OBJECTIVE: To detect gene inversion in two pedigrees affected with Hemophilia A by using Nanopore sequencing technology. METHODS: Peripheral blood samples were taken from members of the two pedigrees. Following extraction of genome DNA, genetic variants of the carriers were detected by Nanopore sequencing and subjected to bioinformatic analysis. RESULTS: Nanopore sequencing has identified the niece of the proband of the pedigree 1 as carrier of Hemophilia A Inv22, and the mother of the proband of the pedigree 2 as carrier of Hemophilia A Inv1, which was consistent with clinical findings. Breakpoint sites in both pedigrees were accurately mapped. Statistical analysis of the sequencing results revealed a large number of variations in the carriers' genomes including deletions, duplications, insertions, inversions and translocations. CONCLUSION Nanopore sequencing can be used to analyze gene inversions associated with Hemophilia A, which also provided a powerful tool for the diagnosis of diseases caused by gene inversions.
Chromosome Inversion/genetics* ; Hemophilia A/genetics* ; Humans ; Introns ; Nanopore Sequencing ; Pedigree

Factor IX ; genetics ; Hemophilia B ; genetics ; Humans ; Male ; Mutation

OBJECTIVE: To screen better promoters and provide more powerful tools for basic research and gene therapy of hemophilia. METHODS: Bioinformatics methods were used to analyze the promoters expressing housekeeping genes with high abundance, so as to select potential candidate promoters. The GFP reporter gene vector was constructed, and the packaging efficiency of the novel promoter was investigated with EF1 α promoter as control, and the transcription and activities of the reporter gene were investigated too. The activity of the candidate promoter was investigated by loading F9 gene. RESULTS: The most potential RPS6 promoter was obtained by screening. There was no difference in lentiviral packaging between EF1 α-LV and RPS6-LV, and their virus titer were consistent. In 293T cells, the transduction efficiency and mean fluorescence intensity of RPS6pro-LV and EF1 αpro-LV were proportional to the lentiviral dose. The transfection efficiency of both promoters in different types of cells was in the following order: 293T>HEL>MSC; Compared with EF1 αpro-LV, RPS6pro-LV could obtain a higher fluorescence intensity in MSC cells, and RPS6pro-LV was more stable in long-term cultured HEL cells infected with two lentiviruses respectively. The results of RT-qPCR, Western blot and FIX activity (FIX∶C) detection of K562 cell culture supernatant showed that FIX expression in the EF1 α-F9 and RPS6-F9 groups was higher than that in the unloaded control group, and there was no significant difference in FIX expression between the EF1 α-F9 and RPS6-F9 groups. CONCLUSION After screening and optimization, a promoter was obtained, which can be widely used for exogenous gene expression. The high stability and viability of the promoter were confirmed by long-term culture and active gene expression, which providing a powerful tool for basic research and clinical gene therapy of hemophilia.
Humans ; Transduction, Genetic ; Genetic Vectors ; Hemophilia A/genetics* ; Transfection ; Blood Coagulation Factors/genetics* ; Lentivirus/genetics*

OBJECTIVETo detect potential mutation of F8 gene in a family affected with hemophilia type A.

METHODSInverse-shifting PCR (IS-PCR), next-generation sequencing (NGS), multiplex ligation-dependent probe amplification (MLPA), and short tandem repeat (STR) assays were used.

RESULTSIS-PCR showed that no inversion of F8 gene has occurred in the family. NGS detected no point mutation or small InDel in the proband, but suggested that the exon 2 of the F8 gene may be deleted. MLPA also showed that exon 2 of the F8 gene was absent in the proband, while the carriers were heterozygous for the deletion, though STR analysis yielded a paradoxical result.

CONCLUSIONNGS analysis has identified a large deletion of exon 2 of the F8 gene in a family affected with hemophilia A. Discretion is required when STR analysis was used for carrier screening and antenatal diagnosis. Combination of multiple methods can improve the accuracy for the detection of F8 gene mutations.

Child ; Exons ; genetics ; Factor VIII ; genetics ; Genetic Testing ; methods ; Hemophilia A ; Humans ; Male ; Pedigree ; Sequence Deletion ; genetics

OBJECTIVETo investigate the binding mechanisms of FVIII Trp1707Ser mutation-associated inhibitor.

METHODSThe APPT, PT, TT, Fg and FVIII:C were detected to make phenotypic diagnosis of haemophilia A. Inhibitors titer were measured by Bethesda method. Long distance-PCR (LD-PCR) and sequence-specific PCR were adopted for screening the intron 22 and intron 1 inversions respectively. FVIII coding and boundary sequences were analyzed by direct DNA sequencing. Inhibitor was reacted with different segments of FVIII, including heavy chain and its components A1 and A2, light chain and its components A3, C1 and C2. Corrected test was used to measure the remaining F VIII:C (% ) by adding pooled normal plasmas. After labeling purified inhibitors with biotin, western blot was performed to further confirm the binding reactions between inhibitors and segments.

RESULTSThe haemophilia A patient had mild deficiency of FVIII:C (1.1%) and had high FVIII inhibitor titer of 18.4 BU. A mutation c.97223C>G in exon 14 of F8 gene resulted to p.Trp1707Ser was identified by DNA sequencing. Corrected test showed that the remaining F VIII:C was increased when inhibitors reacted with heavy chain and light chain, especially with heavy chain. The remaining FVIII:C was also increased in the A2 and C2 domain reactions. No significant differences were seen in the A1, A3 and C1 domain reactions. Antigen-antibody reaction bands were confirmed by western blots when degenerated B-domain deleted recombinant FVIII, A2 and C2 were used as antigens.

CONCLUSIONThe binding sites of FVIIITrp1707Ser mutation inhibitor were the A2 domain of heavy chain and C2 domain of light chain. The binding reaction with heavy chain was more intense.

Binding Sites ; genetics ; Exons ; Factor VIII ; antagonists & inhibitors ; genetics ; Hemophilia A ; genetics ; Humans ; Male ; Mutation ; Young Adult

OBJECTIVE: To report on a case with severe hemophilia A (HA) due to a large duplication of F8 gene. METHODS: Inversion detection, Sanger sequencing, and multiplex ligation-dependent probe amplification (MLPA) were used to detect the mutation in the proband and his mother. RESULTS: The patient, a 7-year-old boy, was diagnosed with severe HA at 8 months. No inhibitor was developed over 150 exposure days. Intronic inversion detection and Sanger sequencing have failed to identify pathogenic variants, while MLPA revealed a large duplication [Ex 1_22 dup (2 copies)] in the proband, for which his mother was a carrier [Ex 1_22 dup (3 copies)]. Large duplications of the F8 gene have so far been found in 24 HA patients, all of whom had a severe phenotype, only one had a history of inhibitors. CONCLUSION Large duplications of F8 gene are associated with severe HA. The diagnostic rate for HA may be increased by MLPA.
Child ; Factor VIII/genetics* ; Gene Duplication ; Hemophilia A/genetics* ; Humans ; Introns ; Male ; Mutation ; Phenotype

OBJECTIVE: To investigate the relationship between the type of FⅧgene mutation and the development of FⅧ inhibitors in patients with severe haemophilia A (HA). METHODS: The medical records of 172 patients with severe hemophilia A from January 2009 to September 2020 were reviewed. The types of FⅧgene mutations and the production of factor Ⅷ inhibitors were collected and divided into high-risk mutation group ( intron 1 inversions, large deletions, nonsense mutations), low-risk mutation group (missense mutations, small deletions and insertions, splice site mutations) and intron 22 inversions group. The correlation of FⅧgenotype and the production of FⅧ inhibitors in patients with HA were analyzed. RESULTS: Among 172 patients with severe HA, 21 cases(12.21%) developed FⅧ inhibitors. The cumulative incidence of FⅧ inhibitor development was 32%(10/31) in high risk group (75% patients with large deletions, 43% patients with intron 1 inversions, 20% patients with nonsense mutations) and 5%(2/43) in low risk group(6% patients with missense mutations, 5% patients with small deletions or insertions and 0% patient with a splice site mutation) and 9%(9/98) in intron 22 inversions group. Compared with the risk of FⅧ inhibitor development in intron 22 inversions group, the risk of FⅧ inhibitor development in high risk group was higher (OR＝4.7, 95% CI： 1.7-13.0), the risk of FⅧ inhibitor development in low risk group was equal (OR＝0.5, 95% CI： 0.1-2.3). Compared with the risk of inhibitor development in low risk group, the risk of FⅧ inhibitor development in high risk group was higher (OR＝9.8, 95% CI： 2.0-48.7). CONCLUSION Gene mutations of patients with severe HA in high-risk group which include intron 1 inversions, large deletions, nonsense mutations are a risk factor for FⅧ inhibitor production.
Codon, Nonsense ; DNA Mutational Analysis ; Factor VIII/genetics* ; Hemophilia A/genetics* ; Humans ; Introns ; Mutation

OBJECTIVETo explore the immune tolerance induction (ITI) in a severe hemophilia A patient with inhibitor, and to improve the therapeutic efficacy for patient.

METHODSThe FVIII:C was assayed by one-stage method and FVIII antibody by Bethesda method. Mutation screening of FVIII gene intron 22 inversion was performed using LD-PCR.

RESULTSFVIII gene intron 22 inversion was detected in this patient. Clinical tolerance to FVIII was successfully induced after administration of the ITI regimen combined with immunosuppression. A fall of inhibitor titer from 8 BU to 0 BU after treatment for 3 months, and in vivo FVIII recovery (> 66%) was normalized. The patient had no bleeding episode in the following 6 months.

CONCLUSIONThis is the first case report on successful immune tolerance induction therapy in Chinese hemophilia A patient. ITI is the most effective therapy for hemophilia A with inhibitor.

Autoantibodies ; immunology ; Factor VIII ; genetics ; Hemophilia A ; genetics ; Humans ; Immune Tolerance ; drug effects ; Immunosuppression

OBJECTIVETo analyze intron 1 and 22 inversions in factor VIII (FVIII) gene in hemophilia A (HA) patients and and their families and to investigate the correlation between intron inversion and FVIII antibody.

METHODSAll patients were detected FVIII: C and FVIII antibody. In addition, 81 unrelated HA patients were directly detected by multiplex PCR and long-distance PCR for intron 1 and 22 inversions in FVIII gene. Pedigree investigation for some patients were conducted.

RESULTSIn 81 unrelated HA patients, 3 severe cases were found intron 1 inversion which accounted for 4.6% of total 65 severe cases. Of the 3 cases, one was FVIII antibody positive. Two female family members of a intron 1 inversion patient were identified as one carrier and one non-carrier. Twenty five of 65 (38.5%) severe cases were found intron 22 inversion. Of the 25 cases 1 was FVIII antibody positive. Nine female members in 5 HA families which had patients with intron 22 inversion were identified as 7 carries and 2 non-carriers.

CONCLUSIONBesides intron 22 inversion, intron 1 inversion was another important molecular defect in resulting in severe HA. Intron inversion analysis can also be used for deviation rectification of experiment grouping in HA patients. Intron 1 and 22 inversions may be one of the higher risk factors for resulting in FVIII antibodies.

Chromosome Inversion ; Chromosomes, Human, X ; Factor VIII ; genetics ; Female ; Hemophilia A ; genetics ; Humans ; Introns ; Male

OBJECTIVETo investigate the molecular mechanism of a Chinese hemophilia A patient in whom there was a discrepancy between the clinical bleeding symptoms and laboratory assay of FVIII activity (FVIII: C).

METHODSFVIII: C was detected by chromogenic and one-stage methods, and FVIII: Ag by ELISA. The APTT corrected test was used to screen the FVIII inhibitor and PCR amplification to analyze all the exons and flanking sequences of F8 gene of the proband, PCR products were purified and sequenced directly. The corresponding gene sites of family members were detected according to the gene mutation sites. Two B domain deleted human FVIII mutant expression plasmids His99Arg and His99Ala (pRC/RS V - BDhFVIIIcDNA) were constructed and transfected into HEK293T transiently. FVIII: Ag and FVIII: C of the expression products were assayed.

RESULTSThe proband APTT was prolonged, FVIII: Ag was 120% but FVIII: C <1% and no FVIII inhibitor in plasma. The results of anticoagulation and fibrinolytic functions were normal. The cross reacting material positive (CRM+) hemophilia A was diagnosed. Gene analysis revealed a A28828G substitution in exon 3 resulted in a H (His) to R (Arg) missense mutation and the same heterozygous was identified in his mother. In vitro expression of FVIII: Ag and FVIII: C of His99Arg were 180.0% and 5.8% , respectively, while FVIII: Ag and FVIII: C of His99Ala were 45.0% and 20.0% of that of wild type, respectively. His99Arg and His99Ala were diagnosed as CRM+ and CRM- mutations, respectively.

CONCLUSIONBoth the two F VIII mutations could express FVIII protein. However, CRM His99Arg mutant protein has little FVIII procoagulant activity and His99Ala has reduced FVIII function by routine methods.

Adult ; DNA Mutational Analysis ; Factor VIII ; genetics ; Genotype ; Hemophilia A ; etiology ; genetics ; Humans ; Male ; Mutation, Missense