Utilization of Leads After Permanent Implant in Spinal Cord Stimulator Systems.

OBJECTIVE: The goal of this study was to determine the frequency and clinical indications associated with implantation of single vs. dual percutaneous lead spinal cord stimulator (SCS) systems and to look further into how these leads are utilized for treatment. MATERIALS AND METHODS: A retrospective cohort analysis of all patients undergoing SCS implantation between January 2001 and December 2013 with a minimum of 2 years of clinical follow-up was performed. Number of trial leads and implanted leads was recorded. For patients with dual-lead systems, it was noted if and when the second lead was used, along with the clinical indication for lead activation. RESULTS: In the 259-patient cohort, 15.8% (n = 41) patients underwent placement of a single-lead system, 83.0% (n = 215) underwent placement of a dual-lead system, and 1.2% (n = 3) underwent placement of 3-lead systems. Placement of dual-lead systems was similar among all indication groups. Of those patients with a dual-lead system in place, 88.1% utilized both leads and average time to programming of the second lead was 2.3 months. The most common reason to activate the second lead was inadequate stimulation coverage. Five of the 41 patients with single-lead systems underwent an additional surgery to implant a second lead due to inadequate stimulation with 1 lead. CONCLUSIONS: To our knowledge this is the first descriptive analysis of the frequency of single- and dual-lead SCS systems. This report indicates that dual-lead systems are most often placed and both leads are required for optimal patient therapy.

Deep procedural sedation by a sedationist team for outpatient pediatric renal biopsies.

To date, no study has analyzed the use of deep PS for pediatric renal biopsies by a dedicated sedation team in an outpatient setting. Retrospective analysis of renal biopsies performed at CHOA from 2009 to 2013. Patient demographics, procedure success, and sedation-related events were analyzed. Logistic regression techniques were applied to identify characteristics associated with procedure safety and success. A total of 174 biopsies from 136 patients, aged 2-21 yr, were reviewed. Of the 174 biopsies, 63 of 174 (36%) were from native, and 111 of 174 (64%) were from transplanted kidneys, respectively. No deaths, allograft losses, or unanticipated hospital admissions occurred. The most commonly utilized interventions during sedation were blow-by oxygen (29.9%) and CPAP (12.1%). Children receiving the combination of F + P had significantly higher biopsy success rates vs. other drug combinations (96.1% vs. 79%; p = 0.014). There was no difference in complication rates regardless of drug combination or biopsy type (transplanted vs. native). The combination of F + P yields a high procedural success rate for outpatient native and transplanted kidney biopsies. We identified a number of sedation-related events that can be easily managed by a well-trained sedationist team.

Patient Outcomes and Spinal Cord Stimulation: A Retrospective Case Series Evaluating Patient Satisfaction, Pain Scores, and Opioid Requirements.

INTRODUCTION: Spinal cord stimulators (SCS) are used to treat various chronic pain states. Establishing patient outcomes in terms of pain control, opioid medication use, and overall satisfaction is vital in maintaining SCS's role in clinical practice. METHODS: All patients who underwent SCS implantation between January 2001 and December 2011 at a tertiary academic pain medicine center were included if he or she underwent permanent cervical or thoracolumbar dorsal column SCS implantation and age was 18 or greater. For the 199 patients who met inclusion criteria, data were collected retrospectively. Preimplant information included indication for implantation, Numeric Rating Scale (NRS) score, and dose in oral morphine equivalents (OME). Postimplant NRS score was recorded at 6 months and 1 year. OME requirement and patient satisfaction were determined at 1 year postimplantation. RESULTS: This data set showed an overall decrease in OME requirements and NRS scores at both 6 months and 1 year. These differences were statistically significant (P < 0.01) compared to preimplantation values. Additionally, 84.27% of patients were satisfied with their implants at 1 year. Patient outcomes were analyzed further in respect to implant indication; groups included failed back surgery syndrome (FBSS), complex regional pain syndrome (CRPS), angina, and other. For all groups, there were statistically significant (P < 0.01) decreases in NRS scores at 6 months and 1 year. In the FBSS and CRPS groups, statistically significant (P < 0.02) decreases in OME usage existed. CONCLUSION: Retrospective review of patients with spinal cord stimulators revealed OME reduction at 1 year for those patients in the FBSS and CRPS groups; patient satisfaction at 1 year and NRS score reduction at 6 months and 1 year were statistically significant for all groups.

UDP-galactose 4'-epimerase activities toward UDP-Gal and UDP-GalNAc play different roles in the development of Drosophila melanogaster.

In both humans and Drosophila melanogaster, UDP-galactose 4'-epimerase (GALE) catalyzes two distinct reactions, interconverting UDP-galactose (UDP-gal) and UDP-glucose (UDP-glc) in the final step of the Leloir pathway of galactose metabolism, and also interconverting UDP-N-acetylgalactosamine (UDP-galNAc) and UDP-N-acetylglucosamine (UDP-glcNAc). All four of these UDP-sugars serve as vital substrates for glycosylation in metazoans. Partial loss of GALE in humans results in the spectrum disorder epimerase deficiency galactosemia; partial loss of GALE in Drosophila melanogaster also results in galactose-sensitivity, and complete loss in Drosophila is embryonic lethal. However, whether these outcomes in both humans and flies result from loss of one GALE activity, the other, or both has remained unknown. To address this question, we uncoupled the two activities in a Drosophila model, effectively replacing the endogenous dGALE with prokaryotic transgenes, one of which (Escherichia coli GALE) efficiently interconverts only UDP-gal/UDP-glc, and the other of which (Plesiomonas shigelloides wbgU) efficiently interconverts only UDP-galNAc/UDP-glcNAc. Our results demonstrate that both UDP-gal and UDP-galNAc activities of dGALE are required for Drosophila survival, although distinct roles for each activity can be seen in specific windows of developmental time or in response to a galactose challenge. By extension, these data also suggest that both activities might play distinct and essential roles in humans.

Spinal cord stimulator explantation for magnetic resonance imaging: a case series.

INTRODUCTION: Spinal cord stimulator (SCS) systems are implanted to treat pain conditions such as neuropathic, radicular, and ischemic pain syndromes. Prior to July 2013, SCS systems were not magnetic resonance imaging (MRI) compatible due to the risk of thermal injury at the site of the leads and generator. Although there are some case reports of patients undergoing MRI studies with SCS systems in place, these stimulators are frequently explanted when clinical care has necessitated an MRI. The purpose of this case series is to discuss the role of SCS explantation in order to acquire an MRI. METHODS: This study was performed at a tertiary academic pain medicine clinic. After exempt status was obtained via the institutional review board, patients were identified via the use of Common Procedural Terminology codes for implantable devices. A chart review was performed to identify all patients >18 years of age who had a lumbar or thoracic dorsal column SCS implanted during January 2001-December 2011. The charts were then followed to identify any patients who underwent a surgery for explantation of the device. Data collection included the total number of patients undergoing permanent SCS implantation, the total number of explantation of these devices, patient demographic factors, indication for SCS implantation, incidence of revisions and the indication, duration between implantation and explant of the device, and indication for explantation. RESULTS: During the time between 2001 and 2011, 199 patients were identified who underwent a thoracic or lumbar SCS implant after a successful trial. Among 199 implants, 33 devices were explanted, and of these, four were explanted due to the primary need for an MRI scan.

Recombinant antibodies encoded by IGHV1-69 react with pUL32, a phosphoprotein of cytomegalovirus and B-cell superantigen.

Leukemia cells from patients with chronic lymphocytic leukemia (CLL) express a highly restricted immunoglobulin heavy variable chain (IGHV) repertoire, suggesting that a limited set of antigens reacts with leukemic cells. Here, we evaluated the reactivity of a panel of different CLL recombinant antibodies (rAbs) encoded by the most commonly expressed IGHV genes with a panel of selected viral and bacterial pathogens. Six different CLL rAbs encoded by IGHV1-69 or IGHV3-21, but not a CLL rAb encoded by IGHV4-39 genes, reacted with a single protein of human cytomegalovirus (CMV). The CMV protein was identified as the large structural phosphoprotein pUL32. In contrast, none of the CLL rAbs bound to any other structure of CMV, adenovirus serotype 2, Salmonella enterica serovar Typhimurium, or of cells used for propagation of these microorganisms. Monoclonal antibodies or humanized rAbs of irrelevant specificity to pUL32 did not react with any of the proteins present in the different lysates. Still, rAbs encoded by a germ line IGHV1-69 51p1 allele from CMV-seropositive and -negative adults also reacted with pUL32. The observed reactivity of multiple different CLL rAbs and natural antibodies from CMV-seronegative adults with pUL32 is consistent with the properties of a superantigen.

Novel apatite-based sorbent for defluoridation: synthesis and sorption characteristics of nano-micro-crystalline hydroxyapatite-coated-limestone.

Elevated levels of fluoride (F(-)) in groundwaters of granitic and basaltic terrains pose a major environmental problem and are affecting millions of people all over the world. Hydroxyapatite (HA) has been shown to be a strong sorbent for F(-); however, low permeability of synthetic HA results in poor sorption efficiency. Here we provide a novel method of synthesizing nano- to micrometer sized HA on the surfaces of granular limestone to improve the sorption efficiency of the HA-based filter. Our experiments with granular limestone (38-63, 125-500 µm) and dissolved PO4(3-) (0.5-5.3 mM) as a function of pH (6-8) and temperature (25-80 °C) indicated rapid formation of nano- to micrometer sized HA crystals on granular limestone with the maximum surface coverage at lower pH and in the presence of multiple additions of aqueous PO4(3-). The HA crystal morphology varied with the above variables. The sorption kinetics and magnitude of F(-) sorption by HA-coated-fine limestone are comparable to those of pure HA, and the F(-) levels dropped to below the World Health Organization's drinking water limit of 79 µM for F(-) concentrations commonly encountered in contaminated potable waters, suggesting that these materials could be used as effective filters. Fluorine XANES spectra of synthetic HA reacted with F(-) suggest that the mode of sorption is through the formation of fluoridated-HA or fluorapatite at low F(-) levels and fluorite at high F(-) loadings.

Considerations for accurate gene expression measurement by reverse transcription quantitative PCR when analysing clinical samples.

Reverse transcription quantitative PCR is an established, simple and effective method for RNA measurement. However, technical standardisation challenges combined with frequent insufficient experimental detail render replication of many published findings challenging. Consequently, without adequate consideration of experimental standardisation, such findings may be sufficient for a given publication but cannot be translated to wider clinical application. This article builds on earlier standardisation work and the MIQE guidelines, discussing processes that need consideration for accurate, reproducible analysis when dealing with patient samples. By applying considerations common to the science of measurement (metrology), one can maximise the impact of gene expression studies, increasing the likelihood of their translation to clinical tools.

Application of next generation qPCR and sequencing platforms to mRNA biomarker analysis.

Recent years have seen the emergence of new high-throughput PCR and sequencing platforms with the potential to bring analysis of transcriptional biomarkers to a broader range of clinical applications and to provide increasing depth to our understanding of the transcriptome. We present an overview of how to process clinical samples for RNA biomarker analysis in terms of RNA extraction and mRNA enrichment, and guidelines for sample analysis by RT-qPCR and digital PCR using nanofluidic real-time PCR platforms. The options for quantitative gene expression profiling and whole transcriptome sequencing by next generation sequencing are reviewed alongside the bioinformatic considerations for these approaches. Considering the diverse technologies now available for transcriptome analysis, methods for standardising measurements between platforms will be paramount if their diagnostic impact is to be maximised. Therefore, the use of RNA standards and other reference materials is also discussed.

Proceedings of the annual meeting of the European Consortium of Lipodystrophies (ECLip), Pisa, Italy, 28-29 September 2023.

Lipodystrophy syndromes are rare diseases primarily affecting the development or maintenance of the adipose tissue but are also distressing indirectly multiple organs and tissues, often leading to reduced life expectancy and quality of life. Lipodystrophy syndromes are multifaceted disorders caused by genetic mutations or autoimmunity in the vast majority of cases. While many subtypes are now recognized and classified, the disease remains remarkably underdiagnosed. The European Consortium of Lipodystrophies (ECLip) was founded in 2014 as a non-profit network of European centers of excellence working in the field of lipodystrophies aiming at promoting international collaborations to increase basic scientific understanding and clinical management of these syndromes. The network has developed a European Patient Registry as a collaborative research platform for consortium members. ECLip and ECLip registry activities involve patient advocacy groups to increase public awareness and to seek advice on research activities relevant from the patients perspective. The annual ECLip congress provides updates on the research results of various network groups members.

A mutation deleting sequences encoding the amino terminus of human cytomegalovirus UL84 impairs interaction with UL44 and capsid localization.

Protein-protein interactions are required for many biological functions. Previous work has demonstrated an interaction between the human cytomegalovirus DNA polymerase subunit UL44 and the viral replication factor UL84. In this study, glutathione S-transferase pulldown assays indicated that residues 1 to 68 of UL84 are both necessary and sufficient for efficient interaction of UL84 with UL44 in vitro. We created a mutant virus in which sequences encoding these residues were deleted. This mutant displayed decreased virus replication compared to wild-type virus. Immunoprecipitation assays showed that the mutation decreased but did not abrogate association of UL84 with UL44 in infected cell lysate, suggesting that the association in the infected cell can involve other protein-protein interactions. Further immunoprecipitation assays indicated that IRS1, TRS1, and nucleolin are candidates for such interactions in infected cells. Quantitative real-time PCR analysis of viral DNA indicated that the absence of the UL84 amino terminus does not notably affect viral DNA synthesis. Western blotting experiments and pulse labeling of infected cells with [(35)S]methionine demonstrated a rather modest downregulation of levels of multiple proteins and particularly decreased levels of the minor capsid protein UL85. Electron microscopy demonstrated that viral capsids assemble but are mislocalized in nuclei of cells infected with the mutant virus, with fewer cytoplasmic capsids detected. In sum, deletion of the sequences encoding the amino terminus of UL84 affects interaction with UL44 and virus replication unexpectedly, not viral DNA synthesis. Mislocalization of viral capsids in infected cell nuclei likely contributes to the observed decrease in virus replication.

A phase II study of DAS181, a novel host directed antiviral for the treatment of influenza infection.

BACKGROUND: DAS181, a novel host-directed antiviral in development for influenza treatment, was assessed in this phase II clinical trial. METHODS: This study was a double-blind, placebo-controlled phase II clinical trial assessing influenza viral load and patient safety in otherwise healthy influenza-infected participants. Participants were randomized to a single-dose, multiple-dose, or placebo group and were followed for safety and virologic outcomes. RESULTS: A total of 177 laboratory-confirmed influenza-infected participants were enrolled in the trial, which encompassed 3 influenza seasons from 2009-2011 in both the Northern and Southern Hemispheres. Thirty-seven percent of participants had confirmed infection with influenza B, 33% with seasonal H3N2, 29% with pandemic 2009 H1N1, and 1 participant was positive for both influenza B and pandemic 2009 H1N1. Significant effects were observed in regard to decreased change from baseline viral load and viral shedding in the multiple-dose group compared with placebo as measured by quantitative polymerase chain reaction (P < .05). No instances of H274Y were observed among viral isolates from this trial. Overall, the drug was generally well tolerated. CONCLUSIONS: DAS181 significantly reduced viral load in participants infected with influenza, thus warranting future clinical development of this novel host-directed therapy. CLINICAL TRIALS.GOV IDENTIFIER: NCT01037205.

Defects in lamin B1 expression or processing affect interphase chromosome position and gene expression.

Radial organization of nuclei with peripheral gene-poor chromosomes and central gene-rich chromosomes is common and could depend on the nuclear boundary as a scaffold or position marker. To test this, we studied the role of the ubiquitous nuclear envelope (NE) component lamin B1 in NE stability, chromosome territory position, and gene expression. The stability of the lamin B1 lamina is dependent on lamin endoproteolysis (by Rce1) but not carboxymethylation (by Icmt), whereas lamin C lamina stability is not affected by the loss of full-length lamin B1 or its processing. Comparison of wild-type murine fibroblasts with fibroblasts lacking full-length lamin B1, or defective in CAAX processing, identified genes that depend on a stable processed lamin B1 lamina for normal expression. We also demonstrate that the position of mouse chromosome 18 but not 19 is dependent on such a stable nuclear lamina. The results implicate processed lamin B1 in the control of gene expression as well as chromosome position.

Towards a predictive model of COVID-19 vaccine hesitancy among American adults.

Designing effective public health campaigns to combat COVID-19 vaccine hesitancy requires an understanding of i) who the vaccine hesitant population is, and ii) the determinants of said population's hesitancy. While researchers have identified a number of variables associated with COVID-19 vaccine hesitancy that could inform such campaigns, little is known about the cumulative or relative predictive power of these factors. In this article, we employ a machine learning model to analyze online survey data collected from 3353 respondents. The model incorporates an array of variables that have been shown to impact vaccine hesitancy, allowing us to i) test how well we can predict vaccine hesitancy, and ii) compare the relative predictive impact of each covariate. The model allows us to correctly classify individuals that are vaccine acceptant with 97% accuracy, and those that are vaccine hesitant with 72% accuracy. Trust in and knowledge about vaccines is, by far, the strongest predictor of vaccination choice. While our results demonstrate that public health campaigns designed to increase vaccination rates must find a way to increase public trust in COVID-19 vaccines, our results cannot speak to the malleability of such beliefs, nor how to enhance trust.

Assessment of inequity in bicyclist crashes using bivariate Bayesian copulas.

INTRODUCTION: Physical activity associated with active transport modes such as bicycling has major health benefits and can help to reduce health concerns related to sedentary lifestyles, such as cardiovascular disease, Type II diabetes, and obesity, as well as risks of colon and breast cancer, high blood pressure, lipid disorders, osteoporosis, depression, and anxiety. However, as a vulnerable user group, bicyclists experience negative health impacts of transportation policies and infrastructure, such as traffic crashes and exposure to air and noise pollution that is disproportionately distributed within low-income and underserved areas. METHOD: This study used aggregated (block-group) bicyclist crash data from Harris County, Texas, to analyze how various equity measures are associated with both fatal and injury (FI) and no injury (property damage only) bicyclist crashes that occurred from 2010 to 2017. We used Bayesian bivariate copula-based random effects regression analysis to evaluate these associations. In contrast to more traditional univariate analysis, this novel methodology can consider the effects of factors of interest across different severity levels or crash types to fully understand their effects and how they may differ across categories. RESULTS: The analysis results indicate that the bicyclist exposure, vehicle exposure, population demographics, population density, the percentage of African-Americans, and households below the poverty level are associated with both FI and PDO bicyclist crashes. CONCLUSIONS: Although more location and context-specific analyses are required, this study's overall results once again conform with the findings and assumptions in bicycling safety literature that the low-income and racially diverse communities are prone to experience more bicyclist crashes. PRACTICAL APPLICATIONS: The findings of this study may have implications for future transportation and planning policies. These findings can be used to guide the policies and strategies targeting the elimination of inequity in transportation-related health concerns.

Effect of Exhausted Coffee Ground Particle Size on Metal Ion Adsorption Rates and Capacities.

Spent coffee grounds (SCGs) are common waste products that can be used as low-cost adsorbents to remove contaminants from water. SCGs come in a range of particle sizes based on how they were ground to brew coffee. However, few studies have investigated how SCG particle size influences the adsorption rate and capacities of metal ions. In this study, SCGs were washed under alkaline conditions, creating exhausted coffee grounds (ECGs). ECGs were sieved into four particle size ranges (106-300, 300-500, 500-710, and 710-1000 µm). Monocomponent batch adsorption experiments were conducted with each size fraction using 0.3 mM Pb2+, Cu2+, Zn2+, and Ni2+ at pH 5.5 to examine the effect of particle size on the adsorption rates and capacities. The initial adsorption rates for all the four metal ions were 8-12 times higher for the smallest ECGs compared to the largest ECGs. Slower initial adsorption rates with increasing particle size were due to intraparticle diffusion of metal ions into the porous structure of ECGs. However, the equilibrium adsorption capacities for each metal ion and the surface acidic group concentrations were similar across the range of particle sizes studied, suggesting that grinding ECGs does not substantially change the number of adsorption sites. The equilibrium adsorption capacities for Cu2+ and Pb2+ were 0.18 and 0.17 mmol g-1, respectively. Zn2+ and Ni2+ had lower adsorption capacities of 0.12 and 0.10 mmol g-1, respectively. The time needed to reach equilibrium ranged from less than 2 h for Zn2+ and Ni2+ adsorption onto the smallest ECGs to several hours for Pb2+ or Cu2+ adsorption onto the largest ECGs. Future adsorption studies should consider the effect of ECG particle size on reported adsorption capacities, particularly for shorter experiments that have not yet reached equilibrium.

Preparing for a Career in Pediatric Hospital Medicine: A Needs Assessment and Recommendations for Individualized Curricula.

OBJECTIVES: The individualized curriculum within residency programs allows residents to tailor their elective time toward future career goals and interests. Our objective was to identify experiences and activities that would foster resident interest and enhance preparation for a career in pediatric hospital medicine (PHM). METHODS: Electronic surveys were distributed to pediatric hospitalists, PHM fellowship directors, and graduating PHM fellows. These stakeholders were asked to identify key experiences for residents to explore before entering fellowship or practice. Descriptive statistics and thematic analysis were performed on survey responses. RESULTS: Forty-six percent of PHM fellows (16 of 35), 42% of pediatric hospitalists (149 of 356), and 58% of fellowship program directors (35 of 60) completed the survey. All 3 groups identified complex care as the most important clinical experience to gain in residency. Other highly valued clinical experiences included pain management, surgical comanagement, and palliative care. Lumbar puncture, electrocardiograph interpretation, and airway management were identified as essential procedural skills. Nonclinical experiences that were deemed important included quality improvement, development of teaching skills, and research methodology. All groups agreed that these recommendations should be supplemented with effective mentorship. CONCLUSIONS: Identification of key clinical experiences, nonclinical activities, and mentorship for residents interested in PHM may assist with tailoring the individualized curriculum to personal career goals. Incorporating these suggested experiences can improve preparedness of residents entering PHM.

Proceedings of the annual meeting of the European Consortium of Lipodystrophies (ECLip) Cambridge, UK, 7-8 April 2022.

Lipodystrophy syndromes are rare diseases with defects in the development or maintenance of adipose tissue, frequently leading to severe metabolic complications. They may be genetic or acquired, with variable clinical forms, and are largely underdiagnosed. The European Consortium of Lipodystrophies, ECLip, is a fully functional non-profit network of European centers of excellence working in the field of lipodystrophies. It provides a favorable environment to promote large Europe-wide and international collaborations to increase the basic scientific understanding and clinical management of these diseases. It works with patient advocacy groups to increase public awareness. The network also promotes a European Patient Registry of lipodystrophies, as a collaborative research platform for consortium members. The annual congress organized gives an update of the findings of network research groups, highlighting clinical and fundamental aspects. The talks presented during the meeting in Cambridge, UK, in 2022 are summarized in these minutes.

Treatment of parainfluenza 3 infection with DAS181 in a patient after allogeneic stem cell transplantation.

Parainfluenza virus (PIV) can cause significant morbidity after allogeneic stem cell transplantation (SCT). We report the first use of inhaled DAS181 for PIV in an allogeneic SCT recipient. Symptoms, oxygenation, and pulmonary function tests improved. Nasopharyngeal samples showed a reduction in viral load. DAS181 should be systematically evaluated for severe PIV infection.

Origins, distribution and expression of the Duarte-2 (D2) allele of galactose-1-phosphate uridylyltransferase.

Duarte galactosemia is a mild to asymptomatic condition that results from partial impairment of galactose-1-phosphate uridylyltransferase (GALT). Patients with Duarte galactosemia demonstrate reduced GALT activity and carry one profoundly impaired GALT allele (G) along with a second, partially impaired GALT allele (Duarte-2, D2). Molecular studies reveal at least five sequence changes on D2 alleles: a p.N314D missense substitution, three intronic base changes and a 4 bp deletion in the 5' proximal sequence. The four non-coding sequence changes are unique to D2. The p.N314D substitution, however, is not; it is found together with a silent polymorphism, p.L218(TTA), on functionally normal Duarte-1 alleles (D1, also called Los Angeles or LA alleles). The HapMap database reveals that p.N314D is a common human variant, and cross-species comparisons implicate D314 as the ancestral allele. The p.N314D substitution is also functionally neutral in mammalian cell and yeast expression studies. In contrast, the 4 bp 5' deletion characteristic of D2 alleles appears to be functionally impaired in reporter gene transfection studies. Here we present allele-specific qRT-PCR evidence that D2 alleles express less mRNA in vivo than their wild-type counterparts; the difference is small but statistically significant. Furthermore, we characterize the prevalence of the 4 bp deletion in GG, NN and DG populations; the deletion appears exclusive to D2 alleles. Combined, these data strongly implicate the 4 bp 5' deletion as a causal mutation in Duarte galactosemia and suggest that direct tests for this deletion, as proposed here, could enhance or supplant current tests, which define D2 alleles on the basis of the presence and absence of linked coding sequence polymorphisms.