Scanning near-field optical microscopy measurements and simulations of regularly arranged silver nanoparticles

Silver nanoparticles on a glass substrate are experimentally investigated by aperture scanning near-field optical microscopy (a-SNOM). To understand the experimental results, finite-element-method simulations are performed building a theoretical model of the a-SNOM geometry. We systematically vary parameters like aperture size, aluminum-coating thickness, tip cone angle, and tip-surface distance and discuss their influence on the near-field enhancement. All these investigations are performed comparatively for constant-height and constant-gap scanning modes. In the end, we establish a reliable and stable optical model for simulating a-SNOM measurements, which is capable of reproducing trends observed in experimental data.

Association between Regular Vaginal Dilation and/or Sexual Activity and Long-Term Vaginal Morbidity in Cervical Cancer Survivors

PURPOSE/OBJECTIVE(S)

To evaluate the association between regular vaginal dilation and/or sexual activity and vaginal morbidity in locally advanced cervical cancer patients after definitive radiochemotherapy and image-guided adaptive brachytherapy from the EMBRACE I study.

MATERIALS/METHODS

Physician-assessed vaginal morbidity (CTCAE v.3), vaginal dilation and patient-reported sexual activity (EORTC QLQ CX24) were assessed at baseline, every 3 months in the 1st year, every 6 months in the 2nd and 3rd year and yearly thereafter. For this longitudinal analysis, a subgroup of patients was selected with at least 3 follow-ups with information on vaginal dilation and/or sexual activity. Vaginal penetration summarized either the use of vaginal dilators or sexual activity or both. Regular vaginal penetration was defined if reported in ≥50%, infrequent if reported in <50% and absent if reported in 0% of follow-ups. Actuarial estimates of vaginal morbidity were calculated with Kaplan-Meier method and included the individual symptoms: vaginal dryness, stenosis, mucositis and bleeding. Group comparisons were evaluated with the log-rank test.

RESULTS

The EMBRACE I study included 1416 patients overall (2008-2015); the subgroup of patients for this longitudinal evaluation consists of 882 patients, with a median follow-up of 60 months (IQR 47-77). Of those, 565 (64%) reported regular, 205 (23%) infrequent and 112 (13%) no penetration. Reporting regular penetration was associated with a significantly lower risk of vaginal stenosis G≥2 of 23% at 5 years, compared to reporting of infrequent (37%) and no penetration (36%, p≤0.001). However, reporting regular penetration was associated with a significantly higher risk for vaginal dryness G≥1 (72% vs. 69% vs. 62%, respectively, p = 0.038) and bleeding G≥1 (61% vs. 40% vs. 25%, respectively, p≤0.001). No associations were seen for G≥1 vaginal stenosis, G≥2 dryness, G≥2 bleeding and G≥1/G≥2 mucositis.

CONCLUSION

Regular penetration (defined as vaginal dilation and/or sexual activity) was associated with lower risk for vaginal stenosis G≥2, but higher risk for vaginal dryness G≥1 and bleeding G≥1. Mild vaginal dryness seems to become apparent in particular for patients experiencing vaginal penetration. Minor vaginal blood loss during dilation and/or sexual activity is commonly reported by patients, resulting from atrophy of the vaginal mucosa and/or telangiectasia. While both of these G≥1 symptoms can be managed with lubricants, moisturizer and/or hormonal replacement therapy, G≥2 vaginal stenosis represents an irreversible fibrotic adverse event that can cause dyspareunia in many cancer patients. These long-term data support clinical recommendations for dilation and/or sexual activity after radiotherapy.

Litigations in orthopedics and trauma surgery: reasons, dynamics, and profiles

BACKGROUND

In recent literature, the increasing number of medical litigations, both in terms of the number of cases being filed and the substantive costs associated with lawsuits, has been described. This study aims to provide an overview of the profile of litigation for orthopedic and trauma surgery to describe the differences and the development of the number of cases over time.

PATIENTS AND MATERIALS

A retrospective review of all litigations between 2000 and 2017 was conducted using the institutional legal database. The causes of litigation were documented and classified into seven major categories. In addition to plaintiff characteristics, the litigation outcomes and the differences between emergency and elective surgery were analyzed.

RESULTS

A total of 230 cases were evaluated. The mean age of the plaintiffs was 44.6 ± 20.1 years, and 56.8% were female. The main reasons for litigation were claimed inappropriate management (46.1%), misdiagnosis (22.6), and poor nursing care (8.3%). Significantly more litigations were filed against surgeons of the orthopedic subspecialty compared with trauma surgeons (78%; p ≤ 0.0001). There were significantly fewer litigations per 1000 cases filed overall in 2009-2017 (65% less; p = 0.003) than in 2000-2008.

CONCLUSION

Our results could not confirm the often-stated trend of having more litigations against orthopedic and trauma surgeons. Although the absolute numbers increased, the number of litigations per 1000 patients treated declined. Patients who underwent elective surgery were more likely to file complaints than emergency patients.

Stability of self-reported psychopathic traits in at-risk adolescents in youth welfare and juvenile justice institutions

BACKGROUND

The purpose of this study was to evaluate the self-reported stability of psychopathic traits in adolescents in residential care (both child welfare and juvenile justice placed juveniles) and potential influencing factors.

METHODS

We applied the Youth Psychopathic traits Inventory (YPI) in a sample of 162 adolescents (M = 15.0 years, SD = 1.3) over a mean time interval of 11 months (min. 6, max. 21 months, SD = 3.14).

RESULTS

There was no significant difference in YPI total score nor in the three underlying dimensions Grandiose-Manipulative (GM), Callous-Unemotional (CU), and Impulsive-Irresponsible (II) between t1 and t2. Furthermore, approximately 70% of the adolescents showed no clinically significant reliable change on the YPI total score (as measured with the reliable change index), 15% improved, 15% deteriorated. The strongest predictor for psychopathic traits at t2 were psychopathic traits at t1. Additional predictors for higher levels of general psychopathic traits was male sex, for CU-traits male sex and lower levels of internalizing mental health problems, and for II-traits higher levels of externalizing mental health problems. Generally, the three reliable change groups (increase, no change, decrease) did not seemed to differ on relevant factors.

CONCLUSIONS

Our results add to the findings that psychopathic traits are relatively stable in this at-risk group over approximately a 1-year time interval. Research with a longer follow-up time and more time points is warranted to better interpret these results.

POS1200 DIFFERENCES BETWEEN THE FIRST AND THE SECOND WAVE OF SARS-COV-2 INFECTION IN PATIENTS WITH IMMUNE-MEDIATED INFLAMMATORY DISEASES IN ARGENTINA: DATA FROM THE SAR-COVID REGISTRY

Background

In Argentina we have witnessed two COVID 19 waves between 2020 and 2021. The first wave occurred during the spring of 2020 and it was related to the wild type of the virus, the second occurred during the fall/winter of 2021 when the gamma variant showed a clear predominance. During the first wave, patient with rheumatic diseases showed a higher frequency of hospitalization and mortality (4% vs 0.26%) when compared to the general population1; at that time, however, vaccination was not yet available.

Objectives

To compare sociodemographic and disease characteristics, course and outcomes of SARS-CoV-2 infection in patients with immune-mediated/autoinflammatory diseases (IMADs) during the first and second waves in Argentina.

Methods

SAR-COVID is a national, multicenter, longitudinal and observational registry, in which patients ≥18 years of age, with a diagnosis of a rheumatic disease who had confirmed SARS-CoV-2 infection (RT-PCR or positive serology) were consecutively included since August 2020. For the purpose of this report, only patients with IMADs who had SARS-CoV-2 infection during the first wave (defined as cases occurred between March 2020 and March 2021) and the second wave (cases occurred between April and August 2021) were examined. Sociodemographic characteristics, disease diagnosis and activity, comorbidities, immunosuppressive treatment and COVID 19 clinical characteristics, complications and outcomes: hospitalization, intensive care unit (ICU) admission, use of mechanical ventilation and death were compared among groups. Descriptive statistical analysis was performed. Variables were compared with Chi squared test and Student T test or Mann Whitney test. Multivariable logistic regression models with forward and backward selection method, using hospitalization, ICU admission and death as dependent variables were carried out.

Results

A total of 1777 patients were included, 1342 from the first wave and 435 of the second one. Patients had a mean (SD) age of 50.7 (14.2) years and 81% were female. Both groups of patients were similar in terms of socio-demographic features, disease diagnosis, disease activity, the use of glucocorticoids ≥ 10 mg/day and the immunosuppressive drugs (Table 1 below). Patients infected during the first wave have higher frequency of comorbidities (49% vs 41%; p= 0.004). Hospitalizations due to COVID 19 (31% vs 20%; p <0.001) and ICU admissions (9% vs 5%; p= 0.009) were higher during the first wave. No differences in the use of mechanical ventilation (16% vs 16%; p= 0.97) nor in the mortality rate (5% vs 4%; p= 0.41) were observed. In the multivariable analysis, after adjusting for demographics, clinical features and immunosuppressive treatment, patients infected during the second wave were 40% less likely to be hospitalized (OR= 0.6, IC95% 0.4-0.8) and to be admitted to the ICU (OR= 0.6, IC95% 0.3-0.9).

Table 1.Variable (% or Mean – SD)First wave(n=1342)Second wave(n=435)p ValueFemale gender81800.7Age (years)51.0 (14.5)50.0 (13.3)0.2Disease diagnosis Rheumatoid arthritis46461 Ankylosing spondylitis10110.8 Systemic lupus erythematosus171850.9 Systemic Scleroderma551 Sjögren´s syndrome650.7 Inflammatory myopathies330.5 Vasculitis430.4Disease activity High430.5Use of immune modulatorsDMARDcs53560.2DMARDts460.1DMARDb82821Use of glucocorticoids ≥10 mg12120.9Comorbidities49410.004

Conclusion

The impact of COVID 19 in Argentina, in terms of mortality in patients with IMADs was still higher compared to the general population during the second wave. However, the frequency of hospitalizations and ICU admissions was lower. These findings could be explained by the introduction of the SARS COV 2 vaccination and, probably, by the cumulative knowledge and management improvement of this infection among physicians.

References

[1]Isnardi CA et al. Epidemiology and outcomes of patients with rheumatic diseases and SARS-COV-2 infection: data from the argentinean SAR-COVID Registry. Ann Rheum Dis, 2021, suppl 1, 887.

Disclosure of Interests

None declared

POS0707 POTENTIAL USE OF BELIMUMAB IN LUPUS PATIENTS FROM ARGENTINE COHORT ACCORDING DISEASE ACTIVITY STATE

Background

The goal of targeted treatment in patients with Systemic Lupus Erythematosus (SLE) is to achieve clinical remission or low disease activity, with the best quality of life, low damage rates and better survival 1-4. RELESSAR is a multicenter, cross-sectional study registry of ≥18 years SLE (ACR 97) patients 5.

Objectives

To describe demographic, clinical characteristics and treatments in SLE patients according to disease activity state. To evaluate the proportion of SLE and refractory SLE patients that are potentially candidates for Belimumab treatment (Active SLE despite standard treatment including increased acDNA autoantibodies and low complement).

Methods

We evaluated demographic and clinical data, treatments, score of damage (SLICC), activity (SLEDAI) and comorbidity (Charlson), hospital admissions and severe infections. The patients were compared according to disease activity: remission (SLEDAI = 0 and without corticosteroids), low disease activity (LDA, SLEDAI> 0 and ≤4 and without corticosteroids) and non-optimal control (SLEDAI> 4 and any dose of corticosteroids). Refractory SLE was defined according to Rituximab (RTX) use, non-response to cyclophosphamide or two or more immunosuppressant or splenectomized patients. Potential use of Belimumab according approved prescription in Argentina was analyzed.

Results

Overall, 1277 patients were analyzed: 299 (23.4%) were in remission, 162 (12.7%) in LDA and 816 (63.9%) with non-optimal control of the disease.

Patients in non-optimal control group were younger, less frequently female and they showed less time of disease and lower socioeconomic status (p < 0.001). They were also more prevalent mestizos (p= 0.004), had higher SLEDAI and SLICC indexes (p <0.001) and higher use of immunosuppressant therapy (p <0.001). There was no difference regarding biologic treatment (RTX p= 0.547 and Belimumab p= 0.08). This group had higher proportion of hospital admissions and severe infections (p<0.001, respectively).

Two hundred and one SLE patients fulfilled the use of Belimumab prescription criteria but only 45/201 patients (22,3%) received it in the last visit. Malar rash was the only clinical variable associated with the use of Belimumab (72.7% vs 29.8% p= 0.005).

Seventy-six patients classified as refractory SLE (15.7%) and 56/76 (75.7%) never received Belimumab. Patients on Belimumab therapy were associated to treatment with lower doses of corticoids (p= 0.018) and lower rate of hospital admission caused by SLE flare (p= 0.027).

Conclusion

A high percentage of patients had uncontrolled disease upon entry into the registry and were potential candidates for treatment with Belimumab. The patients who received biologic treatment showed the benefit of requiring fewer doses of corticosteroids and having a lower rate of hospitalizations.

References

[1]Mok CC. Treat-to-target in systemic lupus erythematosus: Are we there yet? Expert Rev Clin Pharmacol. 2016;9(5).

[2]Morand EF, Mosca M. Treat to target, remission and low disease activity in SLE. Vol. 31, Best Practice and Research: Clinical Rheumatology. 2017.

[3]Golder V, Tsang-A-Sjoe MWP. Treatment targets in SLE: Remission and low disease activity state. Rheumatol (United Kingdom). 2020;59.

[4]Ruiz-Irastorza G, Bertsias G. Treating systemic lupus erythematosus in the 21st century: new drugs and new perspectives on old drugs. Vol. 59, Rheumatology (United Kingdom). 2021.

[5]Hochberg MC. Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus. Arthritis Rheum [Internet]. 1997;40(9):1725. Available from: http://www.ncbi.nlm.nih.gov/pubmed/9324032

Disclosure of Interests

Rosana Quintana: None declared, Lucila Garcia: None declared, Paula Alba: None declared, Susana Roverano: None declared, Analia Alvarez: None declared, Cesar Graf: None declared, Cecilia Pisoni: None declared, Alberto Spindler: None declared, Catalina Gomez: None declared, Heber Matias Figueredo: None declared, Silvia Papasidero: None declared, Raul Horacio Paniego: None declared, Maria DeLaVega: None declared, Emma Estela Civit De Garignani: None declared, Luciana Gonzalez Lucero: None declared, Victoria Martire: None declared, Rodrigo Águila Maldonado: None declared, Sergio Gordon: None declared, Carla Gobbi: None declared, Romina Nieto: None declared, Gretel Rausch: None declared, Vanina Góngora: None declared, Maria Agustina D´Amico: None declared, Diana Dubinsky: None declared, Alberto Omar Orden: None declared, Johana Zacariaz: None declared, Julia Romero: None declared, Mariana Alejandra Pera: None declared, Oscar Rillo: None declared, Roberto Baez: None declared, Valeria Arturi: None declared, Andrea Gonzalez: None declared, Florencia Vivero: None declared, Marcela Schmid: None declared, Victor Caputo: None declared, Maria Silvia Larroude: None declared, Graciela Gomez: None declared, Graciela Rodriguez: None declared, Josefina Marin: None declared, Maria Victoria Collado: None declared, Marisa Jorfen: None declared, Zaida Bedran: None declared, Judith Sarano: None declared, David Zelaya: None declared, MONICA SACNUN: None declared, Pablo Finucci: None declared, Romina Rojas Tessel: None declared, Maria Emilia Sattler: None declared, MAXIMILIANO MACHADO ESCOBAR: None declared, Pablo Astesana: None declared, Ursula Vanesa Paris: None declared, Alberto Allievi: None declared, Juan Manuel Vandale: None declared, Bernardo Pons-Estel: None declared, Guillermo Pons-Estel: None declared, Mercedes García Grant/research support from: GSK grant

Performance of a targeted cell-free DNA prenatal test for 22q11.2 deletion in a large clinical cohort

OBJECTIVE

22q11.2 deletion is more common than trisomies 18 and 13 combined, yet no routine approach to prenatal screening for this microdeletion has been established. This study evaluated the clinical sensitivity and specificity of a targeted cell-free DNA (cfDNA) test to screen for fetal 22q11.2 deletion in a large cohort, using blinded analysis of prospectively enrolled pregnancies and stored clinical samples.

METHODS

In order to ensure that the analysis included a meaningful number of cases with fetal 22q11.2 deletion, maternal plasma samples were obtained by prospective, multicenter enrolment of pregnancies with a fetal cardiac abnormality and from stored clinical samples from a research sample bank. Fetal genetic status, as evaluated by microarray analysis, karyotyping with fluorescence in-situ hybridization or a comparable test, was available for all cases. Samples were processed as described previously for the Harmony prenatal test, with the addition of DANSR (Digital Analysis of Selected Regions) assays targeting the 3.0-Mb region of 22q11.2 associated with 22q11.2 deletion syndrome. Operators were blinded to fetal genetic status. Sensitivity and specificity of the cfDNA test for 22q11.2 deletion were calculated based on concordance between the cfDNA result and fetal genotype.

RESULTS

The final study group consisted of 735 clinical samples, including 358 from prospectively enrolled pregnancies and 377 stored clinical samples. Of 46 maternal plasma samples from pregnancies with a 22q11.2 deletion, ranging in size from 1.25 to 3.25 Mb, 32 had a cfDNA result indicating a high probability of 22q11.2 deletion (sensitivity, 69.6% (95% CI, 55.2-80.9%)). All 689 maternal plasma samples without a 22q11.2 deletion were classified correctly by the cfDNA test as having no evidence of a 22q11.2 deletion (specificity, 100% (95% CI, 99.5-100%)).

CONCLUSIONS

The results of this large-scale prospective clinical evaluation of the sensitivity and specificity of a targeted cfDNA test for fetal 22q11.2 deletion demonstrate that this test can detect the common and smaller, nested 22q11.2 deletions with a low (0-0.5%) false-positive rate. Although the positive predictive value (PPV) observed in this study population was 100%, the expected PPV in the general pregnant population is estimated to be 12.2% at 99.5% specificity and 41.1% at 99.9% specificity. The use of this cfDNA test to screen for 22q11.2 deletion could enhance identification of pregnancies at risk for 22q11.2 deletion syndrome without significantly increasing the likelihood of maternal anxiety and unnecessary invasive procedures related to a false-positive result. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Primary melanoma of the bladder: a case report and review of the literature

OBJECTIVE

Primary bladder melanomas are rare and aggressive neoplasms. We herein described a new case and performed a review of the literature.

PATIENTS AND METHODS

We present the case of a 81-year-old woman with a primary mucosal melanoma of the bladder after a history of acral melanoma (KRAS mutated) and lentigo maligna of the forehead. Using PubMed, we found that in literature 38 cases were described.

RESULTS

In our patients, during a transurethral resection (TURBT), two bladder lesions were detected. The histologic exam revealed a malignant melanoma, Mib1/ki67: 10-12%, PDL1 <1%. No BRAF, NRAS or KRAS mutations were detected. She subsequently underwent a transurethral revision of the trigone and a partial cystectomy of the dome with bilateral pelvic lymph node dissection. Microscopical findings showed a residual 5 mm non-muscle-invasive melanoma of the bladder, with negativity of the surgical margins and of the 17 pelvic lymph nodes. No adjuvant treatment was proposed. To date the patient is disease-free.

CONCLUSIONS

Primary bladder melanoma carries a poor prognosis and poses a therapeutic challenge to clinicians who manage patients with this rare condition. In our experience the multidisciplinary approach for the diagnosis and management of this rare cancer is mandatory.

Folding Dynamics of DNA G-Quadruplexes Probed by Millisecond Temperature Jump Circular Dichroism

G-quadruplexes play important roles in cellular regulatory functions, but despite significant experimental and theoretical efforts, their folding mechanisms remain poorly understood. In this context, we developed a T-jump experiment to access the thermal denaturation and renaturation dynamics of short intramolecular G-quadruplexes in vitro, on the time scale of a few hundred milliseconds. With this new setup, we compared the thermal denaturation and renaturation kinetics of three antiparallel topologies made of the human telomeric sequences d[(5'-GGG(TTAGGG)₃-3']/Na⁺ and d[5'-AGGG(TTAGGG)₃-3']/Na⁺ and the thrombin-binding aptamer sequence d[5'-GGTTGGTGTGGTTGG-3']/K⁺, with those of the parallel topology made of the human CEB25 minisatellite d[5'-AAGGGTGGGTGTAAGTGTGGGTGGGT-3']/Na⁺. In all cases, exponential kinetics of the order of several hundred milliseconds were observed. Measurements performed for different initial temperatures revealed distinct denaturation and renaturation dynamics, ruling out a simple two-state mechanism. The parallel topology, in which all guanines adopt an anti conformation, displays much slower dynamics than antiparallel topologies associated with very low activation barriers. This behavior can be explained by the constrained conformational space due to the presence of the single-base propeller loops that likely hinders the movement of the coiled DNA strand and reduces the contribution of the entropy during the renaturation process at high temperatures.

Changes in Circulating Stem and Progenitor Cell Numbers Following Acute Exercise in Healthy Human Subjects: a Systematic Review and Meta-analysis

Despite of the increasing number of investigations on the effects of acute exercise on circulating stem and progenitor cell (SC) numbers, and in particular on respective subgroups, i.e. endothelial (ESC), hematopoietic (HSC), and mesenchymal (MSC) stem and progenitor cells, a consensus regarding mechanisms and extent of these effects is still missing. The aim of this meta-analysis was to systematically evaluate the overall-effects of acute exercise on the different SC-subgroups and investigate possible subject- and intervention-dependent factors affecting the extent of SC-mobilization in healthy humans. Trials assessing SC numbers before and at least one timepoint after acute exercise, were identified in a systematic computerized search. Compared to baseline, numbers were significantly increased for early and non-specified SCs (enSCs) until up to 0.5 h after exercise (0–5 min: +0.64 [Standardized difference in means], p < 0.001; 6–20 min: +0.42, p < 0.001; 0.5 h: +0.29, p = 0.049), for ESCs until 12–48 h after exercise (0–5 min: +0.66, p < 0.001; 6–20 min: +0.43 p < 0.001; 0.5 h: +0.43, p = 0.002; 1 h: +0.58, p = 0.001; 2 h: +0.50, p = 0.002; 3–8 h: +0.70, p < 0.001; 12–48 h: +0.38, p = 0.003) and for HSCs at 0–5 min (+ 0.47, p < 0.001) and at 3 h after exercise (+ 0.68, p < 0.001). Sex, intensity and duration of the intervention had generally no influence. The extent and kinetics of the exercise-induced mobilization of SCs differ between SC-subpopulations. However, also definitions of SC-subpopulations are non-uniform. Therefore, finding a consensus with a clear definition of cell surface markers defining ESCs, HSCs and MSCs is a first prerequisite for understanding this important topic.

Genotype-by-environment interactions at the trait level and total merit index level for milk production and functional traits in Brown Swiss cattle

The production environments of the German-Austrian Brown Swiss population show a wide range due to differences in topography, landscapes, local climates, and different farm management systems. Extensive production systems such as organic farming have become increasingly popular in recent decades because of interest in sustainability and consumer preferences. Compared with conventional farmers, organic farmers put more weight on fitness traits. Besides the official total merit index (TMI), a selection index applying relative economic weights (REWs) suitable for organic production systems is provided for Brown Swiss cattle in Germany. The aim of the study was to investigate genotype-by-environment interactions (GxE) for milk production traits and functional traits (including longevity, fertility traits, and calving traits) in a sample of the German-Austrian Brown Swiss population housed in Baden-Wuerttemberg (southern Germany) by applying bivariate and random regression sire models. For bivariate analyses, the production environment was binary classified by farm management system (organic and conventional) and altitude of farm location (above or below 800 m above sea level (ASL)). Milk energy yields (MEY) obtained from herd effects were used as continuously scaled environmental descriptor in the reaction norm approach. The TMIs for sires were calculated based on breeding values estimated with different models and environment-specific REWs to determine possible GxE at TMI levels and rerankings of sires. In bivariate analyses, genetic correlations at the trait level were high and ranged from r_g = 0.99 (calving to first insemination, cystic ovaries, and maternal stillbirth rate) to r_g = 0.79 (first insemination to conception for altitude). Except for the latter, no severe GxE were found at the trait level using the bivariate models. Fat yield was the only trait showing minor GxE in the reaction norm model approach. Investigating the environmental sensitivity at the TMI level revealed rank correlations between the different environment-specific TMIs that were close to unity, implying no severe reranking effects. The results show no need to account for different environments in Brown Swiss cattle breeding programs.

Mapping genes for phosphorus utilization and correlated traits using a 4k SNP linkage map in Japanese quail (Coturnix japonica)

A large F2 cross with 920 Japanese quail was used to map QTL for phosphorus utilization, calcium utilization, feed per gain and body weight gain. In addition, four bone ash traits were included, because it is known that they are genetically correlated with the focal trait of phosphorus utilization. Trait recording was done at the juvenile stage of the birds. The individuals were genotyped genome-wide for about 4k SNPs and a linkage map constructed, which agreed well with the reference genome. QTL linkage mapping was performed using multimarker regression analysis in a line cross model. Single marker association mapping was done within the mapped QTL regions. The results revealed several genome-wide significant QTL. For the focal trait phosphorus utilization, a QTL on chromosome CJA3 could be detected by linkage mapping, which was substantiated by the results of the SNP association mapping. Four candidate genes were identified for this QTL, which should be investigated in future functional studies. Some overlap of QTL regions for different traits was detected, which is in agreement with the corresponding genetic correlations. It seems that all traits investigated are polygenic in nature with some significant QTL and probably many other small-effect QTL that were not detectable in this study.