Self-identified prescriber tendencies in sodium-glucose cotransporter-2 inhibitor outpatient prescribing.

BACKGROUND: Despite expanded indications and demonstrated cardiovascular and renal benefits, prescribing rates of sodium-glucose cotransporter-2 (SGLT-2) inhibitors are low. OBJECTIVES: The study aimed to identify factors impacting prescriber decision-making when prescribing SGLT-2 inhibitors in the outpatient setting and identify differences across specialties in self-identified prescribing patterns. METHODS: An anonymous survey was administered electronically to prescribers in relevant specialties at a large community health system. Descriptive statistics were used to compile results, and subgroup comparisons were conducted utilizing Fisher's exact test. RESULTS: Fifty-one prescribers completed the survey, representing a 25.2% response rate. The highest reported prescribing rates were for type 2 diabetes (92%), and the lowest for HFpEF (20%) and ASCVD risk reduction (16%). Prescribers without clinic-embedded pharmacist were more likely to report cost and insurance had at least a moderate effect on prescribing compared to prescribers with clinic-embedded pharmacists (95.3% vs. 62.5%, P = 0.0228) and less likely to report hemoglobin A1c less than 6.5% to have at least a moderate effect on prescribing (20.9% vs. 62.5%, P = 0.0317). Compared to specialty providers, primary care prescribers were more likely to report hemoglobin A1c over 9% had at least a moderate effect on prescribing (92.0% vs. 42.9%, P = 0.0082) and less likely to note history of urinary tract infection (22.2% vs. 85.7%, P = 0.0028), history of mycotic infection (38.9% vs. 100%, P = 0.0036), and sex (male: 5.6% vs. 42.9%, P = 0.0242; female: 8.0% vs. 42.9%, P = 0.0447) had at least a moderate effect on prescribing. CONCLUSION: Prescribing hesitancies vary across specialty and when clinic-embedded pharmacists are present. Pharmacists may help improve SGLT-2 inhibitor prescribing rates and use of guideline-directed therapies. Pharmacists can target identified hesitancies through medication-access consultations, education regarding adverse effects, and expanded benefits of the class. Future studies should examine the impact of pharmacist intervention on SGLT-2 inhibitor prescribing rates.

Coordinated interplay between palmitoylation, phosphorylation and SUMOylation regulates kainate receptor surface expression.

Kainate receptors (KARs) are key regulators of neuronal excitability and synaptic transmission. KAR surface expression is tightly controlled in part by post-translational modifications (PTMs) of the GluK2 subunit. We have shown previously that agonist activation of GluK2-containing KARs leads to phosphorylation of GluK2 at S868, which promotes subsequent SUMOylation at K886 and receptor endocytosis. Furthermore, GluK2 has been shown to be palmitoylated. However, how the interplay between palmitoylation, phosphorylation and SUMOylation orchestrate KAR trafficking remains unclear. Here, we used a library of site-specific GluK2 mutants to investigate the interrelationship between GluK2 PTMs, and their impact on KAR surface expression. We show that GluK2 is basally palmitoylated and that this is decreased by kainate (KA) stimulation. Moreover, a non-palmitoylatable GluK2 mutant (C858/C871A) shows enhanced S868 phosphorylation and K886 SUMOylation under basal conditions and is insensitive to KA-induced internalisation. These results indicate that GluK2 palmitoylation contributes to stabilising KAR surface expression and that dynamic depalmitoylation promotes downstream phosphorylation and SUMOylation to mediate activity-dependent KAR endocytosis.

SNX27-Retromer directly binds ESCPE-1 to transfer cargo proteins during endosomal recycling.

Coat complexes coordinate cargo recognition through cargo adaptors with biogenesis of transport carriers during integral membrane protein trafficking. Here, we combine biochemical, structural, and cellular analyses to establish the mechanistic basis through which SNX27-Retromer, a major endosomal cargo adaptor, couples to the membrane remodeling endosomal SNX-BAR sorting complex for promoting exit 1 (ESCPE-1). In showing that the SNX27 FERM (4.1/ezrin/radixin/moesin) domain directly binds acidic-Asp-Leu-Phe (aDLF) motifs in the SNX1/SNX2 subunits of ESCPE-1, we propose a handover model where SNX27-Retromer captured cargo proteins are transferred into ESCPE-1 transport carriers to promote endosome-to-plasma membrane recycling. By revealing that assembly of the SNX27:Retromer:ESCPE-1 coat evolved in a stepwise manner during early metazoan evolution, likely reflecting the increasing complexity of endosome-to-plasma membrane recycling from the ancestral opisthokont to modern animals, we provide further evidence of the functional diversification of yeast pentameric Retromer in the recycling of hundreds of integral membrane proteins in metazoans.

Sorting nexin-27 regulates AMPA receptor trafficking through the synaptic adhesion protein LRFN2.

The endosome-associated cargo adaptor sorting nexin-27 (SNX27) is linked to various neuropathologies through sorting of integral proteins to the synaptic surface, most notably AMPA receptors. To provide a broader view of SNX27-associated pathologies, we performed proteomics in rat primary neurons to identify SNX27-dependent cargoes, and identified proteins linked to excitotoxicity, epilepsy, intellectual disabilities, and working memory deficits. Focusing on the synaptic adhesion molecule LRFN2, we established that SNX27 binds to LRFN2 and regulates its endosomal sorting. Furthermore, LRFN2 associates with AMPA receptors and knockdown of LRFN2 results in decreased surface AMPA receptor expression, reduced synaptic activity, and attenuated hippocampal long-term potentiation. Overall, our study provides an additional mechanism by which SNX27 can control AMPA receptor-mediated synaptic transmission and plasticity indirectly through the sorting of LRFN2 and offers molecular insight into the perturbed function of SNX27 and LRFN2 in a range of neurological conditions.

Perchloroethylene and Dry Cleaning: It's Time to Move the Industry to Safer Alternatives.

Perchloroethylene (PERC) is the most common solvent used for dry cleaning in the United States. PERC is a reproductive toxicant, neurotoxicant, potential human carcinogen, and a persistent environmental pollutant. The Environmental Protection Agency is evaluating PERC under the Frank R. Lautenberg Chemical Safety for the 21st Century Act, which amended the Toxic Substances Control Act (amended TSCA), and has mandated that PERC dry cleaning machines be removed from residential buildings. Some local and state programs are also requiring or facilitating transitions to alternative cleaning technologies. However, the potential for these alternatives to harm human health and the environment is not well-understood. This review describes the issues surrounding the use of PERC and alternative solvents for dry cleaning while highlighting the lessons learned from a local government program that transitioned PERC dry cleaners to the safest current alternative: professional wet cleaning. Implications for future public health research and policy are discussed: (1) we must move away from PERC, (2) any transition must account for the economic instability and cultural aspects of the people who work in the industry, (3) legacy contamination must be addressed even after safer alternatives are adopted, and (4) evaluations of PERC alternatives are needed to determine their implications for the long-term health and sustainability of the people who work in the industry.

Feasibility of virtual reality behavior skills training for preservice clinicians.

Effective training procedures include behavioral skills training (BST), which involves providing written and verbal instructions, modeling of the skill, rehearsal of the skill, and feedback on the performance. This training typically involves in vivo experience in which trainees and students are exposed to risks such as proximity to infectious disease, behavioral issues such as aggression, and errors in teaching performance. Conducting BST in a virtual reality (VR) context involving virtual individuals with problem behavior may be an effective means of mitigating these risks. The purpose of this study was to examine the feasibility of training students to conduct functional communication training (FCT) in a VR environment using BST. We trained 13 preservice college students to implement FCT for attention and escape functions. We found VR BST was effective at increasing correct steps performed of FCT to mastery criterion levels with all participants. Future researchers should examine generalization and maintenance of VR BST.

Corrigendum: Protein Interactors and Trafficking Pathways That Regulate the Cannabinoid Type 1 Receptor (CB1R).

[This corrects the article DOI: 10.3389/fnmol.2020.00108.].

Acute inactivation of retromer and ESCPE-1 leads to time-resolved defects in endosomal cargo sorting.

Human retromer, a heterotrimer of VPS26 (VPS26A or VPS26B), VPS35 and VPS29, orchestrates the endosomal retrieval of internalised cargo and promotes their cell surface recycling, a prototypical cargo being the glucose transporter GLUT1 (also known as SLC2A1). The role of retromer in the retrograde sorting of the cation-independent mannose 6-phosphate receptor (CI-MPR, also known as IGF2R) from endosomes back to the trans-Golgi network remains controversial. Here, by applying knocksideways technology, we develop a method for acute retromer inactivation. While retromer knocksideways in HeLa and H4 human neuroglioma cells resulted in time-resolved defects in cell surface sorting of GLUT1, we failed to observe a quantifiable defect in CI-MPR sorting. In contrast, knocksideways of the ESCPE-1 complex - a key regulator of retrograde CI-MPR sorting - revealed time-resolved defects in CI-MPR sorting. Together, these data are consistent with a comparatively limited role for retromer in ESCPE-1-mediated CI-MPR retrograde sorting, and establish a methodology for acute retromer and ESCPE-1 inactivation that will aid the time-resolved dissection of their functional roles in endosomal cargo sorting.

Protein Interactors and Trafficking Pathways That Regulate the Cannabinoid Type 1 Receptor (CB1R).

The endocannabinoid system (ECS) acts as a negative feedback mechanism to suppress synaptic transmission and plays a major role in a diverse range of brain functions including, for example, the regulation of mood, energy balance, and learning and memory. The function and dysfunction of the ECS are strongly implicated in multiple psychiatric, neurological, and neurodegenerative diseases. Cannabinoid type 1 receptor (CB1R) is the most abundant G protein-coupled receptor (GPCR) expressed in the brain and, as for any synaptic receptor, CB1R needs to be in the right place at the right time to respond appropriately to changing synaptic circumstances. While CB1R is found intracellularly throughout neurons, its surface expression is highly polarized to the axonal membrane, consistent with its functional expression at presynaptic sites. Surprisingly, despite the importance of CB1R, the interacting proteins and molecular mechanisms that regulate the highly polarized distribution and function of CB1R remain relatively poorly understood. Here we set out what is currently known about the trafficking pathways and protein interactions that underpin the surface expression and axonal polarity of CB1R, and highlight key questions that still need to be addressed.

Pre-treatment T-cell subsets associate with fingolimod treatment responsiveness in multiple sclerosis.

Biomarkers predicting fingolimod (FTY) treatment response in relapsing-remitting multiple sclerosis (RRMS) are lacking. Here, we performed extensive functional immunophenotyping using multiparametric flow cytometry to examine peripheral immune changes under FTY treatment and explore biomarkers of FTY treatment response. From among 135 RRMS patients who initiated FTY in a 2-year multicentre observational study, 36 were classified as 'Active' or 'Stable' based on clinical and/or radiological activity on-treatment. Flow cytometric analysis of immune cell subsets was performed on pre- and on-treatment peripheral blood mononuclear cells (PBMC) samples. Decreased absolute counts of B cells and most T-cell subsets were seen on-treatment. Senescent CD8 + T cells, CD56 + T cells, CD56dim natural killer cells, monocytes and dendritic cells were not reduced in number and hence relatively increased in frequency on-treatment. An unbiased multiparametric and traditional manual analysis of T-cell subsets suggested a higher pre-treatment frequency of CD4 + central memory T cells (TCM) in patients who were subsequently Active versus Stable on-treatment. Lower pre-treatment terminally differentiated effector memory (TEMRA) cell frequencies were also seen in the subsequently Active cohort. Together, our data highlight differential effects of FTY on peripheral immune cell subsets and suggest that pre-treatment T-cell subset frequencies may have value in predicting FTY treatment response.

Effects of geographic location and water quality on bacterial communities in full-scale biofilters across North America.

Spatial patterns of bacterial community composition often follow a distance-decay relationship in which community dissimilarity increases with geographic distance. Such a relationship has been commonly observed in natural environments, but less so in engineered environments. In this study, bacterial abundance and community composition in filter media samples (n = 57) from full-scale rapid biofilters at 14 water treatment facilities across North America were determined using quantitative polymerase chain reaction and Illumina HiSeq high-throughput sequencing targeting the 16S rRNA gene, respectively. Bacteria were abundant on the filter media (108.8±0.3 to 1010.7±0.2 16S rRNA gene copies/cm3 bed volume) and the bacterial communities were highly diverse (Shannon index: 5.3 ± 0.1 to 8.4 ± 0.0). Significant inter-filter variations in bacterial community composition were observed, with weighted UniFrac dissimilarity values following a weak but highly significant distance-decay relationship (z = 0.0057 ± 0.0006; P = 1.8 × 10-22). Approximately 50% of the variance in bacterial community composition was explained by the water quality parameters measured at the time of media sample collection (i.e. pH, temperature and dissolved organic carbon concentration). Overall, this study suggested that the microbiomes of biofilters are primarily shaped by geographic location and local water quality conditions but the influence of these factors on the microbiomes is tempered by filter design and operating conditions.

Bench-scale column evaluation of factors associated with changes in N-nitrosodimethylamine (NDMA) precursor concentrations during drinking water biofiltration.

Biofiltration has been observed to increase or decrease the concentrations of N-nitrosodimethylamine (NDMA) precursors in the effluents of full-scale drinking water facilities, but these changes have been inconsistent over time. Bench-scale tests comparing biofiltration columns side-by-side exposed to different conditions were employed to characterize factors associated with changes in NDMA precursor concentrations, as measured by application of chloramines under uniform formation conditions (UFC). Side-by-side comparisons of biofiltration media from different facilities fed with water from each of these facilities demonstrated that differences in source water quality were far more important than any original differences in the microbial communities on the biofiltration media for determining whether NDMA precursor concentrations increased, decreased or remained constant across biofilters. Additional tests involving spiking of specific constituents hypothesized to promote increases in NDMA precursor concentrations demonstrated that inorganic nitrogen species associated with nitrification, including ammonia, hydroxylamine and chloramines, and biotransformation of known precursors (i.e., municipal wastewater and the cationic polymer, polyDADMAC) to more potent forms were not important. Biotransformation of uncharacterized components of source waters determined whether NDMA precursor concentrations increased or decreased across biofilters. These uncharacterized source water component concentrations varied temporally and across locations. Where biotransformation of source water precursors increased NDMA precursor concentrations, ∼30-60% of the levels observed in column effluents fed with biofiltration influent water remained associated with the media and could be rinsed therefrom in either the dissolved or particulate form. Ozone pre-treatment significantly reduced NDMA precursor concentrations at one facility, suggesting that pre-oxidation could be an effective technique to mitigate the increase in NDMA precursor concentrations during biofiltration. Biofiltration decreased the concentrations of halogenated disinfection byproduct precursors.

The C-terminal helix 9 motif in rat cannabinoid receptor type 1 regulates axonal trafficking and surface expression.

Cannabinoid type one receptor (CB1R) is only stably surface expressed in axons, where it downregulates neurotransmitter release. How this tightly regulated axonal surface polarity is established and maintained is unclear. To address this question, we used time-resolved imaging to determine the trafficking of CB1R from biosynthesis to mature polarised localisation in cultured rat hippocampal neurons. We show that the secretory pathway delivery of CB1R is axonally biased and that surface expressed CB1R is more stable in axons than in dendrites. This dual mechanism is mediated by the CB1R C-terminus and involves the Helix 9 (H9) domain. Removal of the H9 domain increases secretory pathway delivery to dendrites and decreases surface stability. Furthermore, CB1RΔH9 is more sensitive to agonist-induced internalisation and less efficient at downstream signalling than CB1RWT. Together, these results shed new light on how polarity of CB1R is mediated and indicate that the C-terminal H9 domain plays key roles in this process.

Exciting Times: New Advances Towards Understanding the Regulation and Roles of Kainate Receptors.

Kainate receptors (KARs) are glutamate-gated ion channels that play fundamental roles in regulating neuronal excitability and network function in the brain. After being cloned in the 1990s, important progress has been made in understanding the mechanisms controlling the molecular and cellular properties of KARs, and the nature and extent of their regulation of wider neuronal activity. However, there have been significant recent advances towards understanding KAR trafficking through the secretory pathway, their precise synaptic positioning, and their roles in synaptic plasticity and disease. Here we provide an overview highlighting these new findings about the mechanisms controlling KARs and how KARs, in turn, regulate other proteins and pathways to influence synaptic function.

ADAR2-mediated Q/R editing of GluK2 regulates kainate receptor upscaling in response to suppression of synaptic activity.

Kainate receptors (KARs) regulate neuronal excitability and network function. Most KARs contain the subunit GluK2 (also known as GRIK2), and the properties of these receptors are determined in part by ADAR2 (also known as ADARB1)-mediated mRNA editing of GluK2, which changes a genomically encoded glutamine residue into an arginine residue (Q/R editing). Suppression of synaptic activity reduces ADAR2-dependent Q/R editing of GluK2 with a consequential increase in GluK2-containing KAR surface expression. However, the mechanism underlying this reduction in GluK2 editing has not been addressed. Here, we show that induction of KAR upscaling, a phenomenon in which surface expression of receptors is increased in response to a chronic decrease in synaptic activity, results in proteasomal degradation of ADAR2, which reduces GluK2 Q/R editing. Because KARs incorporating unedited GluK2(Q) assemble and exit the ER more efficiently, this leads to an upscaling of KAR surface expression. Consistent with this, we demonstrate that partial ADAR2 knockdown phenocopies and occludes KAR upscaling. Moreover, we show that although the AMPA receptor (AMPAR) subunit GluA2 (also known as GRIA2) also undergoes ADAR2-dependent Q/R editing, this process does not mediate AMPAR upscaling. These data demonstrate that activity-dependent regulation of ADAR2 proteostasis and GluK2 Q/R editing are key determinants of KAR, but not AMPAR, trafficking and upscaling.This article has an associated First Person interview with the first author of the paper.

Assembly, Secretory Pathway Trafficking, and Surface Delivery of Kainate Receptors Is Regulated by Neuronal Activity.

Ionotropic glutamate receptor (iGluR) trafficking and function underpin excitatory synaptic transmission and plasticity and shape neuronal networks. It is well established that the transcription, translation, and endocytosis/recycling of iGluRs are all regulated by neuronal activity, but much less is known about the activity dependence of iGluR transport through the secretory pathway. Here, we use the kainate receptor subunit GluK2 as a model iGluR cargo to show that the assembly, early secretory pathway trafficking, and surface delivery of iGluRs are all controlled by neuronal activity. We show that the delivery of de novo kainate receptors is differentially regulated by modulation of GluK2 Q/R editing, PKC phosphorylation, and PDZ ligand interactions. These findings reveal that, in addition to short-term regulation of iGluRs by recycling/endocytosis and long-term modulation by altered transcription/translation, the trafficking of iGluRs through the secretory pathway is under tight activity-dependent control to determine the numbers and properties of surface-expressed iGluRs.

Dimethyl fumarate-induced lymphopenia in MS due to differential T-cell subset apoptosis.

OBJECTIVE: To examine the mechanism underlying the preferential CD8+ vs CD4+ T-cell lymphopenia induced by dimethyl fumarate (DMF) treatment of MS. METHODS: Total lymphocyte counts and comprehensive T-cell subset analyses were performed in high-quality samples obtained from patients with MS prior to and serially following DMF treatment initiation. Random coefficient mixed-effects analysis was used to model the trajectory of T-cell subset losses in vivo. Survival and apoptosis of distinct T-cell subsets were assessed following in vitro exposure to DMF. RESULTS: Best-fit modeling indicated that the DMF-induced preferential reductions in CD8+ vs CD4+ T-cell counts nonetheless followed similar depletion kinetics, suggesting a similar rather than distinct mechanism involved in losses of both the CD8+ and CD4+ T cells. In vitro, DMF exposure resulted in dose-dependent reductions in T-cell survival, which were found to reflect apoptotic cell death. This DMF-induced apoptosis was greater for CD8+ vs CD4+, as well as for memory vs naive, and conventional vs regulatory T-cell subsets, a pattern which mirrored preferential T-cell subset losses that we observed during in vivo treatment of patients. CONCLUSIONS: Differential apoptosis mediated by DMF may underlie the preferential lymphopenia of distinct T-cell subsets, including CD8+ and memory T-cell subsets, seen in treated patients with MS. This differential susceptibility of distinct T-cell subsets to DMF-induced apoptosis may contribute to both the safety and efficacy profiles of DMF in patients with MS.

SENP3-mediated deSUMOylation of Drp1 facilitates interaction with Mff to promote cell death.

The GTPase dynamin-related protein 1 (Drp1) is essential for physiological and pathophysiological mitochondrial fission. DeSUMOylation of Drp1 by the enzyme SENP3 promotes cell death during reperfusion after ischaemia by enhancing Drp1 partitioning to the mitochondrial outer membrane (MOM), which causes cytochrome c release and apoptosis. However, how deSUMOylation recruits Drp1 to the MOM is unknown. Here we show that deSUMOylation selectively promotes Drp1 binding to the MOM resident adaptor protein mitochondrial fission factor (Mff). Consistent with this, preventing Drp1 SUMOylation by mutating the SUMO acceptor sites enhances binding to Mff. Conversely, increasing Drp1 SUMOylation by knocking down SENP3 reduces both Drp1 binding to Mff and stress-induced cytochrome c release. Directly tethering Drp1 to the MOM bypasses the need for Mff to evoke cytochrome c release, and occludes the effect of SENP3 overexpression. Thus, Drp1 deSUMOylation promotes cell death by enhancing Mff-mediated mitochondrial recruitment. These data provide a mechanistic explanation for how the SUMOylation status of Drp1 acts as a key switch in cell death/survival decisions following extreme cell stress.

Expanding the Reach of Effective PTSD Treatment Into Primary Care: Prolonged Exposure for Primary Care.

Posttraumatic stress disorder (PTSD) is a costly mental health issue in the United States and throughout the world. Effective treatments are available; however, most people with PTSD never access these treatments. Prolonged exposure (PE) therapy has emerged as an effective, first-line treatment for PTSD and is provided in specialty mental health in eight to 15 sessions, each lasting 90 minutes. Most people with PTSD do not enter specialty mental health to access this service. Over the past 15 years, provision of mental health care in primary care has increased due to patient preference for care in this setting and the ability to overcome many access barriers (stigma, longer sessions, insurance coverage, etc.). While medications for PTSD are available in primary care, effective brief psychotherapeutic PTSD treatment options have only recently been established. PE-PC (prolonged exposure for primary care) is a brief version of PE therapy for PTSD with efficacy in a primary care (PC) setting in reducing PTSD, depression, and related mental disorder symptoms. PE-PC has four 30-minute sessions and focuses on imaginal exposure to the trauma memory, in vivo exposure to trauma-related avoidance, and emotional processing of the memory. Dissemination efforts are currently underway to expand availability.

Mortality outcomes after busulfan-containing conditioning treatment and haemopoietic cell transplantation in patients with Gilbert's syndrome: a retrospective cohort study.

BACKGROUND: Gilbert's syndrome is a common inherited disorder of bilirubin metabolism, characterised by mild, unconjugated hyperbilirubinaemia. However, the effect of Gilbert's syndrome on the disposition of some drugs can lead to unexpected toxicity. We tested the hypothesis that patients undergoing myeloablative conditioning and haemopoietic cell transplantation would have different mortality outcomes depending on whether or not they had laboratory evidence of Gilbert's syndrome. METHODS: In this retrospective cohort study, we used clinical and laboratory data of patients who had haemopoietic cell transplantation from Jan 1, 1991, to Dec 31, 2011. Patients were included if they had received high-dose conditioning regimens of cyclophosphamide plus total body irradiation (CY/TBI), busulfan plus cyclophosphamide (BU/CY), busulfan plus melphalan plus thioTEPA (BUMELTT), or melphalan before transplant. Patients were excluded if their original consent forms to report transplant outcomes were not signed, if consent was withdrawn, or if they were a prisoner. Patients with Gilbert's syndrome were defined as having laboratory values before the start of conditioning therapy for unconjugated serum bilirubin concentrations of at least 17·1 µmol/L (≥1 mg/dL), normal conjugated serum bilirubin, and no evidence of hepatitis, cholestasis, or haemolysis. We assessed the association of Gilbert's syndrome with overall mortality and non-relapse mortality using adjusted Cox regression models at day 200 after transplantation. FINDINGS: Our study cohort was 3379 patients-1855 (55%) allograft and 1524 (45%) autograft recipients. 211 (6%) patients had Gilbert's syndrome and 3168 (94%) did not have this condition. Most patients were adults (median age 45·8 years [IQR 33·2-55·5]) with haematological malignancies. For overall mortality 664 (20%) patients had died by day 200 after transplant (47 [22%] of 211 who had Gilbert's syndrome vs 617 [19%] of 3168 who did not have Gilbert's syndrome), and for non-relapse mortality 499 (92%) patients had died before relapse was recorded (38 [18%] who had Gilbert's syndrome vs 461 [15%] who did not have Gilbert's syndrome). The effect of Gilbert's syndrome on the risk of overall mortality and non-relapse mortality by transplant day 200 varied between the conditioning regimens and donor groups. In patients conditioned with a myeloablative regimen that contained busulfan (n=1131), those with Gilbert's syndrome (n=60) were at a significantly increased risk of death and non-relapse mortality by day 200 compared with those without Gilbert's syndrome (n=1071; hazard ratio [HR] 2·30, 95% CI 1·47-3·61, p=0·00030; and 2·77, 1·71-4·49, p<0·0001). In patients who received CY/TBI or melphalan conditioning regimens, those with Gilbert's syndrome had similar outcomes to those without Gilbert's syndrome (overall mortality at day 200 HR 0·90, 95% CI 0·60-1·34, p=0·60; non-relapse mortality at day 200: 0·90, 0·56-1·45, p=0·65). Analyses of causes of death and busulfan disposition provided no mechanistic explanation for the differences in mortality. INTERPRETATION: Overall mortality and non-relapse mortality at day 200 after transplant were significantly worse in patients with Gilbert's syndrome who received busulfan-containing myeloablative conditioning regimens, compared with non-Gilbert's syndrome patients. Patients with Gilbert's syndrome should receive busulfan-containing myeloablative conditioning regimens with caution. FUNDING: US National Institutes of Health.