« Previous AbstractProof of concept for the use of trained sniffer dogs to detect osteosarcoma    Next AbstractThe plant is crucial: specific composition and function of the phyllosphere microbiome of indoor ornamentals »

J Dairy Sci

Title:		Truncation of IFT80 causes early embryonic loss in Holstein cattle associated with Holstein haplotype 2
Author(s):		Ortega MS; Bickhart DM; Lockhart KN; Null DJ; Hutchison JL; McClure JC; Cole JB;
Address:		"Division of Animal Sciences, College of Agriculture, Food, and Natural Resources, University of Missouri, Columbia 65211. Cell Wall Biology and Utilization Research Laboratory, U.S. Dairy Forage Research Center, Agricultural Research Service, United States Department of Agriculture, Madison, WI 53706. Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705-2350. Animal Genomics and Improvement Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705-2350. Electronic address: john.cole@urus.org"
Journal Title:		J Dairy Sci
Year:		2022
Volume:		20220907
Issue:		11
Page Number:		9001 - 9011
DOI:		10.3168/jds.2022-21853
ISSN/ISBN:		1525-3198 (Electronic) 0022-0302 (Linking)
Abstract:		"Recessive alleles represent genetic risk in populations that have undergone bottleneck events. We present a comprehensive framework for identification and validation of these genetic defects, including haplotype-based detection, variant selection from sequence data, and validation using knockout embryos. Holstein haplotype 2 (HH2), which causes embryonic death, was used to demonstrate the approach. Holstein haplotype 2 was identified using a deficiency-of-homozygotes approach and confirmed to negatively affect conception rate and stillbirths. Five carriers were present in a group of 183 sequenced Holstein bulls selected to maximize the coverage of unique haplotypes. Three variants concordant with haplotype calls were found in HH2: a high-priority frameshift mutation resulting, and 2 low-priority variants (1 synonymous variant, 1 premature stop codon). The frameshift in intraflagellar 80 (IFT80) was confirmed in a separate group of Holsteins from the 1000 Bull Genomes Project that shared no animals with the discovery set. IFT80-null embryos were generated by truncating the IFT80 transcript at exon 2 or 11 using a CRISPR-Cas9 system. Abattoir-derived oocytes were fertilized in vitro, and zygotes were injected at the one-cell stage either with a guide RNA and CAS9 mRNA complex (n = 100) or Cas9 mRNA (control, n = 100) before return to culture, and replicated 3 times. IFT80 is activated at the 8-cell stage, and IFT80-null embryos arrested at this stage of development, which is consistent with data from mouse hypomorphs and HH2 carrier-to-carrier matings. This frameshift in IFT80 on chromosome 1 at 107,172,615 bp (p.Leu381fs) disrupts WNT and hedgehog signaling, and is responsible for the death of homozygous embryos"
Keywords:		"Animals;Cattle Male Animals Mice Haplotypes *Hedgehog Proteins/genetics/metabolism *Codon, Nonsense RNA, Guide, Kinetoplastida Homozygote Carrier Proteins Holstein cattle embryonic loss gene editing genetic defects;"
Notes:		"MedlineOrtega, M Sofia Bickhart, Derek M Lockhart, Kelsey N Null, Daniel J Hutchison, Jana L McClure, Jennifer C Cole, John B eng 2022/09/10 J Dairy Sci. 2022 Nov; 105(11):9001-9011. doi: 10.3168/jds.2022-21853. Epub 2022 Sep 7"