• 1.

    Hammer TA, Venta PJ, Eyster GE. The genetic basis of dilated cardiomyopathy in Doberman pinschers. Anim Genet 1996;27:101119.

  • 2.

    Calvert CA. Dilated congestive cardiomyopathy in Doberman pinschers. Compend Contin Educ Pract Vet 1986;8:417430.

  • 3.

    Meurs KM, Fox PR, Norgard M, et al. A prospective genetic evaluation of familial dilated cardiomyopathy in the Doberman pinscher. J Vet Intern Med 2007;21:10161020.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Buchanan JW. Prevalence of cardiovascular disorders. In: Fox PR, Sisson DD, Moise NS, eds. Textbook of canine and feline cardiology. 2nd ed. Philadelphia: WB Saunders Co, 1999;457470.

    • Search Google Scholar
    • Export Citation
  • 5.

    Tidholm A, Jönsson L. A retrospective study of canine dilated cardiomyopathy (189 cases). J Am Anim Hosp Assoc 1997;33:544550.

  • 6.

    Monnet E, Orton EC, Salman M, et al. Idiopathic dilated cardiomyopathy in dogs: survival and prognostic indicators. J Vet Intern Med 1995;9:27.

    • Search Google Scholar
    • Export Citation
  • 7.

    Burkett EL, Hershberger RE. Clinical and genetic issues in familial dilated cardiomyopathy. J Am Coll Cardiol 2005;45:969981.

  • 8.

    Fatkin D, Graham RM. Molecular mechanisms of inherited cardiomyopathies. Physiol Rev 2002;82:945980.

  • 9.

    Osterziel KJ, Hassfeld S, Geier C, et al. Familial dilated cardiomyopathy [in German]. Herz 2005;30:529534.

  • 10.

    Olson TM, Michels VV, Thibodeau SN, et al. Actin mutations in dilated cardiomyopathy, a heritable form of heart failure. Science 1998;280:750752.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Towbin JA. The role of cytoskeletal proteins in cardiomyopathies. Curr Opin Cell Biol 1998;10:131139.

  • 12.

    Towbin JA, Hejtmancik F, Brink P, et al. X-linked dilated cardiomyopathy. Molecular genetic evidence of linkage to the Duchenne muscular dystrophy (dystrophin) gene at the Xp21 locus. Circulation 1993;87:18541865.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13.

    Maeda M, Holder E, Lowes B, et al. Dilated cardiomyopathy associated with deficiency of the cytoskeletal protein metavinculin. Circulation 1997;95:1720.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Stabej P, Imholz S, Versteeg SA, et al. Characterization of the canine desmin gene (DES) and evaluation as a candidate gene for dilated cardiomyopathy in the Dobermann. Gene 2004;340:241249.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15.

    Stabej P, Leegwater PA, Imholz S, et al. The canine sarcoglycan delta gene: BAC clone contig assembly, chromosome assignment and interrogation as a candidate gene for dilated cardiomyopathy in Dobermann dogs. Cytogenet Genome Res 2005;111:140146.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Stabej P, Leegwater PA, Stokhof AA, et al. Evaluation of the phospholamban gene in purebred large-breed dogs with dilated cardiomyopathy. Am J Vet Res 2005;66:432436.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17.

    Meurs KM, Magnon AL, Spier AW, et al. Evaluation of the cardiac actin gene in Doberman Pinschers with dilated cardiomyopathy. Am J Vet Res 2001;62:3336.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Meurs KM, Spier AW, Wright NA, et al. Use of ambulatory electrocardiography for detection of ventricular premature complexes in healthy dogs. J Am Vet Med Assoc 2001;218:12911292.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19.

    Thomas WP, Gaber CE, Jacobs GJ, et al. Recommendations for standards in transthoracic two-dimensional echocardiography in the dog and cat. J Vet Intern Med 1993;7:247252.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 20.

    O'Grady MR, Horne R. Occult dilated cardiomyopathy in the Doberman pinscher, in Proceedings. 13th Annu Meet Am Coll Vet Intern Med 1995;298299.

    • Search Google Scholar
    • Export Citation
  • 21.

    Meurs KM, Kittleson MD, Spangler E, et al. Nine polymorphisms within the head and hinge region of the feline cardiac beta-myosin heavy chain gene. Anim Genet 2000;31:231.

    • Search Google Scholar
    • Export Citation
  • 22.

    Rozen S, Skaletsky HJ. Primer 3 on the WWW for general users and for biologist programmers. In: Krawetz SA, Misener S, eds. Bioinformatics methods and protocols: methods in molecular biology. Totowa, NJ: Human Press, 2000;365386.

    • Search Google Scholar
    • Export Citation
  • 23.

    e!Ensembl. Available at: www.ensembl.org/index.html. Accessed Dec 1, 2007.

  • 24.

    Lindblad-Toh K, Wade CM, Mikkelsen TS, et al. Genome sequence, comparative analysis and haplotype structure of the domestic dog. Nature 2005;438:803819.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 25.

    Rankin J, Ellard S. The laminopathies: a clinical review. Clin Genet 2006;70:261274.

  • 26.

    Daehmlow S, Erdmann J, Knueppel T, et al. Novel mutations in sarcomeric protein genes in dilated cardiomyopathy. Biochem Biophys Res Commun 2002;298:116120.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 27.

    Kamisago M, Sharma SD, DePlama SR, et al. Mutations in sarcomere protein genes as a cause of dilated cardiomyopathy. N Engl J Med 2000;343:16881696.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 28.

    Li D, Czernuszewicz GZ, Gonzalez O, et al. Novel cardiac troponin T mutation as a cause of familial dilated cardiomyopathy. Circulation 2001;104:21882193.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29.

    Mogensen J, Murphy RT, Shaw T, et al. Severe disease expression of cardiac troponin C and T mutations in patients with idiopathic dilated cardiomyopathy. J Am Coll Cardiol 2004;44:20332040.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 30.

    Knöll R, Hoshijima M, Hoffman HM, et al. The cardiac mechanical stretch sensor machinery involves a Z disc complex that is defective in a subset of human dilated cardiomyopathy. Cell 2002;111:943955.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 31.

    Walker J. New Doberman Pinscher. Hoboken, NJ: Howell Book House, 1981;1825.

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Molecular evaluation of five cardiac genes in Doberman Pinschers with dilated cardiomyopathy

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  • 1 Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164.
  • | 2 Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164.
  • | 3 Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164.

Abstract

Objective—To sequence the exonic and splice site regions of 5 cardiac genes associated with the human form of familial dilated cardiomyopathy (DCM) in Doberman Pinschers with DCM and to identify a causative mutation.

Animals—5 unrelated Doberman Pinschers with DCM and 2 unaffected Labrador Retrievers (control dogs).

Procedures—Exonic and splice site regions of the 5 genes encoding the cardiac proteins troponin C, lamin A/C, cysteine- and glycine-rich protein 3, cardiac troponin T, and the β-myosin heavy chain were sequenced. Sequences were compared for nucleotide changes between affected dogs and the published canine sequences and 2 control dogs. Base pair changes were considered to be causative for DCM if they were present in an affected dog but not in the control dogs or published sequences and if they involved a conserved amino acid and changed that amino acid to a different polarity, acid-base status, or structure.

Results—A causative mutation for DCM in Doberman Pinschers was not identified, although single nucleotide polymorphisms were detected in some dogs in the cysteine- and glycine-rich protein 3, β-myosin heavy chain, and troponin T genes.

Conclusions and Clinical Relevance—Mutations in 5 of the cardiac genes associated with the development of DCM in humans did not appear to be causative for DCM in Doberman Pinschers. Continued evaluation of additional candidate genes or a focused approach with an association analysis is warranted to elucidate the molecular cause of this important cardiac disease in Doberman Pinschers.

Abstract

Objective—To sequence the exonic and splice site regions of 5 cardiac genes associated with the human form of familial dilated cardiomyopathy (DCM) in Doberman Pinschers with DCM and to identify a causative mutation.

Animals—5 unrelated Doberman Pinschers with DCM and 2 unaffected Labrador Retrievers (control dogs).

Procedures—Exonic and splice site regions of the 5 genes encoding the cardiac proteins troponin C, lamin A/C, cysteine- and glycine-rich protein 3, cardiac troponin T, and the β-myosin heavy chain were sequenced. Sequences were compared for nucleotide changes between affected dogs and the published canine sequences and 2 control dogs. Base pair changes were considered to be causative for DCM if they were present in an affected dog but not in the control dogs or published sequences and if they involved a conserved amino acid and changed that amino acid to a different polarity, acid-base status, or structure.

Results—A causative mutation for DCM in Doberman Pinschers was not identified, although single nucleotide polymorphisms were detected in some dogs in the cysteine- and glycine-rich protein 3, β-myosin heavy chain, and troponin T genes.

Conclusions and Clinical Relevance—Mutations in 5 of the cardiac genes associated with the development of DCM in humans did not appear to be causative for DCM in Doberman Pinschers. Continued evaluation of additional candidate genes or a focused approach with an association analysis is warranted to elucidate the molecular cause of this important cardiac disease in Doberman Pinschers.

Dilated cardiomyopathy is a familial disease in Doberman Pinschers and is inherited as an autosomal dominant trait.1–3 Onset of DCM is in adulthood, and affected dogs may have myocardial dysfunction, tachyarrhythmias, and congestive heart failure.4–6 At this time, the molecular basis for the disease in Doberman Pinschers is unknown.

A similar form of cardiomyopathy exists in humans and is inherited in at least 20% to 50% of cases.7 Familial DCM in humans has been associated with mutations in > 20 genes and is most commonly inherited in an autosomal dominant pattern similar to that of Doberman Pinschers. The most common causes of the autosomal dominant form of familial DCM are single base pair changes in the coding region of a gene that encodes for the one of the following proteins: lamin A/C, MYH7, troponin T, CSRP3, troponin C, D-sarcoglycan, desmin, actin, troponin I, actinin-A2, α-tropomyosin, and titin-cap, among others.7–13 A similarity between many of these genes is that they encode for cytoskeletal proteins with structural functions that include maintaining structural integrity, preserving cell shape, organizing the contractile apparatus, and enabling the cell to withstand mechanical stress.13 One proposed theory for the development of DCM is that an abnormality of a cytoskeletal protein may be a common factor in the development of the disease and that without the structural support provided by these proteins, dilation and dysfunction of the heart develop.11

The etiology of familial DCM in Doberman Pinschers is unknown. Previous studies14,15 have excluded some of the genes responsible for the disease in humans, including the desmin and D-sarcoglycan genes, by the typing of adjacent genetic markers in affected and unaffected Doberman Pinschers. Additional studies16,17 have excluded the promoter and coding regions of the phospholamban gene and coding region of the actin gene via direct sequencing in affected and unaffected dogs. Exclusion of these 4 genes still leaves several other genes associated with the autosomal dominant form of the human disease yet to be evaluated. Additionally, it is possible that Doberman Pinscher DCM does not have the same genetic cause as in humans and that a mutation will be identified in a novel gene. A linkage analysis approach was performed to attempt to identify a statistical relationship between the disease and a specific genetic region to focus the evaluation of additional cardiac genes.6 Linkage analysis was not able to identify a significant region of interest, but the strongest, yet not significantly, associated marker was found on canine chromosome 20.6

The objectives of the study reported here were to evaluate the splice site and coding regions of 5 additional cardiac genes in Doberman Pinschers with DCM. The genes evaluated were the 4 most commonly reported as causative in humans, including lamin A/C, MYH7, troponin T, and CSRP3. A fifth gene, troponin C, was selected for evaluation because of its location on canine chromosome 20, the chromosome with the highest linkage score in a previous linkage study.6

Materials and Methods

This study was conducted under the guidelines of the Animal Care and Use Committee of The Ohio State University. Written consent authorizing study participation was obtained from each client.

Phenotypic classification and pedigree analysis—Five unrelated Doberman Pinschers with a diagnosis of DCM as determined via physical examination, 24-hour AECG, and an echocardiogram (2 dimensional and M-mode) and 2 unrelated Labrador Retrievers (control dogs) were evaluated. The AECG was recorded with a 3-channel transthoracic systema by use of a previously described technique.18 The number of VPCs was tabulated. Echocardiographic examination was performed via transthoracic echocardiography and included 2-dimensional and M-mode evaluation.b Left ventricular internal diameter during systole, LVIDD, and FS(%) were determined from the M-mode study at the left ventricular level. The examinations were conducted without sedation via standard clinical techniques described for dogs.19 Participating dogs were classified as affected on the basis of echocardiographic measurements of an LVIDD > 4.6 cm or LVIDS > 3.8 cm with an FS < 25%.20

Genotyping—Genomic DNA samples were prepared from blood samples, as described.21 Briefly, cells were osmotically lysed in 2X sucrose-Triton and Tris-NH4Cl buffer, and nuclei were pelleted by centrifugation at 800 × g for 20 minutes at 4°C. Pellets were resuspended in saline (0.9% NaCl) solution–EDTA with 1% SDS and 50 μg of proteinase K/mL and incubated overnight at 56°C. The samples were subjected to 2 successive phenol:chloroform:isoamyl (25:24:1; pH, 8) extractions and 1 chloroform extraction. The DNA was ethanol precipitated, washed with 75% ethanol, and resuspended in 250 μL of Tris EDTA buffer (10mM Tris-HCl and 1mM EDTA; pH, 8).

Polymerase chain reaction amplification primers were designed for all exons of lamin A/C, MYH7, troponin T, troponin C, and CSRP3 genes by use of computer software and the canine nucleotide sequence information22 (ENSCAFG00000009404, ENSCAFG00000010798, ENSCAFG00000009424, ENSCAFG00000016863, and ENSCAFG0000001161923).

Standard PCR amplifications were carried out via NH4SO4 amplification buffer, 0.1 U of Taq DNA polymerasec/μL of reaction volume, 2.5mM MgCl2, 12.5μM of each dNTP, 2.5mM of each PCR amplification primer, and 100 ng of template DNA. Samples were denatured for 5 minutes at 94°C, followed by 40 cycles of 94°C for 20 seconds, 58°C for 30 seconds, 72°C for 30 seconds, and 72°C for 7 minutes. The annealing temperature was optimized to accommodate the respective primer requirement.

Residual amplification primers and dNTPs were removed from the PCR product. Amplicons were then subjected to nucleotide sequence determination and analyzed on a sequencerd by use of a forward and reverse primer for each reaction for every sample.

The sequences were compared for nucleotide sequence changes between affected dogs and the published normal canine sequence or the control dogs.24 Base pair changes were considered to be possibly causative for DCM when they were present in any of the affected dogs. When a base pair alteration was detected in any of the affected dogs, the alteration was evaluated to determine whether it changed a conserved amino acid and whether that amino acid was changed to one of a different polarity, acid-base status, or structure because these could be evidence for a causative change.7

Results

The Doberman Pinscher group consisted of 3 females and 2 males (age range, 6 to 10 years; mean, 9 years). Affected dogs had a median FS of 12% (range, 9% to 17%), median LVIDD of 5.4 cm (range, 5.0 to 8.0), median LVIDS of 4.6 cm (range, 4.2 to 7.1), and median number of VPCs/24 h of 250 (range, 77 to 15,419/24 h) The Labrador Retriever group (control group) consisted of 2 unrelated dogs (a 4-year-old male and a 7-year-old female).

No base pair differences that met the criteria for a causative change were identified in the exonic or splice site regions of the lamin A/C, MYH7, troponin T, troponin C, or CSRP3 genes between the affected Doberman Pinschers and the control dogs or the published canine sequence. A single nucleotide polymorphism that did not segregate with disease was evident in the CSRP3, MYH7, and troponin T genes (Table 1).

Table 1—

Single nucleotide polymorphisms detected in the canine CSRP3, MYH7, and troponin T genes in a group of 5 Doberman Pinschers with DCM and 2 unaffected Labrador Retrievers.

GeneExonCodonAmino acidDog groupDogs
CSRP349ThreonineAffected, controls1 Female control
1 Female affected
1 Male affected
Troponin T715AlanineAffected1 Female affected
1 Male affected
MYH73154LysineAffected, controls1 Male control
2 Male affected
2 Female affected

Discussion

In the study reported here, a causative mutation was not identified in the coding regions of the 5 cardiac genes evaluated. The criterion for a causative mutation was defined as a single base pair change that segregated with affected dogs, occurred in a highly conserved region, and changed an amino acid.7 Although a few base pair changes were detected, none of them changed an amino acid or consistently segregated with disease. The genes evaluated in this study have not been completely excluded, however, because it is still possible that a causative error may exist in the promoter or noncoding regions of the gene. We believe this to be unlikely given that the reported mutations associated with the human disease are all single base pair changes or small deletions that exist in the coding regions of the genes.7–13

The gene sequences from the affected Doberman Pinschers were compared with the published canine sequence (derived from a Boxer) as well as 2 adult Labrador Retrievers. Because the published canine sequence is from a Boxer, a breed known to develop DCM, DNA from 2 Labrador Retrievers was also compared as a control because this breed has a low prevalence of DCM.4 Additional Doberman Pinschers were not used as controls because we did not want to risk the accidental inclusion of any affected dogs that had not yet developed this adult-onset phenotype as control dogs.

The 5 genes evaluated for this study were selected predominantly on the basis of their importance in the development of autosomal dominant DCM in humans. The lamin A/C gene is one of the most common genes reported as containing a mutation causative for DCM in humans.7 The lamin A/C gene encodes for lamin A and lamin C, which are nuclear envelope proteins that appear to have structural and regulatory functions.25 The genes that encode for the sarcomeric proteins MYH7, troponin T, and troponin C were evaluated, although mutations in the genes that encode for sarcomeric proteins are more commonly associated with development of hypertrophic cardiomyopathy. More recently, however, point mutations in the these genes have also been associated with development of autosomal dominant DCM.26–29 We also had increased interest in the evaluation of the troponin C gene because it is located on canine chromosome 20 (36,113,191–36,114,151 bp). We have identified a positive, but not significant, linkage score on chromosome 20 in the 29,594,835–29,595,016 bp region via linkage analysis, so we considered troponin C to be of increased interest as a candidate for the disease.6 In addition, the gene for CSRP3 was evaluated. Cysteine- and glycine-rich protein 3 is an LIM domain protein that appears to be important in the stabilization of the titin/Z disc complex, which is part of the myocyte cytoskeleton.30

One limitation of this study was the small number of dogs in the affected group. It is possible that a mutation may be identified in one of these genes in some Doberman Pinschers with DCM, although it was not identified in the dogs evaluated here. However, this would seem unlikely. Doberman Pinschers are purebred dogs with a closed gene pool. It has been estimated that by the 1950s, 50% of the registered Doberman Pinschers in the United States were descendents from a single family of dogs.31 Therefore, it is reasonable to assume that most of the affected dogs in this breed will share a common mutation because of the founder effect. Although a causative mutation was not identified in this study, the clinical importance of this disease as well as its strong familial nature warrants continued evaluation of additional candidate genes or an association analysis.

ABBREVIATIONS

AECG

Ambulatory electrocardiogram

CSRP3

Cysteine- and glycine-rich protein 3

DCM

Dilated cardiomyopathy

FS

Fractional shortening

LVIDD

Left ventricular internal diameter during diastole

LVIDS

Left ventricular internal diameter during systole

MYH7

β-myosin heavy chain

VPC

Ventricular premature complex

a.

Delmar Medical Systems, Irvine, Calif.

b.

GE Healthcare BioSciences Corp, Piscataway, NJ.

c.

Fermentas, Hanover, Md.

d.

Applied Biosystems, Foster City, Calif.

References

  • 1.

    Hammer TA, Venta PJ, Eyster GE. The genetic basis of dilated cardiomyopathy in Doberman pinschers. Anim Genet 1996;27:101119.

  • 2.

    Calvert CA. Dilated congestive cardiomyopathy in Doberman pinschers. Compend Contin Educ Pract Vet 1986;8:417430.

  • 3.

    Meurs KM, Fox PR, Norgard M, et al. A prospective genetic evaluation of familial dilated cardiomyopathy in the Doberman pinscher. J Vet Intern Med 2007;21:10161020.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 4.

    Buchanan JW. Prevalence of cardiovascular disorders. In: Fox PR, Sisson DD, Moise NS, eds. Textbook of canine and feline cardiology. 2nd ed. Philadelphia: WB Saunders Co, 1999;457470.

    • Search Google Scholar
    • Export Citation
  • 5.

    Tidholm A, Jönsson L. A retrospective study of canine dilated cardiomyopathy (189 cases). J Am Anim Hosp Assoc 1997;33:544550.

  • 6.

    Monnet E, Orton EC, Salman M, et al. Idiopathic dilated cardiomyopathy in dogs: survival and prognostic indicators. J Vet Intern Med 1995;9:27.

    • Search Google Scholar
    • Export Citation
  • 7.

    Burkett EL, Hershberger RE. Clinical and genetic issues in familial dilated cardiomyopathy. J Am Coll Cardiol 2005;45:969981.

  • 8.

    Fatkin D, Graham RM. Molecular mechanisms of inherited cardiomyopathies. Physiol Rev 2002;82:945980.

  • 9.

    Osterziel KJ, Hassfeld S, Geier C, et al. Familial dilated cardiomyopathy [in German]. Herz 2005;30:529534.

  • 10.

    Olson TM, Michels VV, Thibodeau SN, et al. Actin mutations in dilated cardiomyopathy, a heritable form of heart failure. Science 1998;280:750752.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 11.

    Towbin JA. The role of cytoskeletal proteins in cardiomyopathies. Curr Opin Cell Biol 1998;10:131139.

  • 12.

    Towbin JA, Hejtmancik F, Brink P, et al. X-linked dilated cardiomyopathy. Molecular genetic evidence of linkage to the Duchenne muscular dystrophy (dystrophin) gene at the Xp21 locus. Circulation 1993;87:18541865.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13.

    Maeda M, Holder E, Lowes B, et al. Dilated cardiomyopathy associated with deficiency of the cytoskeletal protein metavinculin. Circulation 1997;95:1720.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 14.

    Stabej P, Imholz S, Versteeg SA, et al. Characterization of the canine desmin gene (DES) and evaluation as a candidate gene for dilated cardiomyopathy in the Dobermann. Gene 2004;340:241249.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15.

    Stabej P, Leegwater PA, Imholz S, et al. The canine sarcoglycan delta gene: BAC clone contig assembly, chromosome assignment and interrogation as a candidate gene for dilated cardiomyopathy in Dobermann dogs. Cytogenet Genome Res 2005;111:140146.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16.

    Stabej P, Leegwater PA, Stokhof AA, et al. Evaluation of the phospholamban gene in purebred large-breed dogs with dilated cardiomyopathy. Am J Vet Res 2005;66:432436.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17.

    Meurs KM, Magnon AL, Spier AW, et al. Evaluation of the cardiac actin gene in Doberman Pinschers with dilated cardiomyopathy. Am J Vet Res 2001;62:3336.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18.

    Meurs KM, Spier AW, Wright NA, et al. Use of ambulatory electrocardiography for detection of ventricular premature complexes in healthy dogs. J Am Vet Med Assoc 2001;218:12911292.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19.

    Thomas WP, Gaber CE, Jacobs GJ, et al. Recommendations for standards in transthoracic two-dimensional echocardiography in the dog and cat. J Vet Intern Med 1993;7:247252.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 20.

    O'Grady MR, Horne R. Occult dilated cardiomyopathy in the Doberman pinscher, in Proceedings. 13th Annu Meet Am Coll Vet Intern Med 1995;298299.

    • Search Google Scholar
    • Export Citation
  • 21.

    Meurs KM, Kittleson MD, Spangler E, et al. Nine polymorphisms within the head and hinge region of the feline cardiac beta-myosin heavy chain gene. Anim Genet 2000;31:231.

    • Search Google Scholar
    • Export Citation
  • 22.

    Rozen S, Skaletsky HJ. Primer 3 on the WWW for general users and for biologist programmers. In: Krawetz SA, Misener S, eds. Bioinformatics methods and protocols: methods in molecular biology. Totowa, NJ: Human Press, 2000;365386.

    • Search Google Scholar
    • Export Citation
  • 23.

    e!Ensembl. Available at: www.ensembl.org/index.html. Accessed Dec 1, 2007.

  • 24.

    Lindblad-Toh K, Wade CM, Mikkelsen TS, et al. Genome sequence, comparative analysis and haplotype structure of the domestic dog. Nature 2005;438:803819.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 25.

    Rankin J, Ellard S. The laminopathies: a clinical review. Clin Genet 2006;70:261274.

  • 26.

    Daehmlow S, Erdmann J, Knueppel T, et al. Novel mutations in sarcomeric protein genes in dilated cardiomyopathy. Biochem Biophys Res Commun 2002;298:116120.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 27.

    Kamisago M, Sharma SD, DePlama SR, et al. Mutations in sarcomere protein genes as a cause of dilated cardiomyopathy. N Engl J Med 2000;343:16881696.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 28.

    Li D, Czernuszewicz GZ, Gonzalez O, et al. Novel cardiac troponin T mutation as a cause of familial dilated cardiomyopathy. Circulation 2001;104:21882193.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29.

    Mogensen J, Murphy RT, Shaw T, et al. Severe disease expression of cardiac troponin C and T mutations in patients with idiopathic dilated cardiomyopathy. J Am Coll Cardiol 2004;44:20332040.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 30.

    Knöll R, Hoshijima M, Hoffman HM, et al. The cardiac mechanical stretch sensor machinery involves a Z disc complex that is defective in a subset of human dilated cardiomyopathy. Cell 2002;111:943955.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 31.

    Walker J. New Doberman Pinscher. Hoboken, NJ: Howell Book House, 1981;1825.

Contributor Notes

Address correspondence to Dr. Meurs.