DNA sequence and haplotype variation in two candidate genes for dilated cardiomyopathy in the turkey Meleagris gallopavo Kuan-chin Lin, Jun Xu, Davida Kamara, Tuoyu Geng, Kwaku Gyenai, Kent M. Reed, and Edward J. Smith Abstract: Determining variation in genes is fundamental to understanding their function in the disease state. Cardiac tro- ponin T (cTnT) and phospholamban (PLN) genes have been implicated in dilated cardiomyopathy (DCM) in human and model species. To investigate the role of these 2 candidate genes in DCM in the turkey Meleagris gallopavo, understand- ing sequence variants and map position distribution is necessary. To this end, a total of 1854 and 1771 bp of cTnT and PLN gene sequences, respectively, were scanned for single nucleotide polymorphisms (SNPs) in a randomly bred popula- tion. A total of 15 SNPs was identified in the cTnT and PLN genomic sequences. Nine haplotypes, 5 in cTnT and 4 in PLN, were identified. Observed heterozygosities (0.02–0.39) in the turkey population were low for both genes. Within each gene, 1 SNP corresponding to a restriction enzyme site was identified and used to develop a PCR–restriction frag- ment length polymorphism (RFLP) genotyping assay. The PLN gene was genetically mapped to turkey chromosome 2, equivalent to Gallus gallus chromosome 3, and cTnT mapped to a turkey microchromosome. Although limited because of the relatively small sample size of 55 birds, the data from this SNP analysis of PLN and cTnT provide a foundation from which to evaluate the function of cTnT and PLN in the turkey. Information about the distribution of the SNPs and haplo- types will facilitate future association and linkage studies. Key words: turkey, dilated cardiomyopathy, cardiac troponin T, phospholamban, single nucleotide polymorphism. Re´sume´: La connaissance de la variation au sein des ge`nes est essentielle pour la compre´hension de leur fonction dans des cas de pathologie. Les ge`nes de la troponine cardiaque (cTnT) et du phospholambane (PLN) ont e´te´ implique´s dans l’incidence de la cardiomyopathie dilate´e (DCM) chez l’humain et des espe`ces mode`les. Afin d’e´tudier le roˆle de ces deux ge`nes candidats pour la DCM chez le dindon, Meleagris gallopavo, une connaissance des variants nucle´otidiques et de leur distribution sur la carte e´tait requise. Pour y arriver, un total de 1854 et 1771 pb respectivement des se´quences des ge`- nes cTnT et PLN ae´te´ examine´ pour des polymorphismes mononucle´otidiques (« SNP ») au sein d’une population a` repro- duction ale´atoire. Un total de 15 SNP ont e´te´ identifie´s au sein des se´quences ge´nomiques de cTnT et de PLN. Neuf haplotypes, 5 chez cTnT et 4 chez PLN ont e´te´ identifie´s. Les he´te´rozygoties observe´es (0,02–0,39) au sein de la popula- tion de dindons e´taient faibles pour les deux ge`nes. Au sein de chaque ge`ne, un SNP correspondant a` un site de restriction enzymatique a e´te´ identifie´ et employe´ pour de´velopper un test de ge´notypage PCR–RFLP. Le ge`ne PLN ae´te´ situe´ sur le chromosome 2 du dindon, ce qui correspond au chromosome 3 chez le Gallus gallus, alors que le ge`ne cTnT ae´te´ situe´ sur le minichromosome du dindon. Bien que limite´s en raison de la taille modeste de l’e´chantillon (55 oiseaux), les re´sul- tats de l’analyse SNP des ge`nes PLN et cTnT fournissent une assise pour e´lucider la fonction de ces ge`nes chez le dindon. Une connaissance de la distribution des SNP et des haplotypes facilitera de futures e´tudes d’association et de liaison ge´ne´- tique. Mots-cle´s : dindon, cardiomyopathie dilate´e, troponine cardiaque T, phospholambane, polymorphisme mononucle´otidique. [Traduit par la Re´daction] Introduction Dilated cardiomyopathy (DCM), or round heart disease, remains a major concern in poultry, including the turkey Meleagris gallopavo (Zepeda and Kooyman 2002; Paxton et al. 2005). It is estimated that DCM causes 2% to 5% mortal- ity in turkeys between hatch and 4 weeks of age. In humans, approximately 5 million people are affected by DCM annu- ally, resulting in an estimated health-care cost of about $18 million (Schmitt et al. 2003). Despite this impact, however, Received 25 October 2006. Accepted 13 March 2007. Published on the NRC Research Press Web site at genome.nrc.ca on 2 June 2007. Corresponding Editor: P. Gustafson. K. Lin, J. Xu, D. Kamara, T. Geng, K. Gyenai, and E.J. Smith. 1 Department of Animal and Poultry Sciences, 2250 Litton-Reaves Hall, Virginia Tech, Blacksburg, VA 24061, USA. K.M. Reed. Department of Veterinary and Biomedical Sciences, University of Minnesota, St. Paul, MN 55108, USA. 1 Corresponding author (e-mail: esmith@vt.edu). 463 Genome 50: 463–469 (2007) doi:10.1139/G07-022 # 2007 NRC Canada