The Centers for Disease Control and Prevention (CDC) Nijmegen‐Bethesda Assay (NBA)1 is a modification of traditional methods2., 3. for measurement of factor VIII (FVIII) and factor IX (FIX) inhibitors that includes a 30‐minute preanalytical heat treatment (PHT) step to remove endogenous and infused FVIII or FIX. Specimens for inhibitor tests using PHT thus do not require the stringent conditions needed to maintain clotting factors during shipping and storage, as we have previously documented by split‐sample analysis showing that results of the CDC‐modified NBA on specimens shipped cold correlated well with those of frozen specimens.1

Development of antibodies interfering with the function of factor VIII (FVIII) replacement products is one of the most significant complications in the treatment of hemophilia A (HA). Laboratory testing for such antibodies, called inhibitors, is an important part of hemophilia care and is conducted both to identify the cause of treatment failure and as routine screening to detect early antibody appearance. Treatment of HA patients who develop inhibitors is often carried out by giving repeated doses of FVIII to induce immune tolerance and allow use of FVIII or by use of by-passing agents that act by facilitating coagulation without the need for FVIII. The newest by-passing product, emicizumab (Hemlibra®), is a bispecific antibody that mimics the function of FVIII by bringing factor IXa and factor X (FX) together to produce the Xa complex.1,2 Emicizumab, which is long acting and given subcutaneously, is now widely available for use in patients both with and without inhibitors to avoid frequent use of intravenous FVIII replacement.

Emergency response to emerging threats with the potential for vertical transmission, such as the 2015 to 2017 response to Zika virus, presents unique clinical challenges that underscore the need for better communication and care coordination between obstetric and pediatric providers to promote optimal health for women and infants. Published guidelines for routine maternal-infant care during the perinatal period, and models for transitions of care in various health care settings are available, but no broad framework has addressed coordinated multidisciplinary care of the maternal-infant dyad during emergency response. We present a novel framework and strategies to improve care coordination and communication during an emergency response. The proposed framework includes (1) identification and collection of critical information to inform care, (2) key health care touchpoints for the maternal-infant dyad, and (3) primary pathways of communication and modes of transfer across touchpoints, as well as practical strategies. This framework and associated strategies can be modified to address the care coordination needs of pregnant women and their infants with possible exposure to other emerging infectious and noninfectious congenital threats that may require long-term, multidisciplinary management. KEY POINTS: . Emerging congential threats present unique coordination challenges for obstetric and pediatric clinicians during emergency response.. . We present a framework to help coodinate care of pregnant women/infants exposed to congenital threats.. . The framework identifies critical information to inform care, health care touchpoints, and communication/information transfer pathways..

Detection of low-titer factor VIII (FVIII) or factor IX (FIX) inhibitors can be difficult in the presence of endogenous or therapeutic factor.1 Pre-analytic heat treatment (PHT) of patient plasma specimens at 56⁰C for 30 minutes followed by centrifugation prior to measurement of the inhibitor titer is important to eliminate interference caused by endogenous or therapeutic factor in the specimen and to avoid the need for a washout period.1 PHT has been previously shown to enable more accurate determination of the inhibitor titer without removing antibodies in the context of traditional factor replacement products.2

The Nijmegen-Bethesda assay (NBA) is the gold standard for measurement of factor VIII (FVIII) inhibitors in haemophilia A patients.1 Modification of the traditional NBA2 to use a chromogenic measurement of FVIII as the endpoint is necessary for measurement of FVIII inhibitors in the presence of heparin, lupus anticoagulants, or by-passing agents such as emicizumab, due to their interference in clot-based assays.3–5 Parallel testing has shown this modification to produce similar results to the NBA in the absence of these interfering substances.6 In the clot-based NBA, substitution of imidazole-buffered bovine serum albumin (IB-BSA) for FVIII-deficient plasma (FVIIIDP) as diluent in control mixtures and specimen dilutions has been shown to produce equivalent results when the threshold for positivity was slightly adjusted.7 This study aims to evaluate a similar substitution in the chromogenic Bethesda assay (CBA) and to describe the performance characteristics of this modified assay.

Two sickle cell disease (SCD) phenotypes, HbSS and HbSβ0 thalassaemia, are believed to be so similar in disease severity that all major paediatric National Institute of Health randomized controlled trials include both (Wang et al, 2011; DeBaun et al, 2014; Brousseau et al, 2015). However, data from our group and others suggest the two diagnoses are associated with different clinical courses (Serjeant et al, 1979; Zago et al, 1980), highlighting the importance of accurately distinguishing the two. In a cross-sectional study, we tested two hypotheses: (i) a subset of phenotypic diagnoses of HbSβ0 thalassaemia and HbSS are discordant with their genotypic diagnoses; and (ii) phenotypic misclassification of HbSβ0 thalassaemia is associated with alpha-chain deletions.

The Nijmegen-Bethesda assay (NBA), considered the “gold standard” for measurement of factor VIII (FVIII) inhibitors in haemophilia A,1 introduced two modifications to the traditional Bethesda assay (BA) for stabilization during the 2-hour incubation at 37°C: (i) buffering of normal pooled plasma (NPP) in the test and control mixtures with imidazole and (ii) substitution of FVIII-deficient plasma (FVIIIDP) for imidazole buffer (IB) in the control mixture and for specimen predilution.2 The NBA has not been widely adopted in the United States, because of the increased cost incurred by use of FVIIIDP rather than buffer and the lack of FDA-approved commercial reagents.3 Surveys of North American coagulation laboratories have shown that only 20% use the NBA, 70% use buffered NPP in a “hybrid” of the NBA and BA, and one-third use diluents other than those recommended in published methods.3 This lack of methodological uniformity may partially account for poor interlaboratory reproducibility, a well-known problem with FVIII inhibitor testing.3

The current outbreak of Zika virus (ZIKV) infection has been associated with an apparent increased risk of congenital microcephaly. We describe a case of a pregnant woman and her fetus infected with ZIKV during the 11th gestational week. The fetal head circumference decreased from the 47th percentile to the 24th percentile between 16 and 20 weeks of gestation. ZIKV RNA was identified in maternal serum at 16 and 21 weeks of gestation. At 19 and 20 weeks of gestation, substantial brain abnormalities were detected on ultrasonography and magnetic resonance imaging (MRI) without the presence of microcephaly or intracranial calcifications. On postmortem analysis of the fetal brain, diffuse cerebral cortical thinning, high ZIKV RNA loads, and viral particles were detected, and ZIKV was subsequently isolated.

Hemophilia B (HB) is a disorder resulting from genetic mutations in the Factor 9 gene (F9). Genotyping of HB patients is important for genetic counseling and patient management. Here we report a study of mutations identified in a large sample of HB patients in the US. Patients were enrolled through an inhibitor surveillance study at 17 hemophilia treatment centers (HTCs). A total of 87 unique mutations were identified from 225 of the 226 patients, including deletions, insertions, and point mutations. Point mutations were distributed throughout the F9 gene and were found in 86% of the patients. Of these mutations, 24 were recurrent in the population, and 3 of them (c.316G>A, c.1025C>T and c.1328T>A) accounted for 84 patients (37.1%). Haplotype analysis revealed that the high recurrence arose from a founder effect. The severity of HB was found to correlate with the type of mutation. Inhibitors developed only in severe cases with large deletions and nonsense mutations. None of the mild or moderate patients developed inhibitors. Our results provide a resource describing F9 mutations in US HB patients and confirm previous findings that patients bearing large deletions and nonsense mutations are at high risk of developing inhibitors.

Silent cerebral infarct (SCI) is the most commonly recognized cause of neurological injury in sickle cell anaemia (SCA). We tested the hypothesis that magnetic resonance angiography (MRA)-defined vasculopathy is associated with SCI. Furthermore, we examined genetic variations in glucose-6-phosphate dehydrogenase (G6PD) and HBA (alpha-globin) genes to determine their association with intracranial vasculopathy in children with SCA. Magnetic resonance imaging (MRI) of the brain and MRA of the cerebral vasculature were available in 516 paediatric patients with SCA, enrolled in the Silent Infarct Transfusion (SIT) Trial. All patients were screened for G6PD mutations and HBA deletions. SCI were present in 41.5% (214 of 516) of SIT Trial children. The frequency of intracranial vasculopathy with and without SCI was 15.9% and 6.3%, respectively (P < 0.001). Using a multivariable logistic regression model, only the presence of a SCI was associated with increased odds of vasculopathy (P = 0.0007, odds ratio (OR) 2.84; 95% Confidence Interval (CI) = 1.55-5.21). Among male children with SCA, G6PD status was associated with vasculopathy (P = 0.04, OR 2.78; 95% CI = 1.04-7.42), while no significant association was noted for HBA deletions. Intracranial vasculopathy was observed in a minority of children with SCA, and when present, was associated with G6PD status in males and SCI.

Sickle cell disease (SCD) is a common hemolytic disorder with a broad range of complications, including vaso-occlusive episodes, acute chest syndrome (ACS), pain, and stroke. Heme oxygenase-1 (gene HMOX1; protein HO-1) is the inducible, rate-limiting enzyme in the catabolism of heme and might attenuate the severity of outcomes from vaso-occlusive and hemolytic crises. A (GT)(n) dinucleotide repeat located in the promoter region of the HMOX1 gene is highly polymorphic, with long repeat lengths linked to decreased activity and inducibility. We examined this polymorphism to test the hypothesis that short alleles are associated with a decreased risk of adverse outcomes (hospitalization for pain or ACS) among a cohort of 942 children with SCD. Allele lengths varied from 13 to 45 repeats and showed a trimodal distribution. Compared with children with longer allele lengths, children with two shorter alleles (4%; ≤25 repeats) had lower rates of hospitalization for ACS (incidence rate ratio 0.28, 95% confidence interval: 0.10-0.81), after adjusting for sex, age, asthma, percentage of fetal hemoglobin and alpha-globin gene deletion. No relationship was identified between allele lengths and pain rate. We provide evidence that genetic variation in HMOX1 is associated with decreased rates of hospitalization for ACS, but not pain. This study is registered at www.ClinicalTrails.gov (NCT00072761).

Both genetic and treatment-related risk factors contribute to the development of inhibitors in haemophilia. An inhibitor surveillance system piloted at 12 US sites has the goal of assessing risk factors through prospective data collection. This report examines the relationship of genotype and race/ethnicity to history of inhibitor in a large cohort of US haemophilia patients. Mutation analysis was performed on 676 haemophilia A (HA) and 153 haemophilia B (HB) patients by sequencing, Multiplex Ligation-dependent Probe Amplification, and PCR for inversions in F8 introns 22 (inv22) and 1 (inv1). Two HB patients with deletions had history of inhibitor. In severe HA, frequency of history of inhibitor was: large deletion 57.1%, splice site 35.7%, inv22 26.8%, nonsense 24.5%, frameshift 12.9%, inv1 11.1% and missense 9.5%. In HA, 19.6% of 321 White non-Hispanics (Whites), 37.1% of 35 Black non-Hispanics (Blacks) and 46.9% of 32 Hispanics had history of inhibitor (P = 0.0003). Mutation types and novel mutation rates were similar across ethnicities. When F8 haplotypes were constructed, Whites and Hispanics showed only H1 and H2. Within H1, history of inhibitor was 12.4% in Whites, 40.0% in Blacks (P = 0.009) and 32.4% in Hispanics (P = 0.002). Inhibitor frequency is confirmed to vary by mutation type and race in a large US population. White patients with history of inhibitor did not exhibit rare F8 haplotypes. F8 gene analysis did not reveal a cause for the higher inhibitor frequencies in Black and Hispanic patients.