Expression Of Hemophilia Research Articles

Sustained Human Factor VIII Expression in Hemophilia A Mice Following Systemic Delivery of a Gutless Adenoviral Vector

Gutless adenoviral vectors are devoid of all viral coding regions and display reduced cytotoxicity, diminished immunogenicity, and an increased coding capacity compared with early generation vectors. Using hemophilia A, a deficiency in clotting factor VIII (FVIII), as a model disease, we generated and evaluated a gutless vector encoding human FVIII. The FVIII gutless vector grew to high titer and was reproducibly scaled-up from vector seed lots. Extensive viral DNA analyses revealed no rearrangements of the vector genome. A quantitative PCR assay demonstrated helper virus contamination levels of <2%, with the best preparation containing 0.3% helper virus. We compared the gutless vector with an E1/E2a/E3-deficient (Av3) early generation vector encoding an identical FVIII expression cassette following intravenous administration to hemophilia A mice. Gutless vector-treated mice displayed 10-fold higher FVIII expression levels that were sustained for at least 9 months. In contrast, mice treated with the Av3 vector displayed FVIII levels below the limit of sensitivity of the assay at 3 months. Assessment of hepatotoxicity by measuring the serum levels of liver enzymes demonstrated that the gutless vector was significantly less toxic than the Av3 vector at time points later than 7 days. At the highest dose used, both vectors caused a transient 10-fold increase in liver enzymes 1 day after vector administration, suggesting that this increase was caused by direct toxicity of the input capsid proteins. These data demonstrate that the gutless vector displayed increased duration and levels of FVIII expression, and was significantly less toxic than an analogous early generation vector.

Hemophilia B in a 46,XX female probably caused by non‐random X inactivation

A female whose father had severe hemophilia B was found to have a factor IX activity of about 1%. No chromosomal abnormality could be detected and DNA analysis gave no indications of deletions or mutations of Taq I cleavage sites in the factor IX gene. Analysis of the methylation pattern of locus DXS255 indicates that the expression of hemophilia B in this patient is caused by non-random X inactivation.

X-linked lymphoproliferative syndrome: Identification of a large family in Switzerland

Observation of a patient with acquired hypogammaglobulinemia associated with a mononucleosis syndrome led to the identification of one of the largest families affected by the X-linked lymphoproliferative (XLP) syndrome in the world. It is the first such family identified in Switzerland and the largest in Europe. At least nine male subjects over two generations presented phenotypic expressions consistent with the XLP syndrome. Study of the pedigree extending over seven generations suggests that the mutation occurred in the proband's great-grandmother. In the next generation, a second mutation of the X chromosome in one branch of the family resulted in expression of hemophilia A in the children. This remarkably large family, comprising six living obligate female carriers, displays a wide spectrum of the XLP syndrome and offers valuable information for future genetic linkage studies and for genetic counseling.