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Dry Eye Curly Coat Syndrome (CCS)
| Acronym: | CCS, CKCSID |
| Gene: | FAM83H |
| Mutation: | c.977del |
| Inheritance: | Autosomal recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Dry eye curly coat syndrome is a congenital disorder that manifests as a rough coat present at birth, with keratoconjunctivitis sicca apparent on eyelid opening at 10–14 days, followed by hyperkeratinization of footpads and distortion of nails that develops over the next few months. It is caused by a deletion in the FAM83H gene, which has an important role in skin development and regulation, in addition to enamel formation. The mutation is recessive and heterozygous dogs do not have a discernable phenotype.
In a report from 2012, of DNA testing of 280 cavaliers, the UK’s Animal Health Trust researchers estimate that 10.8% of Cavalier King Charles Spaniel are carriers of dry eye curly coat syndrome, and 0.4% are affected. It includes a very severe form of dry eye syndrome, but it is to be distinguished from the much more common form of dry eye in the Cavalier King Charles Spaniel breed. No cases of curly coat syndrome with severe dry eye have been reported in any other breed.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Forman, O.P., Penderis, J., Hartley, C., Hayward, L.J., Ricketts, S.L., and Mellersh, C.S. (2012). Parallel mapping and simultaneous sequencing reveals deletions in BCAN and FAM83H associated with discrete inherited disorders in a domestic dog breed. PLoS Genet. 8, e1002462.