OMIA 000224-9615 : Conotruncal heart malformations in Canis lupus familiaris

Possibly relevant human trait(s) and/or gene(s) (MIM number): 217095

Mendelian trait/disorder: no

Mode of inheritance: Multifactorial

Considered a defect: yes

Key variant known: no

Species-specific description: Conotruncal defects are a type of congenital heart defect characterized by abnormal formation and union of the endocardial cushions that normally divide the atrioventricular canal during development. The severity of the defect can vary from subclinical to life threatening. Clinical signs include exercise intolerance, cyanosis, and a systolic murmur.

Edited by Meg Sleeper, VMD and Vicki N. Meyers-Wallen, VMD, PhD, Dipl. ACT

Inheritance: Conotruncal defects are inherited as a complex trait in the Keeshond, involving multiple loci and environmental influences (Werner et al., 2005).

Mapping: There is some evidence that predisposing alleles on CFA2, CFA9, and CFA15 act synergistically to cause conotruncal defects in the Keeshond (Werner et al., 2005). However, none of these three loci alone are responsible for inheritance of the condition.

Clinical features: Clinical signs include exercise intolerance with cyanosis and a systolic murmur. Radiographs may show reduced circulation in the pulmonary vessels along with right ventricular hypertrophy. Diagnosis can be obtained by echocardiogram or angiogram.

Pathology: Opposing areas of mesenchymal tissue known as the atrioventricular endocardial cushions divide the atrioventricular canal during cardiac development. Abnormal septation is caused by abnormal formation and fusion of these cushions.

Conotruncal defects include varying degrees of abnormality in the septation of the heart during development, which are divided into four grades of severity Patterson et al., 1974).

Grade 1: The defects are subclinical, and include a persistent conus septum fusion line, an aneurysm in the ventricular septum, and absence of the papillary muscle of the conus. Otherwise, the heart is normal and no murmurs are present.

Grade 2: Affected animals have a ventricular septal defect. Grade 3: Affected dogs have Tetralogy of Fallot, which is the combination of pulmonic stenosis, ventricular septal defect, overriding aorta, and right ventricular hypertrophy. Grade 4: Affected animals have a persistent truncus arteriosus, where the pulmonary artery and aorta arise from the truncus and there is no supraventricular crest.

Occasionally, affected dogs also have anomalies of the aortic arch system, such as persistent ductus arteriosus, retroesophageal right subclavian artery, lateral origin of the aortic arch branches, and persistent left cranial vena cava (Patterson et al., 1974).

Prevalence: Conotruncal defects in the Keeshond have been studied extensively (Werner et al., 2005).

Control: The recommendation is that affected dogs with congenital heart defects should not be bred, even if they are only mildly affected. At this time, there are neither good statistical models to predict risks nor reliable methods to detect all carriers. Dogs will the subclinical form (Grade1) are not reliably detected by clinical evaluation.

Nevertheless, a complete cardiovascular workup should be performed prior to breeding of any relatives of affected dogs. Test matings, with evaluation of all offspring, can be used to evaluate breeding animals.

Genetic testing: Not available.

Breed: Keeshond.

References


Note: the references are listed in reverse chronological order (from the most recent year to the earliest year), and alphabetically by first author within a year.
2009 Diez-Prieto, I., García-Rodríguez, B., Ríos-Granja, A., Cano-Rábano, M., Peña-Penabad, M., García, C.P. :
Cardiac conotruncal malformations in a family of beagle dogs. J Small Anim Pract 50:597-603, 2009. Pubmed reference: 19814768. DOI: 10.1111/j.1748-5827.2009.00815.x.
2005 Werner, P., Raducha, MG., Prociuk, U., Ostrander, EA., Spielman, RS., Kirkness, EF., Patterson, DF., Henthorn, PS. :
The keeshond defect in cardiac conotruncal development is oligogenic. Hum Genet 116:368-77, 2005. Pubmed reference: 15711798. DOI: 10.1007/s00439-004-1242-3.
1999 Werner, P., Raducha, M.G., Prociuk, U., Budarf, M., Henthorn, P.S., Patterson, D.F. :
Comparative mapping of the DiGeorge region in the dog and exclusion of linkage to inherited canine conotruncal heart defects Journal of Heredity 90:494-498, 1999. Pubmed reference: 10485139.
1993 Patterson, D.F., Pexieder, T., Schnarr, W.R., Navratil, T., Alaili, R. :
A Single Major-Gene Defect Underlying Cardiac Conotruncal Malformations Interferes with Myocardial Growth During Embryonic Development - Studies in the CTD Line of Keeshond Dogs American Journal of Human Genetics 52:388-397, 1993. Pubmed reference: 8430699.
1978 Patterson, DF. :
Lesion-specific genetic factors in canine congenital heart diseases: patent ductus arteriosus in poodles, defects of the conotruncal septum in the Keeshond. Birth Defects Orig Artic Ser 14:315-47, 1978. Pubmed reference: 737304.
1977 Mierop, L.H.S. van, Patterson, D.F., Schnarr, W.R. :
Hereditary conotruncal septal defects in Keeshond dogs: embryologic studies American Journal of Cardiology 40:936-950, 1977. Pubmed reference: 930841.
1974 Patterson, D.F., Pyle, R.L., Mierop, L. van, Melbin, J., Olson, M. :
Hereditary defects of the conotruncal septum in Keeshond dogs: pathologic and genetic studies American Journal of Cardiology 34:187-205, 1974. Pubmed reference: 4843154.

Edit History


  • Created by Frank Nicholas on 06 Sep 2005
  • Changed by Martha MaloneyHuss on 06 Sep 2011
  • Changed by Frank Nicholas on 07 Sep 2011
  • Changed by Vicki Meyers-Wallen on 28 Sep 2011