Identification of factor VIII gene mutations in patients with severe haemophilia A in Venezuela: identification of seven novel mutations

Abstract

Haemophilia A is caused by mutations in the gene encoding coagulation factor VIII (FVIII). In severe Haemophilia A (sHA), two inversions are responsible for approximately 50% of the genetic alterations (intron 22 and intron 1 inversions). The other mutations are extremely diverse and each affected family generally has its own mutation. Our aim was to detect the genetic alterations present in the FVIII gene (F8) in 54 unrelated male patients with sHA in Venezuela. We initially detected the presence of the intron 22 inversion by performing inverse PCR, and the negative patients for this inversion were analysed for the intron 1 inversion by PCR. Patients negative for both inversions were analysed using Conformation Sensitive Gel Electrophoresis for mutations in all exons, promoter region and 3¢-UTR. sHA causative mutations were identified in 49 patients. Intron-22 and -1 inversions were detected in 41% and 0% of patients respectively. Besides these two mutations, 25 different mutations were identified, including nine nonsense, four small deletions, two small insertions, four missense, three splicing mutations and three large deletions. Seven novel mutations were identified, including two nonsense mutations, two small deletions, one small insertion, one missense mutation and one splicing mutation. Thirty one percent of the patients with identified mutations developed inhibitors against exogenous FVIII. This is the first report of F8 mutations in patients with sHA in Venezuela; the data from this study suggests that the spectrum of gene defects found in these patients is as heterogeneous as reported previously for other populations.

Factor 8 Gene Mutation Spectrum of 270 Patients with Haemophilia A: Identification of 36 Novel Mutations

“…This was achieved through following a protocol that involved up to three procedures: Inv22, Inv1, and F8 sequencing analyses. The frequencies of mutation types in our study are similar to those found in previous studies [7,23,24,25].…”

Mutation spectrum and inhibitor risk in 100 Korean patients with severe haemophilia A

“…A total of 61 patients (61%) had a point mutation detected using direct sequencing analyses. The prevalences of missense mutation and small deletion/insertion mutation were 17% and 23%, respectively, which is comparable with those in previous studies . Nonsense and missense mutations were distributed throughout the whole coding sequences of F8 , whereas frameshift mutations were present mainly in exon 14 (74%, 17/23), a hotspot for such mutations, because of the presence of several long polyadenine runs .…”

Spectrum of Molecular Defects in 216 Chinese Families With Hemophilia A: Identification of Noninversion Mutation Hot Spots and 42 Novel Mutations

“…Aside from Inv22, the most frequent mutation type resulting in severe hemophilia was point mutation (24.7%, 46 of 186), including missense mutation, nonsense mutation, and splice-site changes; this was followed by small deletion/insertion mutations (15.6%, 29 of 186). The prevalence was compatible with the rates observed in previous studies, [12][13][14] and as expected, all of the null mutations were associated with the severe hemophilia, whereas missense mutations were responsible for all levels of HA severity. Despite using multiple techniques, no mutations were identified in the remaining 7 severe individuals; in these cases, the mutations may have been located deep within introns or in regions outside of F8 that were important for its expression.…”