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Gregory D Wiens - One of the best experts on this subject based on the ideXlab platform.
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identification of single nucleotide polymorphism markers associated with bacterial cold water disease resistance and Spleen Size in rainbow trout
Frontiers in Genetics, 2015Co-Authors: Sixin Liu, Roger L Vallejo, Yniv Palti, David P Marancik, Guangtu Gao, Alvaro G Hernandez, Gregory D WiensAbstract:Bacterial cold water disease (BCWD) is one of the frequent causes of elevated mortality in salmonid aquaculture. Previously, we identified and validated microsatellites on chromosome Omy19 associated with QTL (quantitative trait loci) for BCWD resistance and Spleen Size in rainbow trout. Recently, SNPs (single nucleotide polymorphism) have become the markers of choice for genetic analyses in rainbow trout as they are highly abundant, cost-effective and are amenable for high throughput genotyping. The objective of this study was to identify SNP markers associated with BCWD resistance and Spleen Size using both genome-wide association studies (GWAS) and linkage-based QTL mapping approaches. A total of 298 offspring from the two half-sib families used in our previous study to validate the significant BCWD QTL on chromosome Omy19 were genotyped with RAD-seq (restriction-site-associated DNA sequencing), and 7,849 informative SNPs were identified. Based on GWAS, 18 SNPs associated with BCWD resistance and 20 SNPs associated with Spleen Size were identified. Linkage-based QTL mapping revealed three significant QTL for BCWD resistance. In addition to the previously validated dam-derived QTL on chromosome Omy19, two significant BCWD QTL derived from the sires were identified on chromosomes Omy8 and Omy25, respectively. A sire-derived significant QTL for Spleen Size on chromosome Omy2 was detected. The SNP markers reported in this study will facilitate fine mapping to identify positional candidate genes for BCWD resistance in rainbow trout.
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validation of linked qtl for bacterial cold water disease resistance and Spleen Size on rainbow trout chromosome omy19
Aquaculture, 2014Co-Authors: Roger L Vallejo, Yniv Palti, David P Marancik, Gregory D WiensAbstract:Abstract Bacterial cold water disease (BCWD) is caused by infection with Flavobacterium psychrophilum , and outbreaks cause significant economic losses in salmonid aquaculture. Previously, we identified a major QTL for BCWD resistance on rainbow trout chromosome Omy19 as well as a QTL for Spleen Size (SPLW = Spleen weight and SPLI = Spleen index) which in naive fish is a surrogate indicator of BCWD resistance. The objective of this study was to validate the BCWD resistance and Spleen Size QTL in a subsequent generation and investigate whether the correlation between BCWD resistance and Spleen Size loci on Omy19 was due to close linkage or pleiotropy. We designed four full-sib matings whose offspring were evaluated for BCWD resistance, body weight, SPLW and SPLI. A total of 800 offspring were genotyped with seven microsatellite markers from Omy19. Our analyses confirmed the presence of QTL for BCWD and Spleen Size on Omy19. Our findings also suggest that BCWD resistance and Spleen Size are not influenced by a single pleiotropic QTL on Omy19 as the QTL were separately inherited in the families studied. These data increase our understanding of the genetic basis of rainbow trout BCWD resistance.
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assessment of genetic correlation between bacterial cold water disease resistance and Spleen index in a domesticated population of rainbow trout identification of qtl on chromosome omy19
PLOS ONE, 2013Co-Authors: Gregory D Wiens, Roger L Vallejo, Timothy D Leeds, Yniv Palti, Sima Hadidi, Jason P Evenhuis, Timothy J Welch, Caird E RexroadAbstract:Selective breeding of animals for increased disease resistance is an effective strategy to reduce mortality in aquaculture. However, implementation of selective breeding programs is limited by an incomplete understanding of host resistance traits. We previously reported results of a rainbow trout selection program that demonstrated increased survival following challenge with Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD). Mechanistic study of disease resistance identified a positive phenotypic correlation between post-challenge survival and Spleen somatic-index (SI). Herein, we investigated the hypothesis of a genetic correlation between the two traits influenced by colocalizing QTL. We evaluated the inheritance and calculated the genetic correlation in five year-classes of odd- and even-year breeding lines. A total of 322 pedigreed families (n = 25,369 fish) were measured for disease resistance, and 251 families (n = 5,645 fish) were evaluated for SI. Spleen index was moderately heritable in both even-year (h(2) = 0.56±0.18) and odd-year (h(2) = 0.60±0.15) lines. A significant genetic correlation between SI and BCWD resistance was observed in the even-year line (rg = 0.45±0.20, P = 0.03) but not in the odd-year line (rg = 0.16±0.12, P = 0.19). Complex segregation analyses of the even-year line provided evidence of genes with major effect on SI, and a genome scan of a single family, 2008132, detected three significant QTL on chromosomes Omy19, 16 and 5, in addition to ten suggestive QTL. A separate chromosome scan for disease resistance in family 2008132 identified a significant BCWD QTL on Omy19 that was associated with time to death and percent survival. In family 2008132, Omy19 microsatellite alleles that associated with higher disease resistance also associated with increased Spleen Size raising the hypothesis that closely linked QTL contribute to the correlation between these traits. To our knowledge, this is the first estimation of Spleen Size heritability and evidence for genetic linkage with specific disease resistance in a teleost fish.
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Spleen Size predicts resistance of rainbow trout to flavobacterium psychrophilum challenge
Journal of Immunology, 2008Co-Authors: Sima Hadidi, Timothy J Welch, Gavin W Glenney, Jeffrey T Silverstein, Gregory D WiensAbstract:Selective breeding of animals for increased innate resistance offers an attractive strategy to control disease in agriculture. However, this approach is limited by an incomplete knowledge of the heritability, duration, and mechanism(s) of resistance, as well as the impact of selection on the immune response to unrelated pathogens. Herein, as part of a rainbow trout broodstock improvement program, we evaluated factors involved in resistance against a bacterial disease agent, Flavobacterium psychrophilum. In 2005, 71 full-sibling crosses, weighing an average of 2.4 g, were screened, and resistant and susceptible crosses were identified. Naive cohorts were evaluated at 10 and 800 g in Size, and most maintained their original relative resistant or susceptible phenotypes, indicating that these traits were stable as Size increased >300-fold. During the course of these studies, we observed that the normalized Spleen weights of the resistant fish crosses were greater than those of the susceptible fish crosses. To test for direct association, we determined the Spleen-somatic index of 103 fish crosses; created high, medium, and low Spleen-index groups; and determined survival following challenge with F. psychrophilum or Yersinia ruckeri. Consistent with our previous observations, trout with larger Spleen indices were significantly more resistant to F. psychrophilum challenge; however, this result was pathogen-specific, as there was no correlation of Spleen Size with survival following Y. ruckeri challenge. To our knowledge, this is the first report of a positive association between Spleen Size and disease resistance in a teleost fish. Further evaluation of Spleen index as an indirect measure of disease resistance is warranted.
Eiji Tanaka - One of the best experts on this subject based on the ideXlab platform.
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liver stiffness Spleen Size to platelet ratio risk score identifies esophageal varices in japanese patients with chronic hepatitis c
Hepatology Research, 2016Co-Authors: Soichiro Shibata, Satoru Joshita, Takeji Umemura, Tomoo Yamazaki, Naoyuki Fujimori, Yuki Ichikawa, Michiharu Komatsu, Akihiro Matsumoto, Takefumi Kimura, Eiji TanakaAbstract:AIM Non-invasive methods are needed to identify esophageal varices (EV) in patients with chronic liver disease. To this end, we evaluated liver stiffness (LS)-Spleen diameter-to-platelet ratio risk score (LSPS) in predicting EV among Japanese chronic hepatitis C patients. METHODS A total of 99 patients with chronic hepatitis C who had undergone endoscopy, LS measurement and ultrasonography between 2013 and 2014 were enrolled. Clinical data were compared with those for other non-invasive markers (platelet count, aspartate aminotransferase-to-platelet ratio, FIB-4 index and platelet-to-Spleen ratio), Spleen Size, LS and controlled attenuation parameter. Diagnostic applicability was assessed by the area under the receiver-operator curve (AUC) and predictive values along with multivariate logistic regression. RESULTS LSPS was significantly correlated to the grade of EV (ρ = 0.617, P < 0.001) and was superior to the other non-invasive indices for determination of EV. LSPS was independently associated with EV by multivariate logistic regression analysis (odds ratio, 3.079; 95% confidence interval [CI], 2.137-4.438; P < 0.001). The cut-off value of LSPS for EV was 0.7, for which the AUC, sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 0.928 (95% CI, 0.876-0.980), 86.3%, 89.6%, 70.4%, 95.8% and 88.9%, respectively. CONCLUSION LSPS may also identify EV in patients with chronic hepatitis C in Japan. The clinical values of LSPS for EV risk merit further validation in larger prospective studies.
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liver stiffness Spleen Size to platelet ratio risk score detects esophageal varices in chronic liver disease
SpringerPlus, 2016Co-Authors: Soichiro Shibata, Satoru Joshita, Takeji Umemura, Tomoo Yamazaki, Naoyuki Fujimori, Yuki Ichikawa, Michiharu Komatsu, Akihiro Matsumoto, Eiji TanakaAbstract:Background Noninvasive markers are needed to identify esophageal varices (EV) in patients with chronic liver disease (CLD). Recently, liver stiffness (LS)-Spleen Size-to-platelet ratio risk score (LSPS) has been shown to predict EV in patients with chronic hepatitis C. The aim of this study was to validate the clinical value of LSPS for EV detection and identification of high risk EV in Japanese patients with CLD.
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liver stiffness Spleen Size to platelet ratio risk score detects esophageal varices in chronic liver disease
SpringerPlus, 2016Co-Authors: Soichiro Shibata, Satoru Joshita, Takeji Umemura, Tomoo Yamazaki, Naoyuki Fujimori, Yuki Ichikawa, Michiharu Komatsu, Akihiro Matsumoto, Eiji TanakaAbstract:Noninvasive markers are needed to identify esophageal varices (EV) in patients with chronic liver disease (CLD). Recently, liver stiffness (LS)-Spleen Size-to-platelet ratio risk score (LSPS) has been shown to predict EV in patients with chronic hepatitis C. The aim of this study was to validate the clinical value of LSPS for EV detection and identification of high risk EV in Japanese patients with CLD. A total of 230 patients with CLD who had undergone endoscopy, LS measurement, and ultrasonography between 2013 and 2015 were enrolled. The relationships between clinical data and LSPS were compared with those for other noninvasive markers (aspartate aminotransferase-to-platelet ratio, FIB-4 index, and platelet-to-Spleen ratio), along with platelet count, Spleen Size, and LS. Diagnostic and prognostic abilities were assessed by the area under the receiver operating characteristic curve (AUC) and multivariate logistic regression. LSPS correlated significantly with EV grade (P < 0.001) and was superior to the other noninvasive indices for determination of EV and high risk EV. Furthermore, LSPS was independently associated with the presence of EV (P < 0.001) and elevated EV risk (P = 0.013) by multivariate logistic regression analysis. The optimal cutoff values of LSPS for EV and high risk EV were 1.1 and 2.2, respectively, at which AUC, negative predictive value, and accuracy were 0.821 [95 % confidence interval (CI) 0.743–0.899], 91.9, and 84.3 % and 0.859 (95 % CI 0.736–0.981), 95.5, and 76.9 %, respectively. LSPS represents a useful, noninvasive, accurate method to detect EV and a high EV risk in Japanese patients with CLD.
Roger L Vallejo - One of the best experts on this subject based on the ideXlab platform.
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identification of single nucleotide polymorphism markers associated with bacterial cold water disease resistance and Spleen Size in rainbow trout
Frontiers in Genetics, 2015Co-Authors: Sixin Liu, Roger L Vallejo, Yniv Palti, David P Marancik, Guangtu Gao, Alvaro G Hernandez, Gregory D WiensAbstract:Bacterial cold water disease (BCWD) is one of the frequent causes of elevated mortality in salmonid aquaculture. Previously, we identified and validated microsatellites on chromosome Omy19 associated with QTL (quantitative trait loci) for BCWD resistance and Spleen Size in rainbow trout. Recently, SNPs (single nucleotide polymorphism) have become the markers of choice for genetic analyses in rainbow trout as they are highly abundant, cost-effective and are amenable for high throughput genotyping. The objective of this study was to identify SNP markers associated with BCWD resistance and Spleen Size using both genome-wide association studies (GWAS) and linkage-based QTL mapping approaches. A total of 298 offspring from the two half-sib families used in our previous study to validate the significant BCWD QTL on chromosome Omy19 were genotyped with RAD-seq (restriction-site-associated DNA sequencing), and 7,849 informative SNPs were identified. Based on GWAS, 18 SNPs associated with BCWD resistance and 20 SNPs associated with Spleen Size were identified. Linkage-based QTL mapping revealed three significant QTL for BCWD resistance. In addition to the previously validated dam-derived QTL on chromosome Omy19, two significant BCWD QTL derived from the sires were identified on chromosomes Omy8 and Omy25, respectively. A sire-derived significant QTL for Spleen Size on chromosome Omy2 was detected. The SNP markers reported in this study will facilitate fine mapping to identify positional candidate genes for BCWD resistance in rainbow trout.
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validation of linked qtl for bacterial cold water disease resistance and Spleen Size on rainbow trout chromosome omy19
Aquaculture, 2014Co-Authors: Roger L Vallejo, Yniv Palti, David P Marancik, Gregory D WiensAbstract:Abstract Bacterial cold water disease (BCWD) is caused by infection with Flavobacterium psychrophilum , and outbreaks cause significant economic losses in salmonid aquaculture. Previously, we identified a major QTL for BCWD resistance on rainbow trout chromosome Omy19 as well as a QTL for Spleen Size (SPLW = Spleen weight and SPLI = Spleen index) which in naive fish is a surrogate indicator of BCWD resistance. The objective of this study was to validate the BCWD resistance and Spleen Size QTL in a subsequent generation and investigate whether the correlation between BCWD resistance and Spleen Size loci on Omy19 was due to close linkage or pleiotropy. We designed four full-sib matings whose offspring were evaluated for BCWD resistance, body weight, SPLW and SPLI. A total of 800 offspring were genotyped with seven microsatellite markers from Omy19. Our analyses confirmed the presence of QTL for BCWD and Spleen Size on Omy19. Our findings also suggest that BCWD resistance and Spleen Size are not influenced by a single pleiotropic QTL on Omy19 as the QTL were separately inherited in the families studied. These data increase our understanding of the genetic basis of rainbow trout BCWD resistance.
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assessment of genetic correlation between bacterial cold water disease resistance and Spleen index in a domesticated population of rainbow trout identification of qtl on chromosome omy19
PLOS ONE, 2013Co-Authors: Gregory D Wiens, Roger L Vallejo, Timothy D Leeds, Yniv Palti, Sima Hadidi, Jason P Evenhuis, Timothy J Welch, Caird E RexroadAbstract:Selective breeding of animals for increased disease resistance is an effective strategy to reduce mortality in aquaculture. However, implementation of selective breeding programs is limited by an incomplete understanding of host resistance traits. We previously reported results of a rainbow trout selection program that demonstrated increased survival following challenge with Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD). Mechanistic study of disease resistance identified a positive phenotypic correlation between post-challenge survival and Spleen somatic-index (SI). Herein, we investigated the hypothesis of a genetic correlation between the two traits influenced by colocalizing QTL. We evaluated the inheritance and calculated the genetic correlation in five year-classes of odd- and even-year breeding lines. A total of 322 pedigreed families (n = 25,369 fish) were measured for disease resistance, and 251 families (n = 5,645 fish) were evaluated for SI. Spleen index was moderately heritable in both even-year (h(2) = 0.56±0.18) and odd-year (h(2) = 0.60±0.15) lines. A significant genetic correlation between SI and BCWD resistance was observed in the even-year line (rg = 0.45±0.20, P = 0.03) but not in the odd-year line (rg = 0.16±0.12, P = 0.19). Complex segregation analyses of the even-year line provided evidence of genes with major effect on SI, and a genome scan of a single family, 2008132, detected three significant QTL on chromosomes Omy19, 16 and 5, in addition to ten suggestive QTL. A separate chromosome scan for disease resistance in family 2008132 identified a significant BCWD QTL on Omy19 that was associated with time to death and percent survival. In family 2008132, Omy19 microsatellite alleles that associated with higher disease resistance also associated with increased Spleen Size raising the hypothesis that closely linked QTL contribute to the correlation between these traits. To our knowledge, this is the first estimation of Spleen Size heritability and evidence for genetic linkage with specific disease resistance in a teleost fish.
Jack Kutti - One of the best experts on this subject based on the ideXlab platform.
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Measurement of Spleen Size using gamma camera scintigraphy in essential thrombocythaemia
European journal of haematology, 2009Co-Authors: Peter Revesz, Jan Carneskog, Hans Wadenvik, Lennart Jarneborn, Jack KuttiAbstract:: By using gamma camera imaging the Spleen Size was determined in 33 consecutive patients with essential thrombocythaemia (ET) and in 33 consecutive patients with reactive thrombocytosis (RT). All ET patients were newly diagnosed and had not received myelosuppressive treatment prior to study; they all fulfilled the criteria for ET as established by the Polycythemia Vera Study Group. In both posterior and lateral projections, the Spleen area in the group of ET patients was significantly larger than in the RT patients. The present study has shown that 39% of ET patients at diagnosis have splenic enlargement. Evaluation of Spleen Size is therefore a useful diagnostic test in patients presenting with unexplained thrombocytosis.
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the relationship between splenic platelet pool and Spleen Size
Scandinavian Journal of Haematology, 2009Co-Authors: Jack Kutti, Aleksander Weinfeld, Jan WestinAbstract:The relationship between the exchangeable splenic platelet pool, determined by recovery of infused 51Cr-labelled platelets, and the Spleen Size, determined by 99mTc scintigraphy, has been investigated in 22 cases of polycythaemia vera and 6 control subjects. The results have shown a highly significant negative correlation, indicating that with increasing splenomegaly a larger proportion of the body platelet mass is pooled in the Spleen. A scintigraphic determination of the Spleen Size gives a rough estimation of the splenic platelet pool.
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assessment of Spleen Size using gamma camera scintigraphy in newly diagnosed patients with essential thrombocythaemia and polycythaemia vera
European Journal of Haematology, 2009Co-Authors: Jan Carneskog, Hans Wadenvik, Martha Fjalling, Jack KuttiAbstract:By using gamma camera imaging the Spleen Size was assessed in 18 consecutive patients with essential thrombocythaemia (ET) and in 18 consecutive patients with polycythaemia vera (PV). All ET and PV patients were newly diagnosed and had not received any myelosuppressive therapy prior to study. The Spleen areas in both posterior and left lateral projections were determined. Eighteen consecutive patients with idiopathic thrombocytopenic purpura (ITP) served as a control group since by definition they do not present with splenic enlargement; in these latter subjects the mean posterior and left lateral splenic areas were almost identical (48 +/- 15 and 47 +/- 17 cm2, respectively). In comparison with this control group patients with ET and PC had significantly larger Spleens. In both ET and in PV patients the left lateral Spleen scan area exceeded the posterior one. Patients with PV had larger splenic areas in both projections than did patients with ET, but the differences were not statistically significant. Compared to the ITP patients it was found that at least 50% of the ET patients and at least 61% of the PV patients at diagnosis presented with splenomegaly.
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platelet production and platelet survival in polycythaemia vera with special reference to the Spleen Size
Scandinavian Journal of Haematology, 2009Co-Authors: Jack Kutti, Aleksander WeinfeldAbstract:Studies of platelet survival and of platelet production rate were performed in 20 patients with active polycythaemia vera (PV). 8 of them were classified as non-splenomegalic and 12 had splenomegaly. The results were compared with a control material consisting of 16 haematologically normal subjects of similar age. Platelet recovery was significantly lower in splenomegalic as compared with non-splenomegalic PV patients. Platelet recovery in the latter group was, however, also significantly lower than in control subjects. Platelet mean life span and platelet half-life time were obtained by fitting the experimental data to an arbitrary mathematical function by using a digital computer. The results indicate that platelet survival is shorter in PV patients with splenomegaly as compared with PV patients wihout splenomegaly. Irrespective of the peripheral platelet count the platelet production rate in all PV patients exceeded the upper range for the control subjects. The mean platelet production rate was approximately 9 times normal in the splenomegalic group, and 5 times normal in the group without splenomegaly. There was a large individual variation for the platelet production rate, and the dispersion of values was more pronounced in the splenomegalic group.
Yniv Palti - One of the best experts on this subject based on the ideXlab platform.
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identification of single nucleotide polymorphism markers associated with bacterial cold water disease resistance and Spleen Size in rainbow trout
Frontiers in Genetics, 2015Co-Authors: Sixin Liu, Roger L Vallejo, Yniv Palti, David P Marancik, Guangtu Gao, Alvaro G Hernandez, Gregory D WiensAbstract:Bacterial cold water disease (BCWD) is one of the frequent causes of elevated mortality in salmonid aquaculture. Previously, we identified and validated microsatellites on chromosome Omy19 associated with QTL (quantitative trait loci) for BCWD resistance and Spleen Size in rainbow trout. Recently, SNPs (single nucleotide polymorphism) have become the markers of choice for genetic analyses in rainbow trout as they are highly abundant, cost-effective and are amenable for high throughput genotyping. The objective of this study was to identify SNP markers associated with BCWD resistance and Spleen Size using both genome-wide association studies (GWAS) and linkage-based QTL mapping approaches. A total of 298 offspring from the two half-sib families used in our previous study to validate the significant BCWD QTL on chromosome Omy19 were genotyped with RAD-seq (restriction-site-associated DNA sequencing), and 7,849 informative SNPs were identified. Based on GWAS, 18 SNPs associated with BCWD resistance and 20 SNPs associated with Spleen Size were identified. Linkage-based QTL mapping revealed three significant QTL for BCWD resistance. In addition to the previously validated dam-derived QTL on chromosome Omy19, two significant BCWD QTL derived from the sires were identified on chromosomes Omy8 and Omy25, respectively. A sire-derived significant QTL for Spleen Size on chromosome Omy2 was detected. The SNP markers reported in this study will facilitate fine mapping to identify positional candidate genes for BCWD resistance in rainbow trout.
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validation of linked qtl for bacterial cold water disease resistance and Spleen Size on rainbow trout chromosome omy19
Aquaculture, 2014Co-Authors: Roger L Vallejo, Yniv Palti, David P Marancik, Gregory D WiensAbstract:Abstract Bacterial cold water disease (BCWD) is caused by infection with Flavobacterium psychrophilum , and outbreaks cause significant economic losses in salmonid aquaculture. Previously, we identified a major QTL for BCWD resistance on rainbow trout chromosome Omy19 as well as a QTL for Spleen Size (SPLW = Spleen weight and SPLI = Spleen index) which in naive fish is a surrogate indicator of BCWD resistance. The objective of this study was to validate the BCWD resistance and Spleen Size QTL in a subsequent generation and investigate whether the correlation between BCWD resistance and Spleen Size loci on Omy19 was due to close linkage or pleiotropy. We designed four full-sib matings whose offspring were evaluated for BCWD resistance, body weight, SPLW and SPLI. A total of 800 offspring were genotyped with seven microsatellite markers from Omy19. Our analyses confirmed the presence of QTL for BCWD and Spleen Size on Omy19. Our findings also suggest that BCWD resistance and Spleen Size are not influenced by a single pleiotropic QTL on Omy19 as the QTL were separately inherited in the families studied. These data increase our understanding of the genetic basis of rainbow trout BCWD resistance.
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assessment of genetic correlation between bacterial cold water disease resistance and Spleen index in a domesticated population of rainbow trout identification of qtl on chromosome omy19
PLOS ONE, 2013Co-Authors: Gregory D Wiens, Roger L Vallejo, Timothy D Leeds, Yniv Palti, Sima Hadidi, Jason P Evenhuis, Timothy J Welch, Caird E RexroadAbstract:Selective breeding of animals for increased disease resistance is an effective strategy to reduce mortality in aquaculture. However, implementation of selective breeding programs is limited by an incomplete understanding of host resistance traits. We previously reported results of a rainbow trout selection program that demonstrated increased survival following challenge with Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD). Mechanistic study of disease resistance identified a positive phenotypic correlation between post-challenge survival and Spleen somatic-index (SI). Herein, we investigated the hypothesis of a genetic correlation between the two traits influenced by colocalizing QTL. We evaluated the inheritance and calculated the genetic correlation in five year-classes of odd- and even-year breeding lines. A total of 322 pedigreed families (n = 25,369 fish) were measured for disease resistance, and 251 families (n = 5,645 fish) were evaluated for SI. Spleen index was moderately heritable in both even-year (h(2) = 0.56±0.18) and odd-year (h(2) = 0.60±0.15) lines. A significant genetic correlation between SI and BCWD resistance was observed in the even-year line (rg = 0.45±0.20, P = 0.03) but not in the odd-year line (rg = 0.16±0.12, P = 0.19). Complex segregation analyses of the even-year line provided evidence of genes with major effect on SI, and a genome scan of a single family, 2008132, detected three significant QTL on chromosomes Omy19, 16 and 5, in addition to ten suggestive QTL. A separate chromosome scan for disease resistance in family 2008132 identified a significant BCWD QTL on Omy19 that was associated with time to death and percent survival. In family 2008132, Omy19 microsatellite alleles that associated with higher disease resistance also associated with increased Spleen Size raising the hypothesis that closely linked QTL contribute to the correlation between these traits. To our knowledge, this is the first estimation of Spleen Size heritability and evidence for genetic linkage with specific disease resistance in a teleost fish.