1
|
Bellone RR, Tanaka J, Esdaile E, Sutton RB, Payette F, Leduc L, Till BJ, Abdel-Ghaffar AK, Hammond M, Magdesian KG. A de novo 2.3 kb structural variant in MITF explains a novel splashed white phenotype in a Thoroughbred family. Anim Genet 2023; 54:752-762. [PMID: 37697831 DOI: 10.1111/age.13352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 07/12/2023] [Accepted: 08/19/2023] [Indexed: 09/13/2023]
Abstract
Splashed white in horses is characterized by extensive white patterning on the legs, face and abdomen and may be accompanied by deafness. To date, seven variants in microphthalmia-associated transcription factor (MITF) and two variants in Paired Box 3 (PAX3) have been identified to explain this phenotype. A splashed white Thoroughbred stallion, whose sire and dam were not patterned, was hypothesized to have a de novo variant leading to his white coat pattern. A whole-genome sequencing candidate gene approach identified two single nucleotide variants (SNVs) in SOX10, four SNVs in MITF and a 2.3 kb deletion in MITF with the alternative allele present in this stallion but absent in the other 18 horses analyzed. All six SNVs were annotated as modifiers and were not further considered. The deletion in MITF (NC_009159.3:g.21555811_21558139delinsAAAT) encompasses exon 9 encoding a part of the helix-loop-helix domain required for DNA binding. Sanger sequencing and parentage testing confirmed that this deletion was a de novo mutation of maternal origin. Consistent with the published nomenclature, we denote this likely causal variant as SW8. Genotyping three of this stallion's offspring identified SW8 only in the nearly all-white foal that was confirmed deaf by brainstem auditory evoked response testing. This foal was also a compound heterozygote for dominant white variants (W20/W22), but to date, W variants alone have not been connected to deafness. SW8 marks the fourth de novo MITF variant in horses reported to cause white patterning. The link between deafness and all MITF variants with and without other variants impacting melanocyte development and function needs to be further explored.
Collapse
Affiliation(s)
- R R Bellone
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
- Department of Population Health and Reproduction, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - J Tanaka
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - E Esdaile
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - R B Sutton
- Cell Physiology and Molecular Biophysics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas, USA
| | - F Payette
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania School of Veterinary Medicine, University School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - L Leduc
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania School of Veterinary Medicine, University School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - B J Till
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - A K Abdel-Ghaffar
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - M Hammond
- Veterinary Genetics Laboratory, School of Veterinary Medicine, UC Davis, Davis, California, USA
- Department of Population Health and Reproduction, School of Veterinary Medicine, UC Davis, Davis, California, USA
| | - K G Magdesian
- Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, California, USA
| |
Collapse
|
2
|
Colbert T, Till BJ, Tompa R, Reynolds S, Steine MN, Yeung AT, McCallum CM, Comai L, Henikoff S. High-throughput screening for induced point mutations. Plant Physiol 2001; 126:480-4. [PMID: 11402178 PMCID: PMC1540114 DOI: 10.1104/pp.126.2.480] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Affiliation(s)
- T Colbert
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | | | | | | | | | | | | | | | | |
Collapse
|