Low detection rate of antibodies to non-functional epitopes on factor VIII in patients with hemophilia A and negative for inhibitors by Bethesda assay

Summary.  In patients with hemophilia A who have an inhibitor to factor (F)VIII measured by Bethesda assay, enzyme-linked immunosorbent assay (ELISA) can also be used to detect the inhibitor. In some studies non-inhibitory antibodies were also detected by ELISA in many patients who were negative by Bethesda assay. Our aim was to investigate whether there is a higher detection rate of FVIII antibodies by ELISA compared with Bethesda assay. We also compared outcomes using three different preparations of recombinant FVIII (rFVIII) to coat the microtiter plates for ELISA. Inhibitor detection by ELISA generally agreed with the Bethesda method. Only four of 26 patients with no clinical suspicion of an inhibitor and with no detectable inhibitor by Bethesda assay showed a non-inhibitory antibody by ELISA, and three of these were only weakly positive. Patients with severe hemophilia A and the intron 22 inversion ( n  = 21) did not show a higher incidence of non-inhibitory antibodies compared with those without that mutation. Finally, we found that the formulation of rFVIII has a small effect on ELISA performance, mainly in detection of low-level antibody. The results of the present study are in contrast to and fail to confirm previously published reports showing a higher incidence of non-inhibitory antibodies in hemophilia A.     

Factor VIII (FVIII) gene mutations in 120 patients with hemophilia A: detection of 26 novel mutations and correlation with FVIII inhibitor development

BACKGROUND: As the publication of the sequence of the factor VIII gene (FVIII) in 1984, a large number of mutations that cause hemophilia A (HA) have been identified. Thanks to the advances in the detection of mutations, it is now possible to identify a putative FVIII sequence alteration in the vast majority of patients with HA.OBJECTIVES: Our main objective was to report on the spectrum of FVIII mutations and their distribution throughout the gene in 120 patients with HA. METHODS: Screening of FVIII mutations was performed using direct sequencing. Newly described missense mutations were further studied by molecular modeling. RESULTS: A total of 47 different HA causative FVIII mutations have been identified, 26 of which are described for the first time. These novel mutations include 14 missense and six nonsense mutations, two small deletions, one large deletion and three splice-site mutations. We further investigated the development of FVIII-specific inhibitors in all patients with HA. We found that four novel mutations (Ser882X, Tyr1786Ser, Ala2218Thr and a splice-site defect in intron 22) were associated with inhibitor development. CONCLUSION: These data extend our insight into the mechanisms by which novel amino acid substitutions may lead to HA, and how HA patient genotypes influence the risk of FVIII inhibitor development.     

呼吸道合胞病毒A与B亚型多重荧光PCR检测方法的建立及应用

目的建立一种新的呼吸道合胞病毒(RSV)分型检测方法,用于快速检测和监测。方法针对RSV G基因设计引物、探针,并引入人β-actin基因(ACTB)作为内参质控,建立RSV-A、RSV-B多重荧光PCR检测方法。使用多种常用呼吸道病原体及体外转录RNA产物考核其特异性和灵敏度。并对2015年1月至12月广州两家医院的儿童急性呼吸道感染患者进行检测。结果所建立的多重检测方法未见非特异性反应。RSV-A、RSV-B和ACTB分别可检测低至4、8和12 copies/μL的RNA模板,且分别在10~1×10~(10)copies/μL、100~1×10~(10)copies/μL和100~1×10~(10)copies/μL时具备良好的线性关系,线性相关系数r2均大于0.99。儿童急性呼吸道感染患者监测中,RSV-A为期间优势亚型。结论本研究所建立的RSV-A、RSV-B多重荧光PCR检测方法,具有较好的特异性、灵敏度、可操作性,可用于相关研究。     

NOTCH4 is a possible novel susceptibility gene for dilated cardiomyopathy in the Chinese population: A case‐control study

Background

The incidence of dilated cardiomyopathy (DCM) has increased in recent years, and many studies have sought to further improve the general understanding of this condition. Previous studies have demonstrated that some single nucleotide polymorphisms (SNPs) associated with systemic lupus erythematosus also affect susceptibility to DCM, suggesting that immune‐related diseases may share similar genetic susceptibility. Recent large‐scale and genome‐wide association studies have identified NCR3, NOTCH4, CYP1A2, ITGA1, OPRM1, ST8SIA2, and LINC00704 as genetic risk factors associated with cardiac manifestations of neonatal lupus. Here, we aimed to determine whether these SNPs conferred susceptibility to DCM in the Chinese Han population.

Methods

We investigated the relationship between these polymorphisms and DCM risk in 273 patients with DCM and 548 healthy controls. Genotyping was performed using MassArray iPLEX system.

Results

Logistic regression analysis indicated that the T allele of rs3134942 in NOTCH4 gene increased the risk of DCM by 61% compared with the G allele (P_a = 6.57 × 10⁻³). The SNP rs3134942 was also significantly associated with increased DCM risk in the additive (P_a = 6.57 × 10⁻³) and dominant models (P_a = 1.01 × 10⁻²). Additionally, rs2472299 in CYP1A2 gene showed suggestive association with reduced risk of DCM in the dominant model (P_a = 4.24 × 10⁻²) and was correlated with smoking status in patients with DCM (P_a = 1.56 × 10⁻²).

Conclusions

Our findings suggested that rs3134942 in NOTCH4 may be involved in DCM risk. Further, studies in larger and ethnically diverse populations are required to confirm the results reported in this study.