder hemophilia is currently being evaluated in early phase clinical trials. One strategy seeks to correct deficiency of functional coagulation factor IX (hemophilia B) by intramuscular (IM) administration of an adeno-associated viral (AAV) vector. A potentially serious complication of any treatment for hemophilia is formation of inhibitory antibodies against the coagulation factor protein, a risk that increases in the setting of null mutations in the factor IX gene (F9). Here, we describe hemophilia B mice with a large F9 deletion that form inhibitors within 1 to 2 months after IM administration of an AAV vector expressing mouse F9 or after repeated intravenous infusion of mouse F9 concentrate. In both cases, inhibitors are primarily IgG1 immunoglobulins representing a Th2-driven humoral immune response. We further demonstrate that anti-mouse F9 antibody formation in the gene-based approach can be reduced by transient immune modulation at the time of vector administration. Moreover, this maneuver resulted in complete absence of anti-mouse F9 and sustained expression of functional mouse F9 in some hemophilia B mice, particularly in those animals treated with the immunosuppressive drug cyclophosphamide. These data have direct relevance for design of clinical trials and strategies aimed at avoiding immune responses against a secreted transgene product.

Animals↗
PubMed2001

A highly polymorphic microsatellite in the factor V gene is an informative tool for the study of factor V-related disorders.

The role of factor V (FV) mutations in activated protein C (APC) resistance and FV deficiency is well established. We report on the identification of a highly polymorphic (AT)n microsatellite marker in the FV gene, which represents an informative tool for the investigation of the origin and evolution of pathologically relevant FV genetic components. A high number of different microsatellite alleles were found to be associated with FV R506Q and FV H1299R, two single-origin mutations. An example of the use of the microsatellite marker in family studies of thrombophilia and FV deficiency is also provided.

Factor V↗
PubMed2001

A missense mutation (Y1702C) in the coagulation factor V gene is a frequent cause of factor V deficiency in the Italian population.

BACKGROUND AND OBJECTIVES: Factor V (FV) deficiency is a rare bleeding disorder whose molecular bases are poorly characterized. We have recently described a FV missense mutation (Y1702C) predicting reduced FV levels in a thrombophilic patient and in a healthy individual. The aim of the present work was to assess the prevalence of the FV Y1702C mutation among subjects with FV deficiency. DESIGN AND METHODS: Carriership of the FV Y1702C mutation was tested in 8 patients with severe FV deficiency (FV:C <8%), in 16 individuals with asymptomatic partial FV deficiency (mean FV:C 38.0%, SD 11.6%) and in 9 patients with pseudo-homozygous APC-resistance (mean FV:C 46.2%, SD 3.6%). An AccI-restriction protocol was employed for rapid mutation screening. RESULTS: The FV Y1702C mutation was detected in two unrelated patients with unmeasurable FV levels (one being homozygous and the other doubly heterozygous for a still unknown mutation) and in one subject with partial FV deficiency (FV:C 30%). A striking difference in bleeding phenotype was observed between the homozygous patient and her asymptomatic brother with the same FV genotype. A multi-point FV haplotype analysis was performed in all unrelated carriers of the FV Y1702C mutation. Three haplotypes were found to underlie the mutation in different individuals, suggesting that it might have arisen independently more than once. INTERPRETATION AND CONCLUSIONS: FV Y1702C is a common cause of FV deficiency in the Italian population and might be a recurrent mutation.

Adolescent↗
PubMed2000

Mutations in the R2 FV gene affect the ratio between the two FV isoforms in plasma.

Molecular genetics and biochemical studies were performed in homozygotes for the R2 allele (4070G) in the factor V gene, most of them affected by coronary artery disease. Novel polymorphisms (G642T, 156Ser; T1328C, 385Met/Thr), among which a functional candidate (A6755G, 2194Asp/Gly) located in the C2 domain of FV, were identified in the R2 gene. In chromatographic studies R2 FV appeared qualitatively identical to normal FV. However, a relative increase of the more thrombogenic and more glycosylated FV isoform (FV1) was observed in plasma of 2194Gly homozygotes (mean FV1/FV2 ratio 0.71, 95% CI 0.66-0.77) as compared to R2-free controls (0.37, 95% CI 0.34-0.40). We conclude that carriership of the R2 FV gene is associated with an imbalance between the two functionally different FV isoforms, and propose that genetically determined differential glycosylation of FV could represent a novel mechanism of thrombotic disease.

Aged↗
PubMed1997

New coagulation factor V gene polymorphisms define a single and infrequent haplotype underlying the factor V Leiden mutation in Mediterranean populations and Indians.

Two novel polymorphisms were identified in the factor V gene by direct sequencing of intronic areas. One of them, located in intron 9, is the marker closest to the Leiden mutation ever described, whereas the other, in intron 16, displays a rare allele invariantly associated to the mutation. Allele-specific amplification protocols were designed to perform extensive screenings for both polymorphic sites. The new markers were used in combination with six previously described polymorphisms to define specific factor V gene haplotypes. Haplotype investigations in 506Q homozygous thrombotic patients and normal controls showed the presence of a single haplotype underlying the factor V Leiden mutation in Mediterranean populations (among which Greek Cypriots, where the R506Q mutation is particularly frequent) and Indians. When traced in the absence of the Leiden mutation, the background haplotype was found to be present and roughly as frequent as the mutation itself in these populations. These findings indicate a single mutational event, that probably occurred outside Europe, as the cause of the Leiden mutation and provide a powerful tool to investigate its evolutionary history.

Cyprus↗