A 20 bp Duplication in Exon 2 of the Aristaless-Like Homeobox 4 Gene (ALX4) Is the Candidate Causative Mutation for Tibial Hemimelia Syndrome in Galloway Cattle

PLoS One. 2015 Jun 15;10(6):e0129208. doi: 10.1371/journal.pone.0129208. eCollection 2015.

Abstract

Aristaless-like homeobox 4 (ALX4) gene is an important transcription regulator in skull and limb development. In humans and mice ALX4 mutations or loss of function result in a number of skeletal and organ malformations, including polydactyly, tibial hemimelia, omphalocele, biparietal foramina, impaired mammary epithelial morphogenesis, alopecia, coronal craniosynostosis, hypertelorism, depressed nasal bridge and ridge, bifid nasal tip, hypogonadism, and body agenesis. Here we show that a complex skeletal malformation of the hind limb in Galloway cattle together with other developmental anomalies is a recessive autosomal disorder most likely caused by a duplication of 20 bp in exon 2 of the bovine ALX4 gene. A second duplication of 34 bp in exon 4 of the same gene has no known effect, although both duplications result in a frameshift and premature stop codon leading to a truncated protein. Genotyping of 1,688 Black/Red/Belted/Riggit Galloway (GA) and 289 White Galloway (WGA) cattle showed that the duplication in exon 2 has allele frequencies of 1% in GA and 6% in WGA and the duplication in exon 4 has frequencies of 23% in GA and 38% in WGA. Both duplications were not detected in 876 randomly selected German Holstein Friesian and 86 cattle of 21 other breeds. Hence, we have identified a candidate causative mutation for tibial hemimelia syndrome in Galloway cattle and selection against this mutation can be used to eliminate the mutant allele from the breed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cattle
  • Cattle Diseases / diagnosis
  • Cattle Diseases / genetics*
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics*
  • Ectromelia / veterinary*
  • Exons*
  • Gene Duplication*
  • Genotype
  • Molecular Sequence Data
  • Mutation*
  • Pedigree
  • Polymorphism, Genetic
  • Sequence Alignment
  • Syndrome
  • Tibia / abnormalities*
  • Transcription Factors / chemistry
  • Transcription Factors / genetics*

Substances

  • ALX4 protein, human
  • DNA-Binding Proteins
  • Transcription Factors

Supplementary concepts

  • Absence of Tibia

Grants and funding

This work was supported by a grant of the Erxleben Research & Innovation Council to BB (ERIC-BR1959-2013-01). Veterinary Practice Zettlitz provided support in the form of a salary for author MF, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of all authors are articulated in the "author contributions" section.