Clinical course of pyruvate kinase deficiency in Abyssinian and Somali cats

Pyruvate kinase deficiency mutant gene carriage in stray cats and rescued cats from animal hoarding in Hokkaido, Japan

The mutant allele frequency of the Pyruvate kinase (PK) gene has been investigated mostly in pure breed cats. We investigated the PK mutant gene in stray and animal hoarding mongrel cats in Hokkaido, Japan. We also investigated the kinship of individuals carrying the mutant gene. Genotyping was conducted using the previously reported real-time PCR method. Fourteen microsatellite markers were used to identify the parents and offspring of cats carrying the PK mutant gene, and some kinship such as parent-offspring and siblings was observed. Some stray and animal hoarding cats carried the PK mutation gene and that consanguinity was confirmed among these cats indicated that the PK mutation gene was spread by unregulated interbreeding.

Genetic epidemiology of blood type, disease and trait variants, and genome-wide genetic diversity in over 11,000 domestic cats

In the largest DNA-based study of domestic cats to date, 11,036 individuals (10,419 pedigreed cats and 617 non-pedigreed cats) were genotyped via commercial panel testing elucidating the distribution and frequency of known disease, blood type, and physical trait associated genetic variants across cat breeds. This study provides allele frequencies for many disease-associated variants for the first time and provides updates on previously reported information with evidence suggesting that DNA testing has been effectively used to reduce disease associated variants within certain pedigreed cat populations over time. We identified 13 disease-associated variants in 47 breeds or breed types in which the variant had not previously been documented, highlighting the relevance of comprehensive genetic screening across breeds. Three disease-associated variants were discovered in non-pedigreed cats only. To investigate the causality of nine disease-associated variants in cats of different breed backgrounds our veterinarians conducted owner interviews, reviewed clinical records, and invited cats to have follow-up clinical examinations. Additionally, genetic variants determining blood types A, B and AB, which are relevant clinically and in cat breeding, were genotyped. Appearance-associated genetic variation in all cats is also discussed. Lastly, genome-wide SNP heterozygosity levels were calculated to obtain a comparable measure of the genetic diversity in different cat breeds. This study represents the first comprehensive exploration of informative Mendelian variants in felines by screening over 10,000 pedigreed cats. The results qualitatively contribute to the understanding of feline variant heritage and genetic diversity and demonstrate the clinical utility and importance of such information in supporting breeding programs and the research community. The work also highlights the crucial commitment of pedigreed cat breeders and registries in supporting the establishment of large genomic databases, that when combined with phenotype information can advance scientific understanding and provide insights that can be applied to improve the health and welfare of cats.

Domestic cats are one of the world’s most popular companion animals, of which pedigreed cats represent small unique subpopulations. Genetic research on pedigreed cats has facilitated discoveries of heritable conditions resulting in the availability of DNA testing for studying and managing inherited disorders and traits in specific cat breeds. We have explored an extensive study cohort of 11,036 domestic cat samples representing pedigreed cats of 90 breeds and breed types. This work provided insight into the heritage of feline disease and trait alleles. We gained knowledge on the most common and relevant genetic markers for inherited disorders and physical traits, and the genetic determinants of the clinically relevant AB blood group system. We also used a measure of genetic diversity to compare inbreeding levels within and between breeds. This information can help support sustainable breeding goals within the cat fancy. Direct-to-consumer genetic tests help to raise awareness of various inherited single gene conditions in cats and provide information that owners can share with their veterinarians. In due course, ventures of this type will enable the genetics of common complex feline disease to be deciphered, paving the way for precision healthcare with the potential to ultimately improve welfare for all cats.

Owner-Reported Pica in Domestic Cats Enrolled onto a Birth Cohort Study

Simple Summary

This study investigated the types of materials targeted by cats eating non-nutritive materials (‘pica’), at about 6, 12 and 18 months of age, as reported by owners. Pica was most common at about 6 months, as compared to the older age categories. Most cats targeted a single type of material, with plastics and other materials being chewed or eaten more commonly than wool or other fabrics. The factors associated with the occurrence of “chronic pica” (pica exhibited at all three timepoints) in cats were also investigated. Moving to a new house, renting rather than owning a home, and living in a household without a dog(s) were factors found to increase the odds of a cat displaying chronic pica.

Abstract

The prevalence and cooccurrence of pica towards different target materials were investigated using prospective data from three questionnaires completed by owners participating in a longitudinal study of UK pet cats. Pica towards one or more material types was reported in 42.9% (229/534), 32.0% (171/534), and 30.9% (165/534) of cats aged approximately 6, 12, and 18 months, respectively. At all timepoints, it was most common for only one material type to be targeted. Associations between potential explanatory variables and “chronic pica” (pica exhibited at all three timepoints) were also explored. Multivariable logistic regression revealed moving to a new house when the cat was aged approximately 6–12 months, renting rather than owning a home, and living in a household without a dog(s) when the cat was aged 2–4 months increased the odds of chronic pica occurrence. This study provides novel data from a cohort of UK pet cats and it is hoped this will increase the understanding of pica and provide direction for areas for future research.

Feline non-regenerative anemia: Diagnostic and treatment recommendations

PRACTICAL RELEVANCE

Non-regenerative anemia, or anemia with reticulocytopenia, is a daily diagnosis in feline practice.

CLINICAL CHALLENGES

The disease processes underlying non-regenerative anemia are many and diverse. A major diagnostic evaluation may be required to correctly diagnose and treat the underlying cause.

AUDIENCE

All veterinarians caring for cats will face the diagnostic and therapeutic challenge of non-regenerative anemia. Readers will benefit from the review of diagnostic testing and therapeutic options for non-regenerative anemia.

EVIDENCE BASE

This review summarizes the currently available literature informing diagnostic and treatment recommendations related to non-regenerative anemia. The evidence available to support the recommendations in this review is graded as low and includes predominantly expert opinion, case reports and cases series, on which the authors' interpretation/consensus is based.

Characterization of pica and chewing behaviors in privately owned cats: a case-control study

OBJECTIVES

The aim of this study was to characterize pica behavior in cats.

METHODS

Cat owners were recruited to participate in a questionnaire survey on pica behavior exhibited by their cats. Emphasis was put on the type of item ingested. Questions on early history and environment, as well as general health and gastrointestinal signs, were asked. Owners of healthy cats not showing pica were also recruited into a control group. Associations between variables and groups were statistically tested.

RESULTS

Pica was directed most commonly at shoelaces or threads, followed by plastic, fabric, other items, rubber, paper or cardboard and wood. Some cats ingested specific items but only chewed others. A significant positive association was found between sucking and ingesting fabric (P = 0.002). Ad libitum feeding was significantly lower in the pica group than the control group (P = 0.01). Prevalence of self-sucking behavior was significantly higher in the pica group than the control group (P = 0.001). Cats with pica vomited significantly more often than control cats (P = 0.01).

CONCLUSIONS AND RELEVANCE

Pica, the ingestion of inedible items, does not seem to be the consequence of a suboptimal environment or early weaning. Cats with pica were less commonly fed ad libitum than healthy cats. As frequently reported, pica and vomiting were related, but the causative association is not well established and thus warrants further investigation.

DNA mutations of the cat: the good, the bad and the ugly

PRACTICAL RELEVANCE

The health of the cat is a complex interaction between its environment (nurture) and its genetics (nature). Over 70 genetic mutations (variants) have been defined in the cat, many involving diseases, structural abnormalities and clinically relevant health concerns. As more of the cat's genome is deciphered, less commonly will the term 'idiopathic' be used regarding the diagnosis of diseases and unique health conditions. State-of-the-art health care will include DNA profiling of the individual cat, and perhaps its tumor, to establish the best treatment approaches. Genetic testing and eventually whole genome sequencing should become routine diagnostics for feline health care.

GLOBAL IMPORTANCE

Cat breeds have disseminated around the world. Thus, practitioners should be aware of the breeds common to their region and the mutations found in those regional populations. Specific random-bred populations can also have defined genetic characteristics and mutations.

AUDIENCE

This review of 'the good, the bad and the ugly' DNA variants provides the current state of knowledge for genetic testing and genetic health management for cats. It is aimed at feline and general practitioners wanting to update and review the basics of genetics, what tests are available for cats and sources for genetic testing. The tables are intended to be used as references in the clinic. Practitioners with a high proportion of cat breeder clientele will especially benefit from the review.

EVIDENCE BASE

The data presented is extracted from peer-reviewed publications pertaining to mutation identification, and relevant articles concerning the heritable trait and/or disease. The author also draws upon personal experience and expertise in feline genetics.

Real-time PCR genotyping assay for feline erythrocyte pyruvate kinase deficiency and mutant allele frequency in purebred cats in Japan

Erythrocyte pyruvate kinase (PK) deficiency is an inherited glycolytic erythroenzymopathy caused by mutations of the PKLR gene. A causative mutation of the feline PKLR gene was originally identified in Abyssinian and Somali cats in the U.S.A. In the present study, a TaqMan probe-based real-time PCR genotyping assay was developed and evaluated for rapid genotyping and large-scale screening for this mutation. Furthermore, a genotyping survey was carried out in a population of four popular purebred cats in Japan to determine the current mutant allele frequency. The assay clearly displayed all genotypes of feline PK deficiency, indicating its suitability for large-scale survey as well as diagnosis. The survey demonstrated that the mutant allele frequency in Abyssinian and Somali cats was high enough to warrant measures to control and prevent the disease. The mutant allele frequency was relatively low in Bengal and American Shorthair cats; however, the testing should still be carried out to prevent the spread of the disease. In addition, PK deficiency should always be considered in the differential diagnosis of anemia in purebred cats in Japan as well as worldwide.

Abnormal repetitive behaviors in dogs and cats: a guide for practitioners

Abnormal repetitive behaviors (ARBs) represent a diverse group of behaviors whose underlying mechanism is poorly understood. Their neurobiology likely involves several different neurotransmitter systems. These behaviors have been referred to as compulsive disorders, obsessive compulsive disorders and stereotypies. Underlying medical conditions and pain can often cause changes in behavior that are mistaken for ARBs. A complete medical work-up is always indicated prior to reaching a presumptive diagnosis. The frequency of ARBs can be reduced but not always eliminated with the use of selective serotonin reuptake inhibitors (SSRIs) or tricyclic antidepressants (TCAs) in conjunction with behavior modification and environmental enrichment.

Erythrocyte pyruvate kinase deficiency in three West Highland white terriers in Ireland and the UK

Erythrocyte pyruvate kinase (PK) deficiency is described for the first time in three apparently unrelated West Highland white terriers (WHWT) from Ireland and the UK. All three dogs were diagnosed with markedly regenerative but persistent anaemia and had been treated for presumed immune-mediated haemolytic anaemia (IMHA) before hereditary erythrocyte PK-deficiency was confirmed by breed-specific DNA mutation analysis. This hereditary erythroenzymopathy causes haemolytic anaemia and affects several canine breeds with varying degrees of severity. Although eventually causing osteosclerosis, haemosiderosis and death, PK-deficient dogs can adapt to their anaemia for many years.PK-deficiency should be considered in anaemic WHWTs worldwide particularly in dogs with haemolytic anaemia where evidence for an immune-mediated, infectious or toxic underlying cause is lacking.

A retrospective study of 180 anaemic cats: features, aetiologies and survival data

The study comprised 180 anaemic cats. Descriptive and survival data were obtained. Cats were classified by aetiology of anaemia development and degenerative, anomalous, metabolic, miscellaneous, neoplastic, infectious, inflammatory, immune-mediated, toxic, traumatic or vascular disease (DAMNITV) classification and anaemia severity. Sixty-four (35.6%) cats had mild [packed cell volume (PCV)/haematocrit (HCT) 20-24.9%], 58 (32.2%) moderate (14-19.9%), 23 (12.8%) severe (11-13.9%) and 35 (19.4%) very severe (<10.9%) anaemia. By aetiology of anaemia development, bone marrow (BM) abnormalities were more common (95, 52.8%) than haemorrhage (37, 20.6%) or haemolysis (19, 10.6%). By DAMNITV classification, infectious diseases were more common (39, 21.7%) than neoplasia (36, 20%), metabolic (21, 11.7%), trauma (15, 8.3%), miscellaneous (14, 7.8%), inflammatory (11, 6.1%), immune-mediated (11, 6.1%), anomalous (8, 4.4%), toxic (2, 1.1%) or vascular disease (1, 0.6%). BM abnormalities were significantly associated with more severe anaemia (P = 0.003). Most cats (112, 62.2%) survived to discharge whereas 55 (30.6%) were euthanased and 13 (7.2%) died. Survival to discharge was not associated with anaemia severity but was associated significantly with aetiology of anaemia development (P = 0.046), as cats with haemolysis were more likely to survive to discharge than cats with BM abnormalities. Survival to discharge was also associated significantly with DAMNITV classification (P = 0.010), with cats with neoplasia being less likely, and cats with immune-mediated disease more likely, to survive to discharge. Cox regression analysis found that survival was not associated with anaemia severity, but was associated with DAMNITV classification (P = 0.011) and age (P = 0.082), with cats with immune-mediated disease and younger cats more likely to survive.

Genetic testing in domestic cats

Varieties of genetic tests are currently available for the domestic cat that support veterinary health care, breed management, species identification, and forensic investigations. Approximately thirty-five genes contain over fifty mutations that cause feline health problems or alterations in the cat's appearance. Specific genes, such as sweet and drug receptors, have been knocked-out of Felidae during evolution and can be used along with mtDNA markers for species identification. Both STR and SNP panels differentiate cat race, breed, and individual identity, as well as gender-specific markers to determine sex of an individual. Cat genetic tests are common offerings for commercial laboratories, allowing both the veterinary clinician and the private owner to obtain DNA test results. This article will review the genetic tests for the domestic cat, and their various applications in different fields of science. Highlighted are genetic tests specific to the individual cat, which are a part of the cat's genome.

Erythrocyte pyruvate kinase deficiency mutation identified in multiple breeds of domestic cats

Background

Erythrocyte pyruvate kinase deficiency (PK deficiency) is an inherited hemolytic anemia that has been documented in the Abyssinian and Somali breeds as well as random bred domestic shorthair cats. The disease results from mutations in PKLR, the gene encoding the regulatory glycolytic enzyme pyruvate kinase (PK). Multiple isozymes are produced by tissue-specific differential processing of PKLR mRNA. Perturbation of PK decreases erythrocyte longevity resulting in anemia. Additional signs include: severe lethargy, weakness, weight loss, jaundice, and abdominal enlargement. In domestic cats, PK deficiency has an autosomal recessive mode of inheritance with high variability in onset and severity of clinical symptoms.

Results

Sequence analysis of PKLR revealed an intron 5 single nucleotide polymorphism (SNP) at position 304 concordant with the disease phenotype in Abyssinian and Somali cats. Located 53 nucleotides upstream of the exon 6 splice site, cats with this SNP produce liver and blood processed mRNA with a 13 bp deletion at the 3’ end of exon 5. The frame-shift mutation creates a stop codon at amino acid position 248 in exon 6. The frequency of the intronic SNP in 14,179 American and European cats representing 38 breeds, 76 western random bred cats and 111 cats of unknown breed is 6.31% and 9.35% when restricted to the 15 groups carrying the concordant SNP.

Conclusions

PK testing is recommended for Bengals, Egyptian Maus, La Perms, Maine Coon cats, Norwegian Forest cats, Savannahs, Siberians, and Singapuras, in addition to Abyssinians and Somalis as well an any new breeds using the afore mentioned breeds in out crossing or development programs.

Erythrocytic pyruvate kinase mutations causing hemolytic anemia, osteosclerosis, and secondary hemochromatosis in dogs

BACKGROUND

Erythrocytic pyruvate kinase (PK) deficiency, first documented in Basenjis, is the most common inherited erythroenzymopathy in dogs.

OBJECTIVES

To report 3 new breed-specific PK-LR gene mutations and a retrospective survey of PK mutations in as mall and selected group of Beagles and West Highland White Terriers (WHWT).

ANIMALS

Labrador Retrievers (2 siblings, 5 unrelated), Pugs (2 siblings, 1 unrelated), Beagles (39 anemic, 29 other),WHWTs (22 anemic, 226 nonanemic), Cairn Terrier (n = 1).

METHODS

Exons of the PK-LR gene were sequenced from genomic DNA of young dogs (<2 years) with persistent highly regenerative hemolytic anemia.

RESULTS

A nonsense mutation (c.799C>T) resulting in a premature stop codon was identified in anemic Labrador Retriever siblings that had osteosclerosis, high serum ferritin concentrations, and severe hepatic secondary hemochromatosis. Anemic Pug and Beagle revealed 2 different missense mutations (c.848T>C, c.994G>A, respectively) resulting in intolerable amino acid changes to protein structure and enzyme function. Breed-specific mutation tests were developed. Among the biased group of 248 WHWTs, 9% and 35% were homozygous (affected) and heterozygous, respectively, for the previously described mutation (mutant allele frequency 0.26). A PK-deficient Cairn Terrier had the same insertion mutation as the affected WHWTs. Of the selected group of 68 Beagles, 35% were PK-deficient and 3% were carriers (0.37).

CONCLUSIONS AND CLINICAL IMPORTANCE

Erythrocytic PK deficiency is caused by different mutations in different dog breeds and causes chronic severe hemolytic anemia, hemosiderosis, and secondary hemochromatosis because of chronic hemolysis and, an as yet unexplained osteosclerosis. The newly developed breed-specific mutation assays simplify the diagnosis of PK deficiency.

Feline genetics: clinical applications and genetic testing

DNA testing for domestic cat diseases and appearance traits is a rapidly growing asset for veterinary medicine. Approximately 33 genes contain 50 mutations that cause feline health problems or alterations in the cat's appearance. A variety of commercial laboratories can now perform cat genetic diagnostics, allowing both the veterinary clinician and the private owner to obtain DNA test results. DNA is easily obtained from a cat via a buccal swab with a standard cotton bud or cytological brush, allowing DNA samples to be easily sent to any laboratory in the world. The DNA test results identify carriers of the traits, predict the incidence of traits from breeding programs, and influence medical prognoses and treatments. An overall goal of identifying these genetic mutations is the correction of the defect via gene therapies and designer drug therapies. Thus, genetic testing is an effective preventative medicine and a potential ultimate cure. However, genetic diagnostic tests may still be novel for many veterinary practitioners and their application in the clinical setting needs to have the same scrutiny as any other diagnostic procedure. This article will review the genetic tests for the domestic cat, potential sources of error for genetic testing, and the pros and cons of DNA results in veterinary medicine. Highlighted are genetic tests specific to the individual cat, which are a part of the cat's internal genome.

Potential large animal models for gene therapy of human genetic diseases of immune and blood cell systems

Genetic mutations involving the cellular components of the hematopoietic system--red blood cells, white blood cells, and platelets--manifest clinically as anemia, infection, and bleeding. Although gene targeting has recapitulated many of these diseases in mice, these murine homologues are limited as translational models by their small size and brief life span as well as the fact that mutations induced by gene targeting do not always faithfully reflect the clinical manifestations of such mutations in humans. Many of these limitations can be overcome by identifying large animals with genetic diseases of the hematopoietic system corresponding to their human disease counterparts. In this article, we describe human diseases of the cellular components of the hematopoietic system that have counterparts in large animal species, in most cases carrying mutations in the same gene (CD18 in leukocyte adhesion deficiency) or genes in interacting proteins (DNA cross-link repair 1C protein and protein kinase, DNA-activated catalytic polypeptide in radiation-sensitive severe combined immunodeficiency). Furthermore, we describe the potential of these animal models to serve as disease-specific preclinical models for testing the efficacy and safety of clinical interventions such as hematopoietic stem cell transplantation or gene therapy before their use in humans with the corresponding disease.

Genetic control of resistance to human malaria

The term 'innate resistance' covers mechanisms of resistance that operate early in the course of infections, preceding adaptive immune responses which exert effects after several days. The first example of genetically controlled innate resistance to human malaria was the demonstration in 1954 that sickle-cell heterozygotes have less severe Plasmodium falciparum infections than do children with normal adult hemoglobin. This observation has been repeatedly confirmed, most recently by independent studies of genome-wide associations in severe falciparum malaria, which have identified the HBB locus as the major signal of association. Other abnormal hemoglobins, glucose-6-phosphate dehydrogenase deficiency and pyruvate kinase deficiency also confer some degree of resistance against falciparum malaria. A second early example of inherited innate resistance to malaria was the finding that nonexpression of the Duffy antigen/chemokine receptor (DARC) on erythrocytes confers resistance to P. vivax. However, this parasite can enter nonhuman primate red cells independently of DARC, and in some human populations P. vivax has been observed in persons lacking DARC. Hence DARC is not the only receptor for P. vivax, but it is likely to be a major one for human transmission. Innate resistance to malaria is rapidly reinforced by adaptive immune responses, both cell-mediated and humoral. Among the factors influencing the efficacy of adaptive immune responses to malaria is the MHC complex constitution of hosts. This differs among populations, presumably because of variations in the structure of parasite antigens recognized by the immune systems of hosts.

Erythrocytic pyruvate kinase deficiency and AB blood types in Australian Abyssinian and Somali cats

OBJECTIVE

To determine the frequency of the mutant pyruvate kinase (PK) allele, haematological parameters and AB blood types of Abyssinian and Somali cats in Australia.

DESIGN

Complete blood cell and reticulocyte counts, DNA PK mutation testing and blood typing were performed in all cats.

RESULTS

A total of 60 cats (36 Abyssinians, 24 Somalis) were included (37 females, 23 males). For the mutant PK allele, three female Somalis were homozygous (affected, 5%), 17 cats were heterozygous (carrier, 28%) and 40 cats tested negative (normal, 67%). Pedigree analysis revealed common ancestry of affected and many carrier cats. Of affected cats, two had regenerative anaemias and all had reticulocytosis (range 64-390 x 10(9)/L; P < 0.001 compared with normal or carrier cats). The only consistent historical sign was lethargy. One affected cat was euthanased 18 months after testing, because of anaemia, neutropenia, anorexia and weight loss. The mutant allele frequency was 0.19 overall (0.29 in Somalis, 0.13 in Abyssinians). All cats had blood type A. The commercial blood typing card method incorrectly identified 12 cats as having type AB blood.

CONCLUSIONS

The frequency of the mutant PK allele is high in Australia. Screening for PK deficiency is indicated before mating and in individual cats of these breeds, even in the absence of anaemia and especially when there is reticulocytosis. Although all cats in the present study had blood type A, blood type B is common in these breeds worldwide. Retyping of any AB typed cats by a laboratory technique is recommended.