A LINE-1 insertion in DLX6 is responsible for cleft palate and mandibular abnormalities in a canine model of Pierre Robin sequence.
Cleft palate (CP) is one of the most commonly occurring craniofacial birth defects in humans. In order to study cleft palate in a naturally occurring model system, we utilized the Nova Scotia Duck Tolling Retriever (NSDTR) dog breed. Micro-computed tomography analysis of CP NSDTR craniofacial structures revealed that these dogs exhibit defects similar to those observed in a recognizable subgroup of humans with CP: Pierre Robin Sequence (PRS). We refer to this phenotype in NSDTRs as CP1. Individuals with PRS have a triad of birth defects: shortened mandible, posteriorly placed tongue, and cleft palate. A genome-wide association study in 14 CP NSDTRs and 72 unaffected NSDTRs identified a significantly associated region on canine chromosome 14 (24.2 Mb-29.3 Mb; p(raw )= 4.64 × 10(-15)). Sequencing of two regional candidate homeobox genes in NSDTRs, distal-less homeobox 5 (DLX5) and distal-less homeobox 6 (DLX6), identified a 2.1 kb LINE-1 insertion within DLX6 in CP1 NSDTRs. The LINE-1 insertion is predicted to insert a premature stop codon within the homeodomain of DLX6. This prompted the sequencing of DLX5 and DLX6 in a human cohort with CP, where a missense mutation within the highly conserved DLX5 homeobox of a patient with PRS was identified. This suggests the involvement of DLX5 in the development of PRS. These results demonstrate the power of the canine animal model as a genetically tractable approach to understanding naturally occurring craniofacial birth defects in humans.
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America.
Zena T
ZT
Wolf
Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States of America.
Elizabeth J
EJ
Leslie
Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America.
Boaz
B
Arzi
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America.
Kartika
K
Jayashankar
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America.
Nili
N
Karmi
Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States of America; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, China; Department of Cleft Lip and Palate Surgery, West China Hospital of Stomatology, Sichuan University, Chengdu, China.
Zhonglin
Z
Jia
Center for Molecular and Genomic Imaging, University of California, Davis, Davis, California, United States of America.
Douglas J
DJ
Rowland
Department of Animal Science, University of California, Davis, Davis, California, United States of America.
Amy
A
Young
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America.
Noa
N
Safra
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America.
Saundra
S
Sliskovic
Department of Pediatrics, University of Iowa, Iowa City, Iowa, United States of America.
Jeffrey C
JC
Murray
Faculty of Veterinary Science, University of Sydney, Sydney, New South Wales, Australia.
Claire M
CM
Wade
Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, Davis, California, United States of America.
Danika L
DL
Bannasch
D000818:Animals; D002972:Cleft Palate / Q000235:genetics*; D004285:Dogs; D005787:Gene Frequency / Q000235:genetics; D005801:Genes, Homeobox / Q000235:genetics*; D055106:Genome-Wide Association Study / Q000379:methods; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics*; D008334:Mandible / Q000378:metabolism; D020125:Mutation, Missense / Q000235:genetics; D010641:Phenotype; D010855:Pierre Robin Syndrome / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide / Q000235:genetics
D018398:Homeodomain Proteins