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Research article - Peer-reviewed, 2020

Characterization of a Homozygous Deletion of Steroid Hormone Biosynthesis Genes in Horse Chromosome 29 as a Risk Factor for Disorders of Sex Development and Reproduction

Ghosh, Sharmila; Davis, Brian W.; Rosengren, Maria; Jevit, Matthew J.; Castaneda, Caitlin; Arnold, Carolyn; Jaxheimer, Jay; Love, Charles C.; Varner, Dickson D.; Lindgren, Gabriella; Wade, Claire M.; Raudsepp, Terje


Disorders of sex development (DSD) and reproduction are not uncommon among horses, though knowledge about their molecular causes is sparse. Here we characterized a 200 kb homozygous deletion in chromosome 29 at 29.7-29.9 Mb. The region contains AKR1C genes which function as ketosteroid reductases in steroid hormone biosynthesis, including androgens and estrogens. Mutations in AKR1C genes are associated with human DSDs. Deletion boundaries, sequence properties and gene content were studied by PCR and whole genome sequencing of select deletion homozygotes and control animals. Deletion analysis by PCR in 940 horses, including 622 with DSDs and reproductive problems and 318 phenotypically normal controls, detected 67 deletion homozygotes of which 79% were developmentally or reproductively abnormal. Altogether, 8-9% of all abnormal horses were homozygous for the deletion, with the highest incidence (9.4%) among cryptorchids. The deletion was found in 4% of our phenotypically normal cohort, 1% of global warmblood horses and ponies, and 7% of draught breeds of general horse population as retrieved from published data. Based on the abnormal phenotype of the carriers, the functionally relevant gene content, and the low incidence in general population, we consider the deletion in chromosome 29 as a risk factor for equine DSDs and reproductive disorders.


horse; disorders of sex development; cryptorchidism; reproduction; CNV; ECA29; steroid hormone; AKR1C

Published in

2020, volume: 11, number: 3, article number: 251
Publisher: MDPI

Authors' information

Ghosh, Sharmila
Texas AandM Univ
Davis, Brian W.
Texas AandM Univ
Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics
Jevit, Matthew J.
Texas AandM Univ
Castaneda, Caitlin
Texas AandM Univ
Arnold, Carolyn
Texas AandM Univ
Jaxheimer, Jay
Texas AandM Univ
Love, Charles C.
Texas AandM Univ
Varner, Dickson D.
Texas AandM Univ
Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics
University of Leuven (KU Leuven)
Wade, Claire M.
Univ Sydney
Raudsepp, Terje
Texas AandM Univ

UKÄ Subject classification

Animal and Dairy Science

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