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Hypophosphatasia (HPP) - Karelian Bear Dog
| Acronym: | HPP |
| Gene: | ALPL |
| Mutation: | c.1301T>G |
| Inheritance: | Autosomal Recessive |
| Sample type: | CHS (Cheek Swab), WBE (Whole Blood EDTA) |
Genetics and characteristics
Hypophosphatasia (HPP) is an inherited (genetic) skeletal disorder that affects the bone and cartilage tissues in various mammalian species including dogs and humans. In dogs the symptoms range from mild to severe and usually develop over the first two months after birth. They include growth retardation, movement difficulties, crouched stance, reluctance to move, generalized muscle weakness, deformed elbow joints, hyperextension of distal joints, fractures, respiratory failure and seizures. HPP in many cases leads to death or reduced quality of life that warrants euthanasia. In Karelian Bear Dogs HPP is caused by a genetic missense mutation (a base pair substitution) in the ALPL gene that encodes the enzyme alkaline phosphatase present in bones, the liver and kidneys. The mutated form of the enzyme results in various bone related metabolic abnormalities leading to skeletal hypomineralization and ossification defects.
HPP is inherited as an autosomal recessive trait. This means that two copies of the mutated gene are required for the disease to develop. Karelian Bear Dogs with only one copy of the mutated gene won’t develop the disease but act as carriers that can potentially pass the mutation to their offspring. Early detection by genetic testing can identify Karelian Bear Dogs that carry the mutation and inform the breeders’ decisions when selecting mating pairs. This can be used to avoid unintentional breeding of infected puppies.
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:
Kyöstilä, K., Syrjä, P., Lappalainen, A.K. et al. A homozygous missense variant in the alkaline phosphatase gene ALPL is associated with a severe form of canine hypophosphatasia. Sci Rep 9, 973 (2019). https://doi.org/10.1038/s41598-018-37801-2