CL Test for Neuronal Ceroid Lipofuscinosis
For: Border Collies
The OptiGen CL test is a DNA-based test that provides a method to identify the Border Collie neuronal ceroid lipofuscinosis disease gene, commonly referred to as CL, inherited as a recessive genetic defect. This test allows you to control the CL gene frequency in your line so you can prevent producing puppies affected with the disease. Among lines of Australian descent, it is estimated that up to 3% of Border Collies are carriers and about 1 in 1000 matings will produce affected pups.
Besides Border Collies, a type of neuronal ceroid lipofuscinosis disease has been described in English Setters, Tibetan Terriers and American Bulldogs. It has also been identified in human, cow, horse, sheep and mouse. There are several (at least seven) different genes known to result in a specific form of the disease. The OptiGen CL test is specific for the Border Collie and detects the CL genetic status in Border Collies only.
Reliable identification of dogs that do not carry disease genes is the key to controlling autosomal recessive diseases. The OptiGen CL test enables accurate identification of these dogs. Called "genetically clear," "noncarriers" or, more formally, "homozygous normals," such dogs can pass only the normal gene on to all their pups - which means that none of their pups can ever be affected with CL. These "clear" dogs can be bred to any mate, even to a CL carrier which may be a desirable breeding prospect for other reasons.
Homozygous means both copies of the gene in your dog are the SAME - both normal or both CL. A carrier has one normal and one CL gene, referred to as heterozygous.
Because the OptiGen CL test is a mutation-based gene test, it accurately and specifically identifies normal dogs, carriers (heterozygous dogs) and affecteds. Possible test results are listed in the table below.
Neuronal ceroid lipofuscinosis is a type of lysosomal storage disorder that results in accumulation of lysosomal storage bodies in the cells of many tissues of the affected animal. This leads to progressive neurodegeneration (degeneration of brain and eye cells) and results in severe neurological impairment and early death. Affected dogs appear normal at birth, but begin to exhibit symptoms early in life – around 1- 2 years of age. The age of onset and severity of the disease can vary greatly among individuals. The symptoms include progressive motor decline with seizures and loss of coordinated muscle movements, cognitive decline and abnormal behavior. Visual impairment may occur. Due to the severity of the disease, affected Border Collies rarely survive beyond 26-28 months. There is no treatment or cure at this time.
|Possible results using the OptiGen CL test|
|N =||Normal (Clear)||Homozygous for normal gene, so will never develop the disease|
|C =||Carrier ||Carries one disease gene, but will never develop the disease|
|A =||Affected||Homozygous for disease gene and will develop the disease|
The following table highlights all the breedings that will not produce affected pups. These breedings include at least one parent proven "normal" by the OptiGen CL test. All other breedings are at risk of producing CL-affected pups. It isn't necessary to remove any dog from the breeding population. But when choosing pups to retain as potential breeding stock, it is important to select for dogs proven "normal" by the OptiGen CL test and select against dogs proven to be carriers. Pups can be tested to distinguish carriers from normals as soon as they are old enough to have a small blood sample collected.
|Expected results of breeding strategies using the OptiGen mutation tests for recessive diseases|
|Parent 1 |
|Parent 2 Status|
|Normal||All = Normal||1/2 = Normal|
1/2 = Carrier
|All = Carrier|
|Carrier||1/2 = Normal|
1/2 = Carrier
|1/4 = Normal|
1/2 = Carrier
1/4 = Affected
|1/2 = Carrier|
1/2 = Affected
|Affected||All = Carrier||1/2 = Carrier|
1/2 = Affected
|All = Affected|
The research leading to this discovery was undertaken by scientists at the University of New South Wales, Sydney, Australia. Data are published in Genomics, July 18, 2005 (Electronic Publication). The patent-pending technology underlying this test is under exclusive license to OptiGen for the U.S. and Canada, and non-exclusive license elsewhere. Background information for this article was obtained from Dr. Alan Wilton, UNSW (http://www.science.unsw.edu.au - search for “Border Collie”) and the Border Collie Club of NSW (www.bccnsw.com).