Genotyping patients with recent blood transfusions

Leveraging clinical decision support to reduce the risk of discordant pharmacogenomics results

Pharmacogenomics (PGx) testing is commonly utilized to predict a patient's response to medications based on the presence of genetic variants. However, certain conditions have been associated with potentially inaccurate PGx results. The majority of medications are predominantly metabolized in the liver; therefore, in the case of liver transplantation, PGx results may be misinterpreted in the context of drug-metabolizing enzymes. Other instances of ambiguous PGx results have been reported in the literature in conditions such as allogeneic stem cell or bone marrow transplant, chronic lymphocytic leukemia, acute or chronic myeloid leukemia and blood transfusion. In order to prevent potential inaccuracies in PGx testing, Sanford Imagenetics developed an active, interruptive alert to inform providers of the potential for inaccurate PGx results.

Does Transfusion of Red Blood Cells Impact Germline Genetic Test Results?

Purpose: molecular testing is often indicated for recently transfused patients. However, there are no guidelines regarding the potential interference from donor DNA or whether it is necessary to wait for a period of time post-transfusion prior to genetic testing. While the majority of patients are transfused in the non-trauma setting using leukoreduced (LR) red blood cell products, the degree of leukoreduction varies among centers and is not universally practiced. Methods: whole blood units collected from anonymous donors were used in an in vitro transfusion model. One unit was split: half being leukoreduced simulating a leukopenic recipient and half left untreated. Donors were simulated by leukoreduced, partially leukoreduced (PLR), or non-leukoreduced units, transfused in 2, 5, or 16 unit equivalents. DNA from the combinations were subjected to short tandem repeat (STR) analysis for chimerism detection. Results: donor DNA was not detectable in any of the LR combinations, but detected in the PLR combinations, ranging from 0.1 to 1.5% donor DNA in the immunocompetent recipient and 6.3–27.8% in the leukopenic recipient. Non-LR donor DNA was also detected (13–95%). Conclusion: donor-derived DNA from leukoreduced blood products is unlikely to interfere with the interpretation of germline genetic testing in immunocompetent recipients but may interfere in immunocompromised recipients.

Pitfalls and caveats in α1-antitrypsin deficiency testing: a guide for clinicians

α1-antitrypsin deficiency (AATD) remains the only readily identified genetic cause of chronic obstructive pulmonary disease (COPD). Furthermore, there is growing evidence that even a moderate deficiency increases the risk of lung disease among smokers. Despite these facts, the uptake of testing for AATD in at-risk populations remains low for many reasons, and a lack of clarity among clinicians regarding the most appropriate diagnostic techniques presents a major deterrent. This Personal View addresses the benefits of diagnosis, the technical basis of the available diagnostic methods, and possible clinical confounders for each test. We include a series of unusual cases encountered at our National Centre of Expertise to provide context. The topics covered should equip clinicians with the core knowledge required to confidently assess patients for AATD.

Comparison of Phenotypic Activated Protein C Resistance Testing With a Genetic Assay for Factor V Leiden

Objectives

To compare the accuracy and reliability of phenotypic activated protein C resistance (aPC-R) assays with a genotypic assay for the factor V Leiden F5 p.R506Q (FVL) mutation.

Methods

Data were obtained from an electronic data warehouse for FVL testing performed at an academic institution with a large referral laboratory service. In total, 1,596 patients were identified who had undergone both phenotypic aPC-R and genotypic FVL mutation testing.

Results

Phenotypic testing showed a high level of sensitivity, specificity, and other biostatistical values compared with genotypic testing. Improvements in technology decreased the amount of equivocal phenotypic results.

Conclusions

Phenotypic assays had close to total concordance with genotypic assays over 16 years of testing. Changing ordering practices could result in up to an 80% reduction in testing costs.

Matrix and backstage: cellular substrates for viral vaccines

Vaccines are complex products that are manufactured in highly dynamic processes. Cellular substrates are one critical component that can have an enormous impact on reactogenicity of the final preparation, level of attenuation of a live virus, yield of infectious units or antigens, and cost per vaccine dose. Such parameters contribute to feasibility and affordability of vaccine programs both in industrialized countries and developing regions. This review summarizes the diversity of cellular substrates for propagation of viral vaccines from primary tissue explants and embryonated chicken eggs to designed continuous cell lines of human and avian origin.

Circulating mitochondrial DNA in patients in the ICU as a marker of mortality: derivation and validation

BACKGROUND

Mitochondrial DNA (mtDNA) is a critical activator of inflammation and the innate immune system. However, mtDNA level has not been tested for its role as a biomarker in the intensive care unit (ICU). We hypothesized that circulating cell-free mtDNA levels would be associated with mortality and improve risk prediction in ICU patients.

METHODS AND FINDINGS

Analyses of mtDNA levels were performed on blood samples obtained from two prospective observational cohort studies of ICU patients (the Brigham and Women's Hospital Registry of Critical Illness [BWH RoCI, n = 200] and Molecular Epidemiology of Acute Respiratory Distress Syndrome [ME ARDS, n = 243]). mtDNA levels in plasma were assessed by measuring the copy number of the NADH dehydrogenase 1 gene using quantitative real-time PCR. Medical ICU patients with an elevated mtDNA level (≥3,200 copies/µl plasma) had increased odds of dying within 28 d of ICU admission in both the BWH RoCI (odds ratio [OR] 7.5, 95% CI 3.6-15.8, p = 1×10(-7)) and ME ARDS (OR 8.4, 95% CI 2.9-24.2, p = 9×10(-5)) cohorts, while no evidence for association was noted in non-medical ICU patients. The addition of an elevated mtDNA level improved the net reclassification index (NRI) of 28-d mortality among medical ICU patients when added to clinical models in both the BWH RoCI (NRI 79%, standard error 14%, p<1×10(-4)) and ME ARDS (NRI 55%, standard error 20%, p = 0.007) cohorts. In the BWH RoCI cohort, those with an elevated mtDNA level had an increased risk of death, even in analyses limited to patients with sepsis or acute respiratory distress syndrome. Study limitations include the lack of data elucidating the concise pathological roles of mtDNA in the patients, and the limited numbers of measurements for some of biomarkers.

CONCLUSIONS

Increased mtDNA levels are associated with ICU mortality, and inclusion of mtDNA level improves risk prediction in medical ICU patients. Our data suggest that mtDNA could serve as a viable plasma biomarker in medical ICU patients.

ABCA3 deficiency: neonatal respiratory failure and interstitial lung disease

ABCA3 is a member of the ATP Binding Cassette family of proteins, transporters that hydrolyze ATP in order to move substrates across biological membranes. Mutations in the gene encoding ABCA3 have been found in children with severe neonatal respiratory disease and older children with some forms of interstitial lung disease. This review summarizes current knowledge concerning clinical, genetic, and pathologic features of the lung disease associated with mutations in the ABCA3 gene, and also briefly reviews some other forms of childhood interstitial lung diseases that have their antecedents in the neonatal period and may also have a genetic basis.

Can post-mortem blood be used for DNA profiling after peri-mortem blood transfusion?

The question of whether blood transfusions can affect DNA profiling is still a contentious issue throughout the forensic community. It is hypothesised that donor leucocytes present in the administered blood will be detected upon examination of recipient blood. In order to resolve this issue, a selection of theoretical experiments were carried out to determine how much donor DNA must be present for its detection in blood components. Five casework examples of material collected from individuals after massive transfusion, including a case of whole organ transplantation, were also investigated. The results indicated that filtration processes used during blood production do not allow the passage of enough donor leucocytes for detection using current forensic profiling techniques. No evidence of secondary profile alleles were found in any case, indicating that peri-mortem blood transfusion does not affect DNA profiling.

Clinical predictors of and mortality in acute respiratory distress syndrome: Potential role of red cell transfusion*

OBJECTIVE

Clinical predictors for acute respiratory distress syndrome (ARDS) have been studied in few prospective studies. Although transfusions are common in the intensive care unit, the role of submassive transfusion in non-trauma-related ARDS has not been studied. We describe here the clinical predictors of ARDS risk and mortality including the role of red cell transfusion.

DESIGN

Observational prospective cohort.

SETTING

Intensive care unit of Massachusetts General Hospital.

PATIENTS

We studied 688 patients with sepsis, trauma, aspiration, and hypertransfusion.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Two hundred twenty-one (32%) subjects developed ARDS with a 60-day mortality rate of 46%. Significant predictors for ARDS on multivariate analyses included trauma (adjusted odds ratio [ORadj] 0.22, 95% confidence interval [CI] 0.09-0.53), diabetes (ORadj 0.58, 95% CI 0.36-0.92), direct pulmonary injury (ORadj 3.78, 95% CI 2.45-5.81), hematologic failure (ORadj 1.84, 95% CI 1.05-3.21), transfer from another hospital (ORadj 2.08, 95% CI 1.33-3.25), respiratory rate >33 breaths/min (ORadj 2.39, 95% CI 1.51-3.78), hematocrit >37.5% (ORadj 1.77, 95% CI 1.14-2.77), arterial pH <7.33 (ORadj 2.00, 95% CI 1.31-3.05), and albumin </=2.3 g/dL (ORadj 1.80, 95% CI 1.18-2.73). Packed red blood cell transfusion was associated with ARDS (ORadj 1.52, 95% CI 1.00-2.31, p = .05). Significant predictors for mortality in ARDS included age (ORadj 1.96, 95% CI 1.50-2.53), Acute Physiology and Chronic Health Evaluation III score (ORadj 1.78, 95% CI 1.16-2.73), trauma (ORadj 0.075, 95% CI 0.006-0.96), corticosteroids before ARDS (ORadj 4.65, 95% CI 1.47-14.7), and arterial pH <7.22 (ORadj 2.32, 95% CI 1.02-5.25). Packed red blood cell transfusions were associated with increased mortality in ARDS (ORadj 1.10 per unit transfused; 95% CI 1.04-1.17) with a significant dose-dependent response (p = .02).

CONCLUSIONS

Important predictors for the development of and mortality in ARDS were identified. Packed red blood cell transfusion was associated with an increased development of and increased mortality in ARDS.