Genotyping Brahman cattle for generalised glycogenosis

Area of Science:

• Veterinary Genetics
• Animal Breeding
• Molecular Diagnostics

Background:

• Generalized glycogenosis is a genetic disorder affecting Brahman cattle.
• Accurate genotyping is crucial for managing genetic diseases in livestock populations.
• Previous methods for identifying disease-causing alleles were less reliable.

Purpose of the Study:

• To develop reliable PCR procedures for genotyping Brahman cattle for specific loss-of-function alleles.
• To assess the prevalence and risk of generalized glycogenosis in Australian Brahman cattle populations.
• To improve genetic selection strategies for reducing disease incidence.

Main Methods:

• Development of PCR assays targeting three loss-of-function alleles in the acidic alpha-glucosidase gene.
• Assays utilized internal restriction sites, independent of allelic variants.
• Genotyping of over 8,500 clinically normal Brahman cattle.

Main Results:

• The common 1057deltaTA mutation (E7) was found in 16.4% of Brahman cattle.
• A less common 1783T mutation (E13) was identified in descendants of a single imported bull.
• A silent polymorphism (2223G-->A) associated with the disease was present in 18% of cattle.
• A third allele, 1351T (E9), found in 15% of cattle, reduces enzyme activity but is not linked to clinical disease.
• All identified disease-associated alleles originated from imported USA Brahman cattle.

Conclusions:

• The developed PCR assays offer improved reliability and accuracy for genotyping.
• These assays facilitate precise genetic selection against the 1057deltaTA and 1783T alleles.
• Implementation of these methods will reduce the incidence of generalized glycogenosis in Brahman herds.