Evaluation of causative mutations of chondrodysplasia-like dwarfism in the Miniature Horse in Brazil

Abstract

Dwarfism is a form of abnormal development determined by genes which greatly reduce stature and may negatively impact health and reproduction. In horses, dwarfism is mainly described in the Miniature Horse. In this breed, four mutations that are independently segregated have been described in the Aggrecan gene, responsible for the chondrodysplasia-like dwarfism, an autosomal recessive disease. Recently, the genotyping of affected Miniature Horses and their parents from a herd at Sao Paulo state reinforced the hypothesis of the involvement of other mutations responsible for dwarfism in these animals besides those previously described. Therefore, the objectives of this project are: verify the already described mutations and to investigate other possible mutations related to chondrodysplasia-like dwarfism in the Brazilian Miniature Horse herd; estimate the allelic frequency of these mutations and describe the clinical findings of the affected animals. For this, affected animals and phenotypically normal Miniature Horses from farms in the state of Sao Paulo will be used to carry out these evaluations. The mRNA of the Aggrecan gene will be genotyped to verify the mutations already described and to investigate other possible mutations related to chondrodysplasia-like dwarfism. In the end, the description of the clinical signs and the mutations responsible for the disease will allow the adoption of control measures for new cases and will provide molecular tests for the disease to Brazilian breeders.