Statistics from Altmetric.com
IN a study summarised on p 492 of this issue of Veterinary Record, Bruce Cattanach and collaborators from four institutions remind us of the importance of old-fashioned pedigree analysis in moderating conclusions drawn from molecular genetic analysis (Cattanach and others 2015). In this study, they used comprehensive pedigree analysis of a large proportion of the show population of boxer dogs to suggest that a mutation that has been thought to be the cause of a monogenic disease and has been treated as such in two commercial genetic testing laboratories is in fact not causal, but simply linked to the disease. What are the causes and consequences of this conclusion?
We have become familiar with the idea that one approach to eliminating inherited diseases is to find the mutation and develop a DNA test. In the veterinary world, and in particular for dogs and other companion animals, this test is then offered to breeders to apply to individuals in the affected population, usually consisting of a single breed or a number of defined breeds. When combined with the correct advice, such testing can very quickly reduce or even eliminate the disease. Over 400 such tests (across all breeds) are now available worldwide. Testing laboratory data from the UK and the USA suggest that there have been remarkable reductions in copper toxicosis in Bedlington terriers, canine leucocyte adhesion deficiency (CLAD) in Irish setters, a number of progressive retinal atrophies, primary lens luxation and several other diseases, which can be credited in whole or part to the availability of these tests.
We have also become familiar with some limitations of the tests. Tests available at the moment are directed at diseases with monogenic inheritance, while the majority of inherited disease problems are polygenic in nature, often with additional substantial environmental components. But …