Abstract
Autosomal dwarfism (adw) in chickens is a growth deficiency caused by a recessive mutation. Characteristic for adw is an approximately 30% growth reduction with short shank. The adw variant was first recognized in the Cornell K-strain of White Leghorns, but the genetic causal variant remained unknown. To identify the causal variant underlying the adw phenotype, fine mapping was conducted on chromosome 1, within 52–56 Mb. This region was known to harbor the causal variant from previous linkage studies. We compared whole-genome sequence data of this region from normal-sized and adw chickens in order to find the unique causal variant. We identified a novel nonsense mutation NP_001006244.1:p.(Trp59∗), in the transmembrane protein 263 gene (TMEM263), completely associated with adw. The nonsense mutation truncates the transmembrane protein within the membrane-spanning domain, expected to cause a dysfunctional protein. TMEM263 is reported to be associated with bone mineral deposition in humans, and the protein shows interaction with growth hormone 1 (GH1). Our study presents molecular genetic evidence for a novel loss-of-function variant, which likely alters body growth and development in autosomal dwarf chicken.
Highlights
Short body stature, known as dwarfism, is a condition of growth deficiency and reduced body weight caused by a variety of hereditary and hormonal disruptions
The runs of homozygosity (ROH) overlaps with the location of the candidate region (Supplementary Figure S1) most likely as a consequence of the strong selection for the adw haplotype in the chicken lines used
We found 146,070 variants, including genic variants in 72 genes and intergenic variants; we did not observe any specific structural variants that could contribute to growth reduction, as they were not located in the coding region
Summary
Known as dwarfism, is a condition of growth deficiency and reduced body weight caused by a variety of hereditary and hormonal disruptions. Various short body statures have been investigated in animal species including dogs, cattle, pigs, and chickens (Boegheim et al, 2017). Dwarf animals in native or commercial breeds, have held the interest of humans over the past century, and have been bred for either ornamental or economic reasons. Plenty of distinct dwarf phenotypes have been described and studied in the chicken literature (Hutt, 1949). One of the best-studied hereditary variations in growth deficiency is sex-linked dwarfism, which is a disproportional dwarfism, caused by the mutation in the GHR (Burnside et al, 1991; Agarwal et al, 1994)
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