The Promise and Risks of mHealth in Heart Failure Care.

Mobile health (mHealth) is an emerging approach to health care. It involves wearable, connected technologies that facilitate patient-symptom or physiological monitoring, support clinical feedback to patients and physicians, and promote patients' education and self-care. Evolving algorithms may involve artificial intelligence and can assist in data aggregation and health care teams' interpretations. Ultimately, the goal is not merely to collect data; rather, it is to increase actionability. mHealth technology holds particular promise for patients with heart failure, especially those with frequently changing clinical status. mHealth, ideally, can identify care opportunities, anticipate clinical courses and augment providers' capacity to implement, titrate and monitor interventions safely, including evidence-based therapies. Although there have been marked advancements in the past decade, uncertainties remain for mHealth, including questions regarding optimal indications and acceptable payment models. In regard to mHealth capability, a better understanding is needed of the incremental benefit of mHealth data over usual care, the accuracy of specific mHealth data points in making clinical care decisions, and the efficiency and precision of algorithms used to dictate actions. Importantly, emerging regulations in the wake of COVID-19, and now the end of the federal public health emergency, offer both opportunity and risks to the broader adoption of mHealth-enabled services. In this review, we explore the current state of mHealth in heart failure, with particular attention to the opportunities and challenges this technology creates for patients, health care providers and other stakeholders.

Estimating the burden of influenza-attributable severe acute respiratory infections on the hospital system in Metropolitan France, 2012-2018.

BACKGROUND: To date, estimating the burden of seasonal influenza on the hospital system in France has been restricted to influenza diagnoses in patients (estimated hospitalization rate of 35/100,000 on average from 2012 to 2018). However, many hospitalizations for diagnosed respiratory infections (e.g. pneumonia, acute bronchitis) occur without concurrent screening for virological influenza, especially in the elderly. Specifically, we aimed to estimate the burden of influenza on the French hospital system by examining the proportion of severe acute respiratory infections (SARI) attributable to influenza. METHODS: Using French national hospital discharge data from 1/7/2012 to 30/6/2018, we extracted SARI hospitalizations with ICD-10 codes J09-J11 (influenza codes) in main or associated diagnoses, and J12-J20 (pneumonia and bronchitis codes) in main diagnoses. We estimated influenza-attributable SARI hospitalizations during influenza epidemics, as the number of influenza-coded hospitalizations plus the influenza-attributable number of pneumonia- and acute bronchitis-coded hospitalizations using periodic regression and generalized linear models. Additional analyses stratified by age group, diagnostic category (pneumonia and bronchitis), and region of hospitalization were performed using the periodic regression model only. RESULTS: The average estimated hospitalization rate of influenza-attributable SARI during the five annual influenza epidemics covered (2013-2014 to 2017-2018) was 60/100,000 with the periodic regression model, and 64/100,000 with the generalized linear model. Over the six epidemics (2012-2013 to 2017-2018), of the 533,456 SARI hospitalizations identified, an estimated 227,154 were influenza-attributable (43%). Fifty-six percent of cases were diagnosed with influenza, 33% pneumonia, and 11% bronchitis. Diagnoses varied between age groups: 11% of patients under 15 years old had pneumonia versus 41% of patients aged 65 and older. CONCLUSION: Compared to influenza surveillance in France to date, analyzing excess SARI hospitalizations provided a much larger estimate of the burden of influenza on the hospital system. This approach was more representative and allowed the burden to be assessed according to age group and region. The emergence of SARS-Cov-2 has led to a change in the dynamics of winter respiratory epidemics. The co-circulation of the three current major respiratory viruses (influenza, SARS-Cov-2, and RSV) and the evolution of diagnostic confirmation practices must now be taken into account when analyzing SARI.

Predicting genotoxicity of viral vectors for stem cell gene therapy using gene expression-based machine learning.

Hematopoietic stem cell gene therapy is emerging as a promising therapeutic strategy for many diseases of the blood and immune system. However, several individuals who underwent gene therapy in different trials developed hematological malignancies caused by insertional mutagenesis. Preclinical assessment of vector safety remains challenging because there are few reliable assays to screen for potential insertional mutagenesis effects in vitro. Here we demonstrate that genotoxic vectors induce a unique gene expression signature linked to stemness and oncogenesis in transduced murine hematopoietic stem and progenitor cells. Based on this finding, we developed the surrogate assay for genotoxicity assessment (SAGA). SAGA classifies integrating retroviral vectors using machine learning to detect this gene expression signature during the course of in vitro immortalization. On a set of benchmark vectors with known genotoxic potential, SAGA achieved an accuracy of 90.9%. SAGA is more robust and sensitive and faster than previous assays and reliably predicts a mutagenic risk for vectors that led to leukemic severe adverse events in clinical trials. Our work provides a fast and robust tool for preclinical risk assessment of gene therapy vectors, potentially paving the way for safer gene therapy trials.

Isotope ratio infrared spectroscopy analysis of water samples without memory effects.

RATIONALE: Since their introduction more than a decade ago, isotope ratio infrared spectroscopy (IRIS) systems have rapidly become the standard for oxygen (δ18 O) and hydrogen (δ2 H) isotope analysis of water samples. An important disadvantage of IRIS systems is the well-documented sample-to-sample memory effect, which requires each sample to be analyzed multiple times before the desired accuracy is reached, lengthening analysis times and driving up the costs of analyses. METHODS: We present an adapted set-up and calculation protocol for fully automated analysis of water samples using a Picarro L2140-i cavity ring-down spectroscopy instrument. The adaptation removes memory effects by use of a continuously moisturized nitrogen carrier gas. Water samples of 0.5 µL are measured on top of the water vapor background, after which isotope ratios are calculated by subtraction of the background from the sample peaks. RESULTS: With this new technique, single injections of water samples have internal precisions (1σ) below 0.05‰ for δ18 O values and 0.1‰ for δ2 H values, regardless of the isotope ratio of the previous sample. Precision is worse, however, when the isotope difference between the sample and background water is too large (i.e., exceeding approximately 9‰ for δ18 O values and 70‰ for δ2 H values). Isotope ratios show negligible drift across the four weeks within which the experiments were performed. The single-injection 1σ precision for 17 O excess (Δ'17 O) determined with this method is 60 per meg. CONCLUSIONS: Our experiments demonstrate that by removing sample-to-sample memory effects with a moisturized carrier gas, the time for measurement of δ18 O and δ2 H values using an IRIS system can be reduced markedly without compromising the analytical precision and accuracy. Thorough replication is needed to achieve sufficiently low uncertainties for Δ'17 O.

Lentiviral gene therapy rescues p47phox chronic granulomatous disease and the ability to fight Salmonella infection in mice.

Chronic granulomatous disease (CGD) is an inherited primary immunodeficiency disorder characterised by recurrent and often life-threatening infections and hyperinflammation. It is caused by defects of the phagocytic NADPH oxidase, a multicomponent enzyme system responsible for effective pathogen killing. A phase I/II clinical trial of lentiviral gene therapy is underway for the most common form of CGD, X-linked, caused by mutations in the gp91phox subunit of the NADPH oxidase. We propose to use a similar strategy to tackle p47phox-deficient CGD, caused by mutations in NCF1, which encodes the p47phox cytosolic component of the enzymatic complex. We generated a pCCLCHIM-p47phox lentiviral vector, containing the chimeric Cathepsin G/FES myeloid promoter and a codon-optimised version of the human NCF1 cDNA. Here we show that transduction with the pCCLCHIM-p47phox vector efficiently restores p47phox expression and biochemical NADPH oxidase function in p47phox-deficient human and murine cells. We also tested the ability of our gene therapy approach to control infection by challenging p47phox-null mice with Salmonella Typhimurium, a leading cause of sepsis in CGD patients, and found that mice reconstituted with lentivirus-transduced hematopoietic stem cells had a reduced bacterial load compared with untreated mice. Overall, our results potentially support the clinical development of a gene therapy approach using the pCCLCHIM-p47phox vector.

Megacity development and the demise of coastal coral communities: Evidence from coral skeleton δ15 N records in the Pearl River estuary.

Historical coral skeleton (CS) δ18 O and δ15 N records were produced from samples recovered from sedimentary deposits, held in natural history museum collections, and cored into modern coral heads. These records were used to assess the influence of global warming and regional eutrophication, respectively, on the decline of coastal coral communities following the development of the Pearl River Delta (PRD) megacity, China. We find that, until 2007, ocean warming was not a major threat to coral communities in the Pearl River estuary; instead, nitrogen (N) inputs dominated impacts. The high but stable CS-δ15 N values (9‰-12‰ vs. air) observed from the mid-Holocene until 1980 indicate that soil and stream denitrification reduced and modulated the hydrologic inputs of N, blunting the rise in coastal N sources during the early phase of the Pearl River estuary urbanization. However, an unprecedented CS-δ15 N peak was observed from 1987 to 1993 (>13‰ vs. air), concomitant to an increase of NH4+ concentration, consistent with the rapid Pearl River estuary urbanization as the main cause for this eutrophication event. We suggest that widespread discharge of domestic sewage entered directly into the estuary, preventing removal by natural denitrification hotspots. We argue that this event caused the dramatic decline of the Pearl River estuary coral communities reported from 1980 to 2000. Subsequently, the coral record shows that the implementation of improved wastewater management policies succeeded in bringing down both CS-δ15 N and NH4+ concentrations in the early 2000s. This study points to the potential importance of eutrophication over ocean warming in coral decline along urbanized coastlines and in particular in the vicinity of megacities.

A comparison of isotope ratio mass spectrometry and cavity ring-down spectroscopy techniques for isotope analysis of fluid inclusion water.

RATIONALE: Online oxygen (δ18 O) and hydrogen (δ2 H) isotope analysis of fluid inclusion water entrapped in minerals is widely applied in paleo-fluid studies. In the state of the art of fluid inclusion isotope research, however, there is a scarcity of reported inter-technique comparisons to account for possible analytical offsets. Along with improving analytical precisions and sample size limitations, interlaboratory comparisons can lead to a more robust application of fluid inclusion isotope records. METHODS: Mineral samples-including speleothem, travertine, and vein material-were analyzed on two newly setup systems for fluid inclusion isotope analysis to provide an inter-platform comparison. One setup uses a crusher unit connected online to a continuous-flow pyrolysis furnace and an isotope ratio mass spectrometry (IRMS) instrument. In the other setup, a crusher unit is lined up with a cavity ring-down spectroscopy (CRDS) system, and water samples are analyzed on a continuous standard water background to achieve precisions on water injections better than 0.1‰ for δ18 O values and 0.4‰ for δ2 H values for amounts down to 0.2 µL. RESULTS: Fluid inclusion isotope analyses on the IRMS setup have an average 1σ reproducibility of 0.4‰ and 2.0‰ for δ18 O and δ2 H values, respectively. The CRDS setup has a better 1σ reproducibility (0.3‰ for δ18 O values and 1.1‰ for δ2 H values) and also a more rapid sample throughput (<30 min per sample). Fluid inclusion isotope analyses are reproducible at these uncertainties for water amounts down to 0.1 µL on both setups. Fluid inclusion isotope data show no systematic offsets between the setups. CONCLUSIONS: The close match in fluid inclusion isotope results between the two setups demonstrates the high accuracy of the presented continuous-flow techniques for fluid inclusion isotope analysis. Ideally, experiments such as the one presented in this study will lead to further interlaboratory comparison efforts and the selection of suitable reference materials for fluid inclusion isotopes studies.

High-precision stable isotope analysis of <5 µg CaCO3 samples by continuous-flow mass spectrometry.

RATIONALE: Oxygen (δ18 O) and carbon (δ13 C) isotope analysis of foraminifera and other CaCO3 samples has been a key technique for paleoceanographical and paleoclimatological research for more than 60 years. There is ongoing demand for the analysis of ever smaller CaCO3 samples, driven, for example, by the desire to analyse single specimen planktic foraminifera, or small samples of tooth enamel. METHODS: We present a continuous-flow mass spectrometric technique that uses cryo-focusing of sample CO2 to analyse CaCO3 samples in a weight range between 10 and 3 µg. These are considerably lower sample weights than achievable on most currently available standard instrumentation. The technique is automated, so that sample throughput lies at >60 samples per day. The method involves an on-line vial-flushing routine designed to remove machine drift due to blank CO2 build-up in the sample vials. RESULTS: In a series of experiments the effect of blank CO2 build-up is quantified, and outgassing from the chlorobutyl septa identified as the source. An improved flushing routine together with the use of a cryo-focusing step in the analysis is demonstrated to provide the analytical stability and sensitivity to analyse CaCO3 samples in a weight range between 10 and 3 µg at ≤0.1‰ precision (1σ) for both δ18 O and δ13 C values. The technique yields similarly precise results for the analysis of the structural carbonate fraction of small tooth enamel samples. CONCLUSIONS: This study demonstrates that high-precision oxygen and carbon isotope analysis is possible on CaCO3 samples smaller than 5 µg by use of a continuous-flow isotope technique. Of key importance are (1) the application of a cold trap that drastically reduces sample gas loss, and (2) a modified flushing regime that eliminates increasing background CO2 build-up in sample vials during longer automated sample runs.

Reticular dysgenesis: international survey on clinical presentation, transplantation, and outcome.

Reticular dysgenesis (RD) is a rare congenital disorder defined clinically by the combination of severe combined immunodeficiency (SCID), agranulocytosis, and sensorineural deafness. Mutations in the gene encoding adenylate kinase 2 were identified to cause the disorder. Hematopoietic stem cell transplantation (HSCT) is the only option to cure this otherwise fatal disease. Retrospective data on clinical presentation, genetics, and outcome of HSCT were collected from centers in Europe, Asia, and North America for a total of 32 patients born between 1982 and 2011. Age at presentation was <4 weeks in 30 of 32 patients (94%). Grafts originated from mismatched family donors in 17 patients (55%), from matched family donors in 6 patients (19%), and from unrelated marrow or umbilical cord blood donors in 8 patients (26%). Thirteen patients received secondary or tertiary transplants. After transplantation, 21 of 31 patients were reported alive at a mean follow-up of 7.9 years (range: 0.6-23.6 years). All patients who died beyond 6 months after HSCT had persistent or recurrent agranulocytosis due to failure of donor myeloid engraftment. In the absence of conditioning, HSCT was ineffective to overcome agranulocytosis, and inclusion of myeloablative components in the conditioning regimens was required to achieve stable lymphomyeloid engraftment. In comparison with other SCID entities, considerable differences were noted regarding age at presentation, onset, and type of infectious complications, as well as the requirement of conditioning prior to HSCT. Although long-term survival is possible in the presence of mixed chimerism, high-level donor myeloid engraftment should be targeted to avoid posttransplant neutropenia.

Relevance of the eastern African coastal forest for early hominin biogeography.

The influence of climate change on hominin evolution is much debated. Two issues hamper our understanding of this process: the limited hominin fossil record, and incomplete knowledge about hominin spatial occupation of Africa. Here, we analyze the presently known hominin fossil distribution pattern and explore the potential geographic distribution of hominins between ∼4.5 and ∼2.5 Ma. We focus on assessing the relevance of the Coastal Forest of Eastern Africa (CFEA) along the Indian Ocean as a core area for early hominin evolution. Based on biogeographic-phylogeographic data we propose the coastal refuge hypothesis: the CFEA provided a refugium for early hominins in periods of variable climate and strong seasonality during eccentricity maxima. From this refuge, evolved species could disperse inland (e.g. to rift basins) via vegetated humid corridors, whenever onset of stable climate periods with low seasonality during eccentricity minima allowed expansion out of the coastal enclave. We develop a conceptual model in time and space, comparing predictions with climatic and hominin fossil records. The results imply that: 1) between ∼4.5 and 3 Ma, ongoing (mostly anagenetic) hominin evolution occurred in the CFEA, punctuated by inland dispersal events at ∼4.4, 4.2, 3.8, 3.5, and 3.2 Ma; 2) before ∼3 Ma, the Afar Basin was a (sub)core area often connected to and relatively similar to the CFEA, while other inland areas were more or less marginal for early hominin habitation; 3) after ∼3 Ma, Northern Hemisphere Glaciation exerted strong influence by causing latitudinal contraction of the CFEA, leading to habitat fragmentation, isolation of hominin populations and possible cladogenetic evolution. A major challenge for the coastal refuge model is the fact that at present, no (hominin) fossils are known from the CFEA. We consider how this can be explained, and possibly overcome with targeted search efforts. Furthermore we discuss how the model can be tested, e.g. with molecular phylogeography approaches, and used to predict new hominin fossil locations. With this study, we hope to contribute a fresh perspective to the climate-evolution debate, emphasizing the role of climatic stability, length of dry season and vegetation cover to facilitate connectivity between hominin core and marginal habitats.

Treosulfan and Fludarabine Conditioning for Hematopoietic Stem Cell Transplantation in Children with Primary Immunodeficiency: UK Experience.

We previously published results for 70 children who received conditioning with treosulfan and cyclophosphamide (n = 30) or fludarabine (n = 40) before undergoing hematopoietic stem cell transplantation (HSCT) for primary immunodeficiency (PID). Toxicity was lower and T cell chimerism was better in the patients receiving fludarabine, but cohort numbers were relatively small and follow-up was short. Here we report outcomes of 160 children who received homogeneous conditioning with treosulfan, fludarabine, and, in most cases, alemtuzumab (n = 124). The median age at transplantation was 1.36 years (range, .09 to 18.25 years). Donors included 73 matched unrelated, 54 1 to 3 antigen-mismatched unrelated, 12 matched sibling, 17 other matched family, and 4 haploidentical donors. Stem cell source was peripheral blood stem cells (PBSCs) in 70, bone marrow in 49, and cord blood in 41. Median duration of follow-up was 4.3 years (range, .8 to 9.4 years). Overall survival was 83%. No patients had veno-occlusive disease. Seventy-four patients (46%) had acute GVHD, but only 14 (9%) greater than grade II. Four patients underwent successful retransplantation for graft loss or poor immune reconstitution. Another patient experienced graft rejection and died. There was no association between T cell chimerism >95% and stem cell source, but a significant association was seen between myeloid chimerism >95% and use of PBSCs without an increased risk of significant GVHD compared with other sources. All 11 patients with severe combined immunodeficiency diagnosed at birth were alive at up to 8.7 years of follow-up. Long-term studies are needed to determine late gonadotoxic effects, and pharmacokinetic studies are needed to identify whether specific targeting is advantageous. The combination of treosulfan, fludarabine, and alemtuzumab is associated with excellent results in HSCT for PID.

Recent advances in understanding the pathogenesis and management of reticular dysgenesis.

Reticular Dysgenesis is a rare immunodeficiency which is clinically characterized by the combination of Severe Combined Immunodeficiency (SCID) with agranulocytosis and sensorineural deafness. Mutations in the gene encoding adenylate kinase 2 (AK2) were identified to cause this phenotype. In this review, we will demonstrate important clinical differences between reticular dysgenesis and other SCID entities and summarize recent concepts in the understanding of the pathophysiology of the disease and the management strategies for this difficult condition.

Adenosine Deaminase (ADA)-Deficient Severe Combined Immune Deficiency (SCID): Molecular Pathogenesis and Clinical Manifestations.

Deficiency of adenosine deaminase (ADA, EC3.5.4.4), a housekeeping enzyme of purine metabolism encoded by the Ada gene, is a cause of human severe combined immune deficiency (SCID). Numerous deleterious mutations occurring in the ADA gene have been found in patients with profound lymphopenia (T- B- NK-), thus underscoring the importance of functional purine metabolism for the development of the immune defense. While untreated ADA SCID is a fatal disorder, there are multiple life-saving therapeutic modalities to restore ADA activity and reconstitute protective immunity, including enzyme replacement therapy (ERT), allogeneic hematopoietic stem cell transplantation (HSCT) and gene therapy (GT) with autologous gene-corrected hematopoietic stem cells (HSC). We review the pathogenic mechanisms and clinical manifestations of ADA SCID.

Use of Indocyanine Green-SPY Angiography for Tracking Lymphatic Recovery After Lymphaticovenous Anastomosis.

INTRODUCTION: Lymphaticovenous anastomosis (LVA) is a surgical treatment option for patients with early stage lymphedema. To date, no ideal imaging modality exists for tracking patency of the LVA postoperatively. We hypothesize that laser angiography utilizing indocyanine green (ICG) via the SPY system (Lifecell Corp.) would be a useful methodology for assessing the patency of the LVA and lymphatic recovery postoperatively. METHODS: A prospective trial was performed on patients with stage II lymphedema who underwent LVA from 2013 to 2014 by a single surgeon. All candidates underwent preoperative and postoperative lymphatic mapping using ICG-SPY angiography. Postoperative analyses were performed at 1 month and at 9 months after surgery and assessed for patency at the site of the LVAs and for changes in lymphatic pattern. RESULTS: Five patients underwent LVA, 3 for upper extremity and 2 for lower extremity stage II lymphedema. The number of LVAs per extremity was 1 to 3 (total, 11). One month postoperative ICG-SPY angiography demonstrated flow through 9 of 11 anastomoses. Evaluation at 9 months postoperative showed improvement in lymphatic drainage. CONCLUSIONS: Indocyanine green-SPY angiography may be used to objectively evaluate the surgical outcome of LVA.

A norovirus oyster-related outbreak in a nursing home in France, January 2012.

The presence of norovirus in shellfish is a public health concern in Europe. Here, we report the results of an investigation into a norovirus gastroenteritis outbreak following a festive lunch which affected 84 (57%) residents and staff members of a nursing home in January 2012 in France. Individuals who had eaten oysters had a significantly higher risk of developing symptoms in the following 2·5 days than those who had not, the risk increasing with the amount eaten [relative risk 2·2 (1·0-4·6) and 3·3 (1·6-6·6) for 3-4 and 5-12 oysters, respectively]. In healthy individuals during those days, 29 (32%) subsequently became ill, most of whom were staff members performing activities in close contact with residents. Genogroup II noroviruses were detected in faecal samples, in a sample of uneaten oysters and in oysters from the production area. Identifying a norovirus's infectious dose may facilitate the health-related management of contaminated shellfish.

Forecasts of health care utilization related to pandemic A(H1N1)2009 influenza in the Nord-Pas-de-Calais region, France.

OBJECTIVES: To describe and evaluate the forecasts of the load that pandemic A(H1N1)2009 influenza would have on the general practitioners (GP) and hospital care systems, especially during its peak, in the Nord-Pas-de-Calais (NPDC) region, France. STUDY DESIGN: Modelling study. METHODS: The epidemic curve was modelled using an assumption of normal distribution of cases. The values for the forecast parameters were estimated from a literature review of observed data from the Southern hemisphere and French Overseas Territories, where the pandemic had already occurred. Two scenarios were considered, one realistic, the other pessimistic, enabling the authors to evaluate the 'reasonable worst case'. Forecasts were then assessed by comparing them with observed data in the NPDC region--of 4 million people. RESULTS: The realistic scenarios forecasts estimated 300,000 cases, 1500 hospitalizations, 225 intensive care units (ICU) admissions for the pandemic wave; 115 hospital beds and 45 ICU beds would be required per day during the peak. The pessimistic scenario's forecasts were 2-3 times higher than the realistic scenario's forecasts. Observed data were: 235,000 cases, 1585 hospitalizations, 58 ICU admissions; and a maximum of 11.6 ICU beds per day. CONCLUSIONS: The realistic scenario correctly estimated the temporal distribution of GP and hospitalized cases but overestimated the number of cases admitted to ICU. Obtaining more robust data for parameters estimation--particularly the rate of ICU admission among the population that the authors recommend to use--may provide better forecasts.

Optogenetically controlled inflammasome activation demonstrates two phases of cell swelling during pyroptosis.

Inflammasomes are multiprotein platforms that control caspase-1 activation, which process the inactive precursor forms of the inflammatory cytokines IL-1ß and IL-18, leading to an inflammatory type of programmed cell death called pyroptosis. Studying inflammasome-driven processes, such as pyroptosis-induced cell swelling, under controlled conditions remains challenging because the signals that activate pyroptosis also stimulate other signaling pathways. We designed an optogenetic approach using a photo-oligomerizable inflammasome core adapter protein, apoptosis-associated speck-like containing a caspase recruitment domain (ASC), to temporally and quantitatively manipulate inflammasome activation. We demonstrated that inducing the light-sensitive oligomerization of ASC was sufficient to recapitulate the classical features of inflammasomes within minutes. This system showed that there were two phases of cell swelling during pyroptosis. This approach offers avenues for biophysical investigations into the intricate nature of cellular volume control and plasma membrane rupture during cell death.

Treosulfan-based conditioning regimens for hematopoietic stem cell transplantation in children with primary immunodeficiency: United Kingdom experience.

Children with primary immunodeficiency diseases, particularly those less than 1 year of age, experience significant toxicity after hematopoietic stem cell transplantation, with busulfan- or melphalan-based conditioning. Treosulfan causes less veno-occlusive disease than busulfan and does not require pharmacokinetic monitoring. We report its use in 70 children. Children received 42 g/m(2) or 36 g/m(2) with cyclophosphamide 200 mg/kg (n = 30) or fludarabine 150 mg/m(2) (n = 40), with alemtuzumab in most. Median age at transplantation was 8.5 months (range, 1.2-175 months); 46 (66%) patients were 12 months of age or younger. Donors were as follows: matched sibling donor, 8; matched family donor, 13; haploidentical, 4; and unrelated, 45. Median follow-up was 19 months (range, 1-47 months). Overall survival was 81%, equivalent in those age less or greater than 1 year. Skin toxicity was common. Veno-occlusive disease occurred twice with cyclophosphamide. Eighteen patients (26%) had graft-versus-host disease, and only 7 (10%) greater than grade 2. Two patients rejected; 24 of 42 more than 1 year after transplantation had 100% donor chimerism. The remainder had stable mixed chimerism. T-cell chimerism was significantly better with fludarabine. Long-term follow-up is required, but in combination with fludarabine, treosulfan is a good choice of conditioning for hematopoietic stem cell transplantation in primary immunodeficiency disease.