Recognized: October 27, 2016

WHAT IS G-6-S?

N-acetylglucosamine 6-sulfatase deficiency is an inherited metabolic defect known to occur in Nubian goats and related crosses. A mutation in the G6S gene renders the enzyme incapable of degrading complex polysaccharides which then abnormally accumulate in tissues such as central nervous system and viscera. Affected animals may exhibit a variety of symptoms including delayed motor development and growth retardation, and are not expected to live a normal lifespan.

The disease is inherited in an autosomal recessive fashion. Therefore, both sexes are equally affected and two copies of the defective gene must be present for signs of the disorder to be observed. Breeding two carrier goats, which are phenotypically normal but each possessing a single copy of the mutation, is predicted to produce 25% affected offspring. The predicted genotypic frequency for this disorder has been reported to be approximately 74.2% normal, 23.9% carrier, and 1.9% affected. G6S carrier status is determined by observation of a mutation, changing a C to T in codon 102 of the 559-amino acid G6S protein. This mutation leads to the formation of a defective, truncated protein. Testing is available at a contracted rate to all dairy goat owners through ADGA.

RATIONALE FOR POLICY

Because G6S homozygous (affected) animals may not be symptomatic prior to reproductive age, and heterozygous (carrier) animals have not been demonstrated to be symptomatic, both affected and carrier animals may reproduce and pass on the defect. Genetic testing for this disease is definitive and is available at reasonable contracted cost through ADGA.

With recognition by the ADGA Board of Directors of G6S deficiency as an undesirable genetic factor, information concerning the G6S status of potentially affected or carrier animals will become available to all dairy goat owners enabling them to limit carrier‐to‐carrier matings and manage the impact of the disorder within their herd and the dairy goat population at large.

ADGA G6S Policy

ADGA contracts for G6S testing and carrier status recording to members and the wider goat community in order to track this disease in pedigrees, to reduce its incidence, and assist in eventual eradication of the defect.  ADGA will maintain a list of approved testing laboratories, and that information as well as forms and instructions for sample submission will be provided upon request.

Upon receipt of testing results from an approved laboratory, ADGA will maintain a database of G6S testing results. Upon breeder request, G6S testing results will be included as part of the goat’s pedigree information and will become part of the animal’s permanent record in the ADGA pedigree database.