BVMS PhD DipECVN MRCVS RCVS and European Specialist in Veterinary Neurology

Research in syringomyelia
Initiatives and collaborations from the Stone Lion Veterinary Centre

 

The search for the genes – work on the genotype

 

Background
After Clare Rusbridge initially described the disease in a letter to the Veterinary Record in 1997, work began on advancing our understanding it. Research assistant Penny Knowler became involved when it became apparent that the work involved was more than one person could possibly hope to do - especially when working in her spare time.

 

Finding the gene (s) for syringomyelia

 

STEP 1 – constructing a genealogy

Penny Knowler constructed a genealogy of ~ 11,000 related CKCS dogs spanning 24 generations from over 700 MRI confirmed dogs. She also established a DNA collection of over 1,500 samples with phenotypic information specific for Chiari-like malformation and Syringomyelia but also with information on Mitral Valve Disease and Epilepsy. All this phenotypical information is linked to the genealogical information on an Access database.

 

This worldwide collection known as ‘DNA for Healthy Cavaliers’ was sponsored by Cavalier Health Foundation (USA), the UK DNA Archive for Companion Animals , Boehringer Ingelheim UK and UK CKCS Club, Utrecht University, Dr Guy Rouleau’s Laboratory McGill University and TDDS Laboratories.

 

The campaign was/is supported by a huge number of dedicated dog owners, breeders and veterinarians from Europe (particularly from Netherlands) USA, Australia and South Africa. It is thanks to the variety of imaginative initiatives that this research has been possible in particular. Sandy Smith’s book ‘For the Love of Ollie’, Christi Scarpino, Kendall Barker CavalierTalk Members, The Cavalier Friends, Rainbow Paws and The Syringomyelia Cavalier Collection Scheme


For more information about received donations click here

STEP 2 – Establishing links with a geneticist


In 2003 Dr Guy Rouleau agreed to take the research forward, appointing Dr Zoha Kibar to oversee the mammoth task of finding the gene. Dr Rouleau’s laboratory was initially at Mc Gill University but has since moved to CHU Sainte Justine Research Centre in Montreal of which Dr Rouleau is the director.

STEP 3 – Archiving CKCS DNA


In 2004 in collaboration with Dr Guy Rouleau at McGill University and Dr Berge Minassian at Sick Kids Toronto a grant from Cavalier Health Foundation (#104)  was approved to archive Cavalier DNA to be used in a genome scan

STEP 4 – Establishing if a genome scan is viable


It is possible that a breed is so inbred that finding the abnormal gene is not achievable by usual routes because the dogs are so genetically similar (i.e. like clones). Fortunately this proved not to be the case in the CKCS. At the Mammalian Genotyping Service at Marshfield Clinic, Wisconsin USA, 10 dogs were genotyped with 122 markers to evaluate if there was genetic diversity. This found an average PIC of 0.42 and average heterozygosity of 0.46 meaning that whole genomes scan is feasible.

What is still needed?

 
1. The CM/SM genome research team are actively seeking DNA from CKCS over five years old that do not have syringomyelia (must have had a MRI scan when 5 years old or older)
2. DNA from Griffon Bruxellois over 2 years old which have had a brain and cervical MRI
3. DNA from other breeds / species with a diagnosis of CM/SM  
If applicable please contact: penny.knowler@ntlworld.com

STEP 5 – Linkage mapping of the SM gene(s) in the CKCS breed.


A whole genome scan was completed in 2005 with 173 CKCS dogs selected based on SM-affected status and familial relationship in the CKCS database. The dogs were distributed over 34 dog pedigrees and including multiple affected and unaffected siblings and half siblings with their parents. The genome scan utilised 249 microsatellite markers distributed over the 28 autosomes and the X chromosome
Dr Marie-Pierre Dube, from the University of Montreal undertook the Two-point linkage analysis using the LODPAL routine from SAGE (Statistical analysis for genetic epidemiology).The conclusion of this initial scan was the identification of six genomic regions that could harbour the CM/SM gene(s).

STEP 6 – Fine Mapping


Dr Kibar is now undertaking the fine mapping of the six genomic regions in a larger sample size and is funded by a grant from the American Kennel Club Health Foundation (#954) with matching funds provided by ACKCSC and Cavalier Club of the USA.  Additional DNA samples have been provided by North Carolina University and Guelph University in conjunction with their own investigations into CM/SM. A new whole genomes scan using the innovative canine SNP (or single nucleotide polymorphisms) genotyping technology is planned in the near future. The candidate genetic interval(s) identified in both genome scans will be narrowed down using genetic studies in the CKCS and other related breeds affected with CM/SM. Once the candidate genomic region(s) have been well defined, the positional candidate gene approach will be used to identify the defective gene(s) in CM/SM.

Finding the gene(s) for Chiari malformation


Investigation of possible candidate gene - Fibrillin 1

Genetic studies in humans with Chiari malformation type 1 have indicated significant areas (high LOD scores) on chromosomes 9 and 15 (for more information click here). On chromosome 15 there is a very large gene called Fibrillin- 1 which has already been associated with genetic conditions that involve mis-shapen skulls including Marfan syndrome and Shprintzen-Goldberg syndrome (the defects in this syndrome include CM). Fibrillin has been suggested as a possible positional candidate gene. It is very large gene coding for an amino acid which is a constitutive element of extracellular microfibrils in connective tissues. Fibrillin 1 sequence analysis in affected CKCS, Yorkshire Terrier, Bull Terrier, Boston Terrier, Chihuahua, Brussels Griffon and King Charles breeds is ongoing.

SNP Genotyping and Statistical Genetic Analysis in Brussels Griffons

In 2005, Clare and Penny were asked by breeders Lee Pieterse (Australia) and Meg Prior (USA) to investigate CM/SM in the Griffon Bruxellois. With the support of many Griffon Bruxellois breeders across the globe, the team were able to construct a genealogy and DNA archive. A genome-wide scan for the CM gene(s) in The Griffon Bruxellois using the CanineSNP20 BeadChip  developed by Illumina was recently completed under the supervision and expertise of Dr Sarah Blott at the Animal Health Trust Dr Blott was also responsible for initial genetic analysis of the data.

Fine Mapping and Candidate gene analysis

Fine Mapping and Candidate gene analysis
The work on the Griffon Bruxellois DNA continues with detailed analysis of genes residing in regions highlighted by SNP Genotyping.

 

Finding the gene/s responsible for CM/SM will help better understand the underlying molecular and cellular pathogenic mechanisms for better diagnosis, prognosis and clinical management of the conditions. Most importantly it will be possible to develop a genetic test to identify carriers and devise breeding strategies to reduce or eliminate this devastating condition in the CKCS and other affected breeds.

Understanding the disease - work on the phenotype

 

Ongoing

CM/SM in Griffon Bruxellois - MRI, Clinicopathology and Prevalence (Georgia University, Clare Rusbridge and Penny Knowler) funded by the American Kennel Club Canine Health Foundation. This collaborative project with Georgia University will provide essential additional phenotypic information in addition to DNA.

Pathology of CM / SM - (Cambridge University and Clare Rusbridge). This initiative was the concept of breeder Margaret Carter who recognised the need for researchers to have tissue for pathological and genetic studies. Pancreatic and heart valve tissue is also be collected and passed on to other research studies. This project is funded and coordinated by Margaret Carter and The Syringomyelia Cavalier Collection Scheme

 

Cerebrospinal fluid abnormalities in syringomyelia - A multicenter study (Stone Lion Veterinary Centre, Royal Veterinary College and Cambridge University) which is part funded by the UK CKCS club

 

Comparison between skull and brain volume in syringomyelia affected and unaffected Cavaliers (Royal Veterinary College and Clare Rusbridge) which is part funded by the Cavalier Friends


Effect on positioning on MRI appearance of Chiari-like malformation -(Cambridge University and Clare Rusbridge). Project is completed - results are being analysed by Cambridge University resident. The UK CKCS Club 
provided funds to enable 24 Cavaliers to have diagnostic MRI scans the results of which were used in this project.

  
CT studies on spaniels with and without CM/SM. Pilot study is completed. Part funded by the Cavalier KCS Club of Victoria, The British Natural History Museum and the Museum of Berne.


Completed and awaiting publication

 

Chiari-like Malformation in the Griffon Bruxellois


Chiari-like Malformation in the Griffon Bruxellois Rusbridge C, Knowler SP, Pieterse L, McFadyen A. K Journal of Small Animal Practice 2009 Awaiting Publication Funded by private donations from Griffon Bruxellois breeders and from the “For the Love of Ollie” and “DNA for Healthy Cavaliers” fund.


Comparison between skull and brain volume in Cavaliers


Chiari-like Malformation in Cavalier King Charles Spaniels: volumetric comparison, Cross HR, Cappello R. Rusbridge C 2009 Submitted
 
Skull verus vertebral canal size
Association between cervical and intracranial dimensions and syringomyelia in the Cavalier King Charles spaniel Carruthers H, Rusbridge C, Dubé, M-P, Holmes M, Jeffery ND. 2009  Submitted. Funded by Cambridge University Clinical Research Outreach Program


Completed and published

 

Upper neck anatomy / abnormalities in particular atlantoaxial subluxation

 

Radiographic morphology of the cranial portion of the cervical vertebral column in Cavalier King Charles Spaniels and its relationship to syringomyelia. Stalin CE, Rusbridge C, Granger N, Jeffery ND. Am J Vet Res. 2008 Jan;69(1):89-93. Funded by Cambridge University Veterinary School and Goddard Veterinary Group.

 

Dorsal dens angulation and a Chiari type malformation in a Cavalier King Charles Spaniel. Bynevelt M, Rusbridge C, Britton J. Vet Radiol Ultrasound. 2000 Nov-Dec;41(6):521-4.

 

Relationship between syringomyelia and pain

 

Syringomyelia in cavalier King Charles spaniels: the relationship between syrinx dimensions and pain. Rusbridge C, Carruthers H, Dubé MP, Holmes M, Jeffery ND. J Small Anim Pract. 2007 Aug;48(8):432-6. Epub 2007 Jun 30.
Funded by Cambridge University Clinical Research Outreach Program

 

First descriptions of the disease

 

Coexistence of occipital dysplasia and occipital hypoplasia/syringomyelia in the cavalier King Charles spaniel. Rusbridge C, Knowler SP. J Small Anim Pract. 2006 Oct;47(10):603-6.

 

Syringomyelia: current concepts in pathogenesis, diagnosis, and treatment. Rusbridge C, Greitz D, Iskandar BJ. J Vet Intern Med. 2006 May-Jun;20(3):469-79. Review.

 

Neurological diseases of the Cavalier King Charles spaniel. Rusbridge C. J Small Anim Pract. 2005 Jun;46(6):265-72. Review.

 

Syringohydromyelia in Cavalier King Charles spaniels. Rusbridge C, MacSweeny JE, Davies JV, Chandler K, Fitzmaurice SN, Dennis R, Cappello R, Wheeler SJ. J Am Anim Hosp Assoc. 2000 Jan-Feb;36(1):34-41.

 

Background work for genome studies

 

Inherited occipital hypoplasia/syringomyelia in the cavalier King Charles spaniel: experiences in setting up a worldwide DNA collection. Rusbridge C, Knowler P, Rouleau GA, Minassian BA, Rothuizen J. J Hered. 2005;96(7):745-9. Epub 2005 Jun 15.

 

Inheritance of occipital bone hypoplasia (Chiari type I malformation) in Cavalier King Charles Spaniels. Rusbridge C, Knowler SP. J Vet Intern Med. 2004 Sep-Oct;18(5):673-8. Review.

 

Hereditary aspects of occipital bone hypoplasia and syringomyelia (Chiari type I malformation) in cavalier King Charles spaniels. Rusbridge C, Knowler SP. Vet Rec. 2003 Jul 26;153(4):107-12.


Treating the disease


Ongoing

 

Multicentre trial placebo control using novel neurogenic analgesic (Royal Veterinary College and Stone Lion Veterinary Centre) Study is completed and results are being analysed.

 

Completed and Published

 

Surgical management
Chiari-like malformation with syringomyelia in the Cavalier King Charles spaniel: long-term outcome after surgical management. Rusbridge C. Vet Surg. 2007 Jul;36(5):396-405. Part funded by the Goddard Veterinary Group

 

Medical management
Pathophysiology and treatment of neuropathic pain associated with syringomyelia. Rusbridge C, Jeffery ND. Vet J. 2008 Feb;175(2):164-72. Epub 2007 Feb 20. Review.

Stone Lion Veterinary Hospital, Goddard Veterinary Group, 41 High Street Wimbledon Common London SW19 5AU

Email: CRusbridge@goddardvetgroup.co.uk

Telephone: 020 8946 4228, Fax: 020 8944 0871

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