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Neuronal Ceroid Lipofuscinosis 7 (NCL7) – Chihuahua and Chinese Crested Dog Type
| Acronym: | NCL7 |
| Gene: | MFSD8 |
| Mutation: | c.846del |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Neuronal Ceroid Lipofuscinosis 7 (NCL7) is a genetic neurodegenerative disease characterized by an excessive accumulation of lipopygments in tissues. The accumulation in neurons and other cell types is usually caused by the lack of one of several enzymes necessary for the lipopygments normal breakdown due to mutation in genes that encode them. Several types of NCL have been identified in dogs so far and can lead to symptoms that include progressive cognitive decline, motor impairment, vision loss, seizures, progressive brain atrophy, and hence, premature death. The type of NCL found in Chihuahua and Chinese Crested dogs is caused by a deletion in the MFSD8 gene. MFSD8 is a member of the family of mammalian major facilitator superfamily (MFS) proteins that move certain molecules within a cell or in and out of cells. MFSD8 is embedded in the membrane of cell compartments called lysosomes that play an important role in digesting and recycling different types of molecules.
The type of Neuronal Ceroid Lipofuscinosis 7 (NCL7) found in Chihuahua and Chinese Crested dogs is inherited as an autosomal recessive disease, meaning two copies of the mutated gene are required for the disease to develop. Dogs with only one copy of the mutated gene will not develop the disease but may act as carriers and pass the mutation to their offspring. Early detection by genetic testing can identify carriers and help breeders in selecting future mating pairs.
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:
Guo, J., O Brien, D. P., Mhlanga-Mutangadura, T., Olby, N. J., Taylor, J. F., Schnabel, R. D., Katz, M. L., Johnson, G. S. (2015). A rare homozygous MFSD8 single-base-pair deletion and frameshift in the whole genome sequence of a Chinese Crested dog with neuronal ceroid lipofuscinosis. BMC veterinary research, 10, 960. https://doi.org/10.1186/s12917-014-0181-z
Ashwini, A., D Angelo, A., Yamato, O., Giordano, C., Cagnotti, G., Harcourt-Brown, T., Mhlanga-Mutangadura, T., Guo, J., Johnson, G. S., Katz, M. L. (2016). Neuronal ceroid lipofuscinosis associated with an MFSD8 mutation in Chihuahuas. Molecular genetics and metabolism, 118(4), 326–332. https://doi.org/10.1016/j.ymgme.2016.05.008
Karli, P., Oevermann, A., Bauer, A., Jagannathan, V., Leeb, T. (2016). MFSD8 single-base pair deletion in a Chihuahua with neuronal ceroid lipofuscinosis. Animal genetics, 47(5), 631. https://doi.org/10.1111/age.12449