Neuronal Ceroid Lipofuscionsis (5)

Description

There are many forms of Neuronal Ceroid Lipofuscinosis (NCL) that result in progressive degeneration of the central nervous system (CNS). Characteristic neurological signs of NCL include:

• mental dullness
• ataxia
• loss of vision
• weakness
• abnormal gait
• seizures
• tremors
• aggressive behaviors

NCL type 5 is found in Border Collies. It was first identified in Australia in the 1980s. Additional cases of NCL in dogs were also reported in the USA in the 1990s. There are many forms of NCL. They are each assigned a number in order to describe the symptoms, which can vary. Animal Genetics tests for NCL-2, NCL-5, and NCL-10.

In 2005, a nonsense mutation of the canine CLN5 gene was reported to be linked to a specific form of Neuronal Ceroid Lipofuscinosis (NCL-5) found in Border Collies. The CLN5 gene codes for an enzyme that breaks down waste products during cell function. Due to a premature stop in the DNA, the production of this enzyme ceases, causing a build-up of waste products within the cell. This eventually causes NCL-5.

In 2016, NCL-5 was diagnosed in young adult Australian Cattle Dogs. Further studies showed that all affected individuals were identified as being homozygous (having two copies) for the nonsense mutation, which was previously linked to NCL5 in Border Collies. NCL-5 is an autosomal recessive mutation. Autosomal recessive genetic mutations are mutations that can be passed from either parent and require two copies of the gene to show symptoms. It is important to test dogs before breeding in order to identify whether or not they are carriers of NCL-5. If two carriers are bred with one another, there is a 25% chance per puppy that they will be homozygous for the NCL mutation and develop NCL.