Overview
Part of the official UK Kennel Club testing scheme in Staffordshire Bull Terrier
L-2-hydroxyglutaric aciduria (L-2-HGA) is a neurometabolic disorder. Affected dogs have increased levels of L-2-hydroxyglutaric acid in urine, blood and cerebrospinal fluid, and this substance is toxic to the cells of the central nervous system. L-2-HGA produces a variety of clinical neurological deficits, including “wobbly” gait, tremors, seizures, muscle stiffness with exercise or excitement and changes in behaviour. Affected dogs begin to show signs of disease from around four months of age, but it can also be later. There is no cure or treatment for L-2-HGA.
This test for the Staffordshire Bull Terrier L-2-HGA variant.
The two single-nucleotide substitutions separated by a single invariant T nucleotide in the gene called L2HGDH that causes L-2-HGA in Staffordshire Bull Terrier is autosomal recessive. This means that dogs that carry two copies of the mutation (homozygotes) will almost certainly develop L-2-HGA during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) will not develop L-2-HGA as a result of the L2HGDH mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that will not develop L-2-HGA should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.
Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the L2HGDH mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with L-2-HGA, and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease mutation within the breed is gradually reduced.
