Standardizing Randomized Controlled Trials in Celiac Disease: An International Multidisciplinary Appropriateness Study.

BACKGROUND & AIMS: There is a need to develop safe and effective pharmacologic options for the treatment of celiac disease (CeD); however, consensus on the appropriate design and configuration of randomized controlled trials (RCTs) in this population is lacking. METHODS: A 2-round modified Research and Development/University of California Los Angeles Appropriateness Method study was conducted. Eighteen gastroenterologists (adult and pediatric) and gastrointestinal pathologists voted on statements pertaining to the configuration of CeD RCTs, inclusion and exclusion criteria, gluten challenge, and trial outcomes. Two RCT designs were considered, representing the following distinct clinical scenarios for which pharmacotherapy may be used: trials incorporating a gluten challenge to simulate exposure; and trials evaluating reversal of histologic changes, despite attempted adherence to a gluten-free diet. Each statement was rated as appropriate, uncertain, or inappropriate, using a 9-point Likert scale. RESULTS: For trials evaluating prevention of relapse after gluten challenge, participants adherent to a gluten-free diet for 12 months or more with normal or near-normal-sized villi should be enrolled. Gluten challenge should be FODMAPS (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) free, and efficacy evaluated using histology with a secondary patient-reported outcome measure. For trials evaluating reversal of villus atrophy, the panel voted it appropriate to enroll participants with a baseline villus height to crypt depth ratio ≤2 and measure efficacy using a primary histologic end point. Guidance for measuring histologic, endoscopic, and patient-reported outcomes in adult and pediatric patients with CeD are provided, along with recommendations regarding the merits and limitations of different end points. CONCLUSIONS: We developed standardized recommendations for clinical trial design, eligibility criteria, outcome measures, gluten challenge, and disease evaluations for RCTs in patients with CeD.

Heterogeneity of mesenchymal cells in human amniotic membrane at term.

There is increasing interest in understanding the tissue biology of human amniotic membrane (hAM) given its applications in medicine. One cellular component is mesenchymal cells, which can be extracted, cultured and differentiated "in vitro" into various cell types. These studies show that there is heterogeneity among mesenchymal cells. The aim of this work is to study the membrane "in situ" to determine whether this cellular heterogeneity exists. The hAMs were obtained from caesarean deliveries at term and analyzed by histological techniques. Types I-III mesenchymal cells and Hofbauer were distinguished by light microscopy. Histochemically, mesenchymal cell types showed successively increasing positivity to: PAS, vimentin, fibronectin, and Concanavalin-A; VGEF, TGF-ß2, PDGF-C, FGF-2. By the semiquantitative point of view, the percentage of Type II cells was 60%, significantly higher than the other types. With transmission electron microscopy, an intermediate cell type between II-III was observed. Strong vesiculation of the rough endoplasmic reticulum (RER) with exocytosis was observed. In addition, an accumulation of a similar material to the extracellular matrix in the RER caused its dilation especially in type III cells. Some of this material acquired a globular structure. These structures were also found free in the extracellular matrix. In conclusion, the mesenchymal cells of the fibroblastic layer of the hAMs studied are heterogeneous, with some undifferentiated and others with a probably senescent fibroblastic phenotype with accumulation in their RER of fibronectin. These results may be of interest to extract mesenchymal cells from hAMs for use in regenerative medicine and to better understand the mechanisms of fetal membrane rupture.

Upper gastrointestinal endoscopic findings in celiac disease at diagnosis: A multicenter international retrospective study.

BACKGROUND: Gastroduodenal endoscopy and biopsy following positive specific serology is considered the gold standard to diagnose celiac disease (CeD) in adults. Whether upper endoscopy helps detect comorbid conditions is unknown. AIM: To investigate the prevalence of non-celiac endoscopic findings in patients in whom endoscopy was performed to confirm CeD diagnosis. METHODS: This is an observational, descriptive, multicenter, retrospective study that reports endoscopic findings obtained in adult patients enrolled in local registries from four tertiary centers. We collected data reported on first endoscopy, indicated for investigation of CeD. Diagnosis of CeD was performed by histology (≥ Marsh 2 type mucosal damage) and specific serology. Two European and one North American center included biopsy-confirmed CeD following positive serology. A fourth center (South America) included symptomatic patients undergoing endoscopy, irrespective of CeD serology. The latter cohort included a non-CeD control group. RESULTS: A total of 1328 patients (80% female; 35 years median age) were enrolled, of whom 95.6% had positive specific serology. In 135 patients, endoscopy revealed 163 abnormalities unrelated to CeD (prevalence: 10.1%). Erosive reflux esophagitis (6.4%), gastric erosions (2.0%), and suspicion of esophageal metaplasia (1.2%) were the most common findings. Biopsy-confirmed Barrett's esophagus was infrequent (0.2%). No endoscopic cancer was detected. Older patients (≥ 51 years of age) had a higher prevalence of endoscopic findings than those ≤ 50 (P < 0.01). Within the South American cohort, CeD was associated with a lower rate (8.2%) of comorbid endoscopic findings compared with controls (29.1%; P < 0.001). In the adjusted multivariate analysis of this cohort, having CeD was associated with a 72% reduction in the risk of any endoscopic abnormality (P < 0.0001), and having alarm symptoms was associated with a 37% reduction in the risk of finding at least one endoscopic lesion (P < 0.02). CONCLUSION: In this large multicenter study, young adults with positive CeD serology had few comorbid endoscopic findings. Although patients over 51 years had a high prevalence of non-CeD gastroduodenal mucosal damage, no malignancy or premalignant lesions were found.

Weight Loss Following Hepatopancreatobiliary Surgery. How Much is Too Much? A Retrospective Cohort Study.

Background & Aims. Postoperative weight loss is common following hepato-pancreato-biliary (HPB) surgical resections; however, the extent of weight loss and the association with poor outcomes have not been well described. We assessed the average percentage of weight loss and risk factors associated with sustained postoperative weight loss. Materials and Methods. We enrolled patients undergoing major HPB surgical resections from 2011-2016 at a single institution. We evaluated percent change in weight postoperatively, incidence of complications, and nutritional clinical markers at 1, 3, and 6 months postoperatively compared to preoperative baseline. We used multiple logistic regression to evaluate factors associated with significant weight loss (>10% from baseline) at 3 months from surgery. Results. Among 262 patients undergoing HPB surgery, liver surgery patients lost 2.5% of baseline weight at 3 months postoperatively but regained baseline weight by 6 months. Pancreatic surgery patients lost 7.7% at 3 months and were unable to recover their baseline weights at 6 months. Forty-three (16%) patients had major postoperative complications including abdominal abscess (5.3%) and anastomotic leak (3.8%). Patients who experienced major postoperative complications had a greater percentage weight loss at 3 months compared to those without major complications: median 11% (interquartile range (IQR): 7%-15%) vs 4% (IQR: 0%-8%), P < .001. In the multivariable analysis, major postoperative complications were associated with significant weight loss at 3 months (OR 3.39, 95% CI 1.38-8.33). Conclusions. Due to the association of weight loss and major postoperative complications, patients who experience significant weight loss (>10% from baseline) may benefit from nutritional assessment for dietary intervention.

The deleterious effects induced by an acute exposure of human skin to common air pollutants are prevented by extracts of Deschampsia antarctica.

The homeostatic and regenerative potential of the skin is critically impaired by an increasing accumulation of air pollutants in human ecosystems. These toxic compounds are frequently implicated in pathological processes such as premature cutaneous ageing, altered pigmentation and cancer. In this scenario, innovative strategies are required to tackle the effects of severe air pollution on skin function. Here we have used a Human Skin Organotypic Culture (HSOC) model to characterize the deleterious effects of an acute topic exposure of human skin to moderately high concentrations of common ambient pollutants, including As, Cd, Cr, dioxins and tobacco smoke. All these toxic compunds inflict severe damage in the tissue, activating the AHR-mediated response to xenobiotics. We have further evaluated the potential of an aqueous leaf extract of the polyextremophile plant Deschampsia antarctica (Edafence) to protect human skin against the acute exposure to toxic pollutants. Our results indicate that pre-treatment of HSOC samples with this aqueous extract conuterbalances the deleterious effects of the exposure to toxic comunds and triggers the activation of key genes invoved in the redox system and in the pro-inflammatory/wound healing response in the skin, suggesting that this natural compound might be effectively used in vivo to protect human skin routinely in different daily conditions.

A Photodynamic Tool to Promote a Sustained, ROS-Dependent Growth of Human Hair Follicles in Ex Vivo Culture.

Reactive oxygen species (ROS) may severely affect the biochemical viability of most cells. However, ROS may act also as key second messengers regulating important physiological functions in eukaryotic organisms. Of special interest is the potential role of ROS in the regulation of stem cell function and tissue homeostasis and regeneration in adult mammalian tissues. In this context, the hair follicle constitutes an excellent experimental model to study this aspect of ROS biology.Here we present a robust protocol to promote a sustained growth of ex vivo cultured human hair follicles based on the induction of a transient/modulable production of nonlethal endogenous ROS levels in the tissue through a protoporphyrin IX-dependent photodynamic procedure. The light-switchable ROS production activates hair follicle stem cell niches, induces cell proliferation, and maintains the growth/anagen phase for long time. This approach constitutes a complementary experimental tool to study the physiological roles of ROS in human tissues.

Stimulation of Stem Cell Niches and Tissue Regeneration in Mouse Skin by Switchable Protoporphyrin IX-Dependent Photogeneration of Reactive Oxygen Species In Situ.

Here, we describe a protocol to induce switchable in vivo photogeneration of endogenous reactive oxygen species (ROS) in mouse skin. This transient production of ROS in situ efficiently activates cell proliferation in stem cell niches and stimulates tissue regeneration as strongly manifested through the acceleration of burn healing and hair follicle growth processes. The protocol is based on a regulatable photodynamic treatment that treats the tissue with precursors of the endogenous photosensitizer protoporphyrin IX and further irradiates the tissue with red light under tightly controlled physicochemical parameters. Overall, this protocol constitutes an interesting experimental tool to analyze ROS biology.

Publisher Correction: Intrinsic activation of cell growth and differentiation in ex vivo cultured human hair follicles by a transient endogenous production of ROS.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Schwannoma Con Una Localización Cervical Infrecuente En Un Paciente Pediátrico: Reporte De Caso / Schwannoma With A Non-Frequent Location In Pediatric Patient. Case Report

Resumen Los schwannomas son tumores usualmente benignos, de crecimiento lento y generalmente propios de adultos. Son muy raros en la población pediátrica y su diagnóstico requiere un alto índice de sospecha clínica. Se presenta el caso de un paciente de sexo masculino de 9 años con historia de una masa cervical asintomática, sin otros antecedentes clínicos relevantes. La escisión total de la masa fue posible e histopatología confirmó el diagnóstico de schwannoma. El paciente se recuperó completamente, con excelente pronóstico. Es necesario tener presente a los schwannomas en el diagnóstico diferencial en casos de masas cervicales en pacientes pediátricos.

Abstract Schwannomas are usually benign, slow-growing tumors, usually found in adults. They are very rare in the pediatric population and their diagnosis requires a high index of clinical suspicion. We present the case of a 9-year-old male patient with a history of an asymptomatic cervical mass, with no other relevant clinical history. Total excision of the mass was possible, and histopathology confirmed the diagnosis of schwannoma. The patient recovered completely, with excellent prognosis. It is necessary to keep in mind schwannomas in the differential diagnosis in cases of cervical masses in pediatric patients.

Toward New Paradigms in the Follow Up of Adult Patients With Celiac Disease on a Gluten-Free Diet.

Gluten free diet is the only available treatment for celiac disease (CeD). Patients with CeD who do not adhere to a strict gluten-free diet (GFD) have been found to have complications involving nutritional deficiencies, increased risk of bone fractures, increased risk of mortality, and certain types of cancers. Complete removal of gluten from the diet in a patient with CeD often results in symptomatic, serologic, and histologic remission. However, strict compliance with the diet is challenging. Long-term follow-up care is needed to assure treatment compliance and positive health outcomes. Monitoring celiac specific serology, nutrient deficiencies, bone mineral density, and assessment of GFD compliance have been recommended in clinical practice. However, there is no consensus on which specific tests and how often they should be performed during the follow up. Here, we have performed a review of the literature on current strategies to follow up patients with CeD. There are new tools for monitoring adherence to the GFD which could change some paradigms in following up treated patients.

Strengthening the Chain of Survival: Cardiopulmonary Resuscitation Workshop for Caregivers of Children at Risk.

BACKGROUND: Parents and caregivers should receive training regarding pediatric cardiopulmonary resuscitation (CPR) because this knowledge improves survival. We conducted a study as part of a Patient Safety Project to improve caregivers' CPR knowledge and skills. We also aimed to improve the quality of patient care. METHODS: We performed a prospective, longitudinal study in 2013-2014 in a pediatric hospital. We enrolled the caregivers of all patients admitted with a diagnosis of an acute life-threatening event, apnea, or choking. We provided a 45-minute CPR workshop for parents at discharge and evaluated the results using a test before, immediately after, and at 1 and 3 months after the workshop. Participants also completed an evaluation survey about the CPR workshop. RESULTS: We admitted 62 patients [median age, 1 mo (0.5-2 mo)]. We provided 62 pediatric CPR workshops to 106 enrolled relatives. The median score was 5 (CI, 3-6) out of 10 at baseline, which increased to 8 (CI, 7-10) immediately after the workshop (P < 0.01). After 1 and 3 months, the median score was 8 (CI, 6-9; P < 0.01). The severity of the acute life-threatening event episode correlated with a better score (P = 0.02). The utility of the workshop scored 9.9 out of 10. CONCLUSIONS: This CPR workshop significantly increased CPR knowledge and confidence, and this was maintained up to 3 months post-training. Caregiver satisfaction was high.

Intrinsic activation of cell growth and differentiation in ex vivo cultured human hair follicles by a transient endogenous production of ROS.

The emerging variety of signalling roles for ROS in eukaryotic cells and tissues is currently a matter of intense research. Here we make use of ex vivo cultured single human hair follicles as an experimental model to demonstrate that a transient production of non-lethal endogenous ROS levels in these mini-organs promotes efficiently the entry into the growth phase (anagen). The stimulatory process implicates the specific activation of the hair follicle stem cell niche, encompassing the induction of stem cell differentiation markers (Ck15), overall cell proliferation and sustained growth of the tissue associated with expression of gen targets (Ccnd1) concomitant with the inhibition of Wnt signaling antagonists and repressors (Dkk1, Gsk3ß) of Wnt signaling. As a whole, this observation indicates that, once activated, ROS signalling is an intrinsic mechanism regulating the hair follicle stem cell niche independently of any external signal.

A role for the Tgf-ß/Bmp co-receptor Endoglin in the molecular oscillator that regulates the hair follicle cycle.

The hair follicle is a biological oscillator that alternates growth, regression, and rest phases driven by the sequential activation of the proliferation/differentiation programs of resident stem cell populations. The activation of hair follicle stem cell niches and subsequent entry into the growing phase is mainly regulated by Wnt/ß-catenin signalling, while regression and resting phases are mainly regulated by Tgf-ß/Bmp/Smad activity. A major question still unresolved is the nature of the molecular switch that dictates the coordinated transition between both signalling pathways. Here we have focused on the role of Endoglin (Eng), a key co-receptor for members of the Tgf-ß/Bmp family of growth factors. Using an Eng haploinsufficient mouse model, we report that Eng is required to maintain a correct follicle cycling pattern and for an adequate stimulation of hair follicle stem cell niches. We further report that ß-catenin binds to the Eng promoter depending on Bmp signalling. Moreover, we show that ß-catenin interacts with Smad4 in a Bmp/Eng-dependent context and both proteins act synergistically to activate Eng promoter transcription. These observations point to the existence of a growth/rest switching mechanism in the hair follicle that is based on an Eng-dependent feedback cross-talk between Wnt/ß-catenin and Bmp/Smad signals.

Prevalence of wild type ATTR assessed as myocardial uptake in bone scan in the elderly population.

BACKGROUND: Myocardial uptake of bone tracers has emerged as useful tool for the early detection of transthyretin amyloidosis (ATTR). The prevalence of wild-type ATTR (ATTRwt) in individuals remains to be established. METHODS: All whole body bone scans performed in individuals ≥ 75 years with no previous clinical suspicion of ATTR were revised in a population-based university hospital over a 7-year period (1509 studies corresponding to 1114 patients; 80.5 ±â€¯4.1 years, 65% males). Positive cardiac uptake was defined according to Perugini score as grade 2 or 3. Heart failure (HF) hospitalizations during the follow-up were obtained from regional administrative databases. RESULTS: Thirty-one patients ≥ 75 years (2.78%) showed cardiac uptake; compared with those without uptake, these patients were older (85 ±â€¯5 vs. 80 ±â€¯4, p < 0.001) and predominantly males (90% vs. 64%, p = 0.005). The prevalence of cardiac uptake was 3.88% in males and 0.77% in females, and increased with age, reaching 13.9% in males≥85 years (2.7% among females). The estimated prevalence for the European standard population ≥ 75 years was 4.15% in males, 1.03% in females and 2.59% in the general population. HF hospitalizations rates were 14% in patients without uptake and 29% in those with cardiac uptake (p = 0.034). After adjusting for age and gender, cardiac uptake was associated with a higher risk of HF hospitalization (OR 2.60, 95%CI 1.09-5.74, p = 0.022). CONCLUSIONS: Myocardial uptake in bone scan is very prevalent with ageing, mainly affects males and is associated with an increased risk of HF hospitalization. These findings reinforce ATTRwt as a relevant cause of HF in the elderly.

Photochemical, thermal, biological and long-term degradation of celecoxib in river water. Degradation products and adsorption to sediment.

Celecoxib is an anti-inflammatory drug with antibacterial activity whose fate in surface water is unknown. Thus, some assays have been conducted under forced biological, photochemical and thermal conditions, and non-forced conditions, to establish its persistence and degradation products in river water. The results suggest that celecoxib dissolved in river water is not biologically degraded while it is minimally altered after its exposure to sunlight or high temperature (70°C). Only the irradiation at 254nm promotes its complete degradation. Celecoxib is degraded about 3%, in 36 weeks, when water was kept at room temperature and the exposure to sunlight was partially limited as it happens inside a body of water. Residues were monitored by ultra-pressure liquid chromatography/quadrupole time-of-flight/mass spectrometry after solid-phase extraction; eleven degradation products were detected and the structures of nine of them were unequivocally proposed from the molecular formulae and fragmentation observed in high-resolution tandem mass spectra. The long-term transformation products under non-forced conditions were 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]benzenesulfonic acid, 4-[1-(4-sulfoaminephenyl)-3-(trifluoromethyl)-1H-pyrazol-5-yl]benzoic acid and a hydroxylated derivative. The degradation over time in presence of sediment was monitored, being slightly higher, about 4%. The adsorption equilibrium constants of celecoxib and degradation products on river sediment were estimated.

Does the Genomic Landscape of Species Divergence in Phaseolus Beans Coerce Parallel Signatures of Adaptation and Domestication?

Exploring the genomic architecture of species and populations divergence aids understanding how lineages evolve and adapt, and ultimately can show the repeatability of evolutionary processes. Yet, the genomic signatures associated with divergence are still relatively unexplored, leading to a knowledge gap on whether species divergence ultimately differs in its genetic architecture from divergence at other spatial scales (i.e., populations, ecotypes). Our goal in this research was to determine whether genomic islands of speciation are more prone to harbor within-species differentiation due to genomic features, suppressed recombination, smaller effective population size or increased drift, across repeated hierarchically nested levels of divergence. We used two species of Phaseolus beans with strong genepool and population sub-structure produced by multiple independent domestications each especially in Andean and Mesoamerican / Middle American geographies. We genotyped 22,531 GBS-derived SNP markers in 209 individuals of wild and cultivated Phaseolus vulgaris and Phaseolus lunatus. We identified six regions for species-associated divergence. Out of these divergence peaks, 21% were recovered in the four within-species between-genepool comparisons and in the five within-genepool wild-cultivated comparisons (some of the latter did retrieve genuine signatures of the well described multiple domestication syndromes). However, genomic regions with overall high relative differentiation (measured by FST) coincided with regions of low SNP density and regions of elevated delta divergence between-genepools (ΔDiv), independent of the scale of divergence. The divergence in chromosome Pv10 further coincided with a between-species pericentric inversion. These convergences suggest that shared variants are being recurrently fixed at replicated regions of the genome, and in a similar manner across different hierarchically nested levels of divergence, likely as result of genomic features that make certain regions more prone to accumulate islands of speciation and within-species divergence. In summary, neighboring signatures of speciation, adaptation and domestication in Phaseolus beans are influenced by ubiquitous genomic constrains, which may continue to fortuitously shape genomic differentiation at various others scales of divergence.

Forced and long-term degradation assays of tenoxicam, piroxicam and meloxicam in river water. Degradation products and adsorption to sediment.

The fate of the pharmaceutical drugs tenoxicam, piroxicam and meloxicam in river water is evaluated here for first time. So, biological, photochemical and thermal degradation assays have been conducted to estimate their degradation rates and know their degradation products. Results indicated that the direct sunlight irradiation, without any protection, promoted a fast degradation of the oxicams while the chemical reactions in solution were less important. The biological degradation in water was negligible except for tenoxicam in whose case its influence was scarce. When the exposition of river water to sunlight was partially limited and kept under the natural day-night cycle, as occurs inside a body of water, tenoxicam, piroxicam and meloxicam (at 2 µg L-1) were detected during a period of 15, 27 and 45 days, respectively. Residues were monitored by ultra-pressure liquid chromatography/quadrupole time-of-flight/mass spectrometry after solid-phase extraction and several degradation products were found (10 for tenoxicam, 9 for piroxicam and 7 for meloxicam) and monitored over time. Their structures were proposed from the molecular formulae and fragmentation observed in high-resolution tandem mass spectra; the nature of the transformation products found in the long-term resulted to be very variable for each oxicam. Furthermore, the degradation in presence of river sediment was also monitored over time, with some differences being noted; the adsorption coefficients of the compounds on sediment were calculated, meloxicam exhibited a higher sorption capacity. The ecotoxicity of the different compounds in aquatic ecosystems was predicted, too.

Non-celiac gluten or wheat sensitivity: It's complicated!

In the last 30 years, non-celiac gluten sensitivity (NCGS) has emerged as an intriguing and controversial topic in gastroenterology. The diagnosis of NCGS/NCWS requires a symptomatic reaction to gluten, or wheat-containing food, and remission of symptoms with gluten or wheat challenge, in patients in whom celiac disease and wheat allergy have been excluded. There have been several randomized clinical trials (RCT) addressing this issue which have produced controversial results. In this issue of Neurogastroenterology and Motility, a double-blind placebo-controlled randomized trial in patients with suspected NCGS on GFD, did not reproduce symptoms after gluten intake compared to placebo. This mini-review addresses outstanding issues related to the diagnosis of NCGS/NCWS as well as areas of interest for future studies that could explain, in part, the controversy in this area.

The Complexity of Antibody Responses Elicited against the Respiratory Syncytial Virus Glycoproteins in Hospitalized Children Younger than 2 Years.

The influence of age and maternal antibodies on the antibody responses to human respiratory syncytial virus (hRSV) glycoproteins in very young children has been a matter of controversy. Both, immaturity of the immune system at very early age and suppression of the host immune response by high level of maternal antibodies have been claimed to limit the host antibody response to virus infection and to jeopardize the use of hRSV vaccines under development in that age group. Hence, the antibody responses to the two major hRSV glycoproteins (F and G) were evaluated in children younger than 2 years, hospitalized with laboratory confirmed hRSV bronchiolitis. A strong negative correlation was found between the titre of circulating ELISA antibodies directed against either prefusion or postfusion F in the acute phase, but not age, and their fold change at convalescence. These changes correlated also with the level of circulating neutralizing antibodies in sera. As reported in adults, most neutralizing antibodies in a subset of tested sera could not be depleted with postfusion F, suggesting that they were mostly directed against prefusion-specific epitopes. In contrast, a weak negative association was found for group-specific anti-G antibodies in the acute phase and their fold change at convalescence only after correcting for the antigenic group of the infecting virus. In addition, large discrepancies were observed in some individuals between the antibody responses specific for F and G glycoproteins. These results illustrate the complexity of the anti-hRSV antibody responses in children experiencing a primary severe infection and the influence of preexisting maternal antibodies on the host response, factors that should influence hRSV serological studies as well as vaccine development.

Testing Domestication Scenarios of Lima Bean (Phaseolus lunatus L.) in Mesoamerica: Insights from Genome-Wide Genetic Markers.

Plant domestication can be seen as a long-term process that involves a complex interplay among demographic processes and evolutionary forces. Previous studies have suggested two domestication scenarios for Lima bean in Mesoamerica: two separate domestication events, one from gene pool MI in central-western Mexico and another one from gene pool MII in the area Guatemala-Costa Rica, or a single domestication from gene pool MI in central-western Mexico followed by post-domestication gene flow with wild populations. In this study we evaluated the genetic structure of the wild gene pool and tested these two competing domestication scenarios of Lima bean in Mesoamerica by applying an ABC approach to a set of genome-wide SNP markers. The results confirm the existence of three gene pools in wild Lima bean, two Mesoamerican gene pools (MI and MII) and the Andean gene pool (AI), and suggest the existence of another gene pool in central Colombia. The results indicate that although both domestication scenarios may be supported by genetic data, higher statistical support was given to the single domestication scenario in central-western Mexico followed by admixture with wild populations. Domestication would have involved strong founder effects reflected in loss of genetic diversity and increased LD levels in landraces. Genomic regions affected by selection were detected and these may harbor candidate genes related to domestication.