Precision medicine in cats:novel niemann-pick type C1 diagnosed by whole-genome sequencing

State-of-the-art health care includes genome sequencing of the patient to identify genetic variants that contribute to either the cause of their malady or variants that can be targeted to improve treatment. The goal was to introduce state-of-the-art health care to cats using genomics and a precision medicine approach. To test the feasibility of a precision medicine approach in domestic cats, a single cat that presented to the University of Missouri, Veterinary Health Center with an undiagnosed neurologic disease was whole-genome sequenced. The DNA variants from the cat were compared to the DNA variant database produced by the 99 Lives Cat Genome Sequencing Consortium. Approximately 25× genomic coverage was produced for the cat. A predicted p.H441P missense mutation was identified in NPC1, the gene causing Niemann-Pick type C1 on cat chromosome D3.47456793 caused by an adenine-to-cytosine transversion, c.1322A>C. The cat was homozygous for the variant. The variant was not identified in any other 73 domestic and 9 wild felids in the sequence database or 190 additionally genotyped cats of various breeds. The successful effort suggested precision medicine is feasible for cats and other undiagnosed cats may benefit from a genomic analysis approach. The 99 Lives DNA variant database was sufficient but would benefit from additional cat sequences. Other cats with the mutation may be identified and could be introduced as a new biomedical model for NPC1. A genetic test could eliminate the disease variant from the population

A deletion in GDF7 is associated with a heritable forebrain commissural malformation concurrent with ventriculomegaly and interhemispheric cysts in cats

Publisher Copyright: © 2020 by the authors.An inherited neurologic syndrome in a family of mixed-breed Oriental cats has been characterized as forebrain commissural malformation, concurrent with ventriculomegaly and interhemispheric cysts. However, the genetic basis for this autosomal recessive syndrome in cats is unknown. Forty-three cats were genotyped on the Illumina Infinium Feline 63K iSelect DNA Array and used for analyses. Genome-wide association studies, including a sib-transmission disequilibrium test and a case-control association analysis, and homozygosity mapping, identified a critical region on cat chromosome A3. Short-read whole genome sequencing was completed for a cat trio segregating with the syndrome. A homozygous 7 bp deletion in growth differentiation factor 7 (GDF7) (c.221_227delGCCGCGC [p.Arg74Profs]) was identified in affected cats, by comparison to the 99 Lives Cat variant dataset, validated using Sanger sequencing and genotyped by fragment analyses. This variant was not identified in 192 unaffected cats in the 99 Lives dataset. The variant segregated concordantly in an extended pedigree. In mice, GDF7 mRNA is expressed within the roof plate when commissural axons initiate ventrally-directed growth. This finding emphasized the importance of GDF7 in the neurodevelopmental process in the mammalian brain. A genetic test can be developed for use by cat breeders to eradicate this variant.Peer reviewe

Werewolf, there wolf : Variants in hairless associated with hypotrichia and roaning in the lykoi cat breed

Publisher Copyright: © 2020 by the authors. Licensee MDPI, Basel, Switzerland.A variety of cat breeds have been developed via novelty selection on aesthetic, dermatological traits, such as coat colors and fur types. A recently developed breed, the lykoi (a.k.a. werewolf cat), was bred from cats with a sparse hair coat with roaning, implying full color and all white hairs. The lykoi phenotype is a form of hypotrichia, presenting as a significant reduction in the average numbers of follicles per hair follicle group as compared to domestic shorthair cats, a mild to severe perifollicular to mural lymphocytic infiltration in 77% of observed hair follicle groups, and the follicles are often miniaturized, dilated, and dysplastic. Whole genome sequencing was conducted on a single lykoi cat that was a cross between two independently ascertained lineages. Comparison to the 99 Lives dataset of 194 non‐lykoi cats suggested two variants in the cat homolog for Hairless (HR) (HR lysine demethylase and nuclear receptor corepressor) as candidate causal gene variants. The lykoi cat was a compound heterozygote for two loss of function variants in HR, an exon 3 c.1255_1256dupGT (chrB1:36040783), which should produce a stop codon at amino acid 420 (p.Gln420Serfs*100) and, an exon 18 c.3389insGACA (chrB1:36051555), which should produce a stop codon at amino acid position 1130 (p.Ser1130Argfs*29). Ascertainment of 14 additional cats from founder lineages from Canada, France and different areas of the USA identified four additional loss of function HR variants likely causing the highly similar phenotypic hair coat across the diverse cats. The novel variants in HR for cat hypotrichia can now be established between minor differences in the phenotypic presentations.Peer reviewe

Investigations of a novel lymphoproliferative disease in British shorthair kittens : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand

In 2009, three sibling British shorthair (BSH) kittens presented with lymphoproliferative disease (LPD) causing massive enlargement of multiple lymph nodes, a presentation that suggested an inherited predisposition to the disease. While aspects of the disease presentation suggested a diagnosis of lymphoma, other features were inconsistent with lymphoid neoplasia. In particular, the consistently young age of affected kittens, the pattern of disease affecting multiple littermates, and the presence of such marked generalised lymphadenopathy, were all atypical for feline lymphoma. This unusual constellation of clinical and pathologic features in affected BSH kittens had not been previously reported in cats but had several similarities to the human disease autoimmune lymphoproliferative syndrome (ALPS), a rare inherited disorder causing persistent LPD, increased numbers of CD3+/CD4-/CD8- double negative T-cells (DNT cells) and variable manifestations of autoimmunity. The majority of human ALPS patients have inherited Fas gene mutations causing defective T-cell apoptosis, although in some patients the cause of disease is still unknown. The thesis further describes and investigates this novel LPD in BSH kittens. The results of breeding trials, pedigree information and reviews of historical records support an inherited basis for the disease, most likely with either a simple autosomal recessive or modified autosomal dominant mode of inheritance. The typical clinical presentation is the development of a massive multicentric lymphadenopathy, splenomegaly and probable haemolytic anaemia in previously healthy kittens between 5 to 7 weeks of age. Microscopic pathology and immunophenotypic studies are suggestive of multicentric T-cell lymphoma affecting the lymph nodes, spleen, and sometimes other organs, but clonality assays confirm a non-clonal and likely non-neoplastic T-cell LPD. Where tested, the proliferating T-cells show a DNT cell immunophenotype and reduced apoptosis on in situ methods. Qualitative Fas gene abnormalities were not identified in affected kittens using reverse-transcriptase polymerase chain reaction techniques. The studies described in the thesis therefore confirm a novel and likely non-neoplastic T-cell LPD in BSH kittens with a probable inherited basis. Results support defective T-cell apoptosis as a possible factor in disease development, although causative genetic abnormalities have not yet been identified. The disease in kittens has several similarities to ALPS in people, although the apparent absence of Fas gene abnormalities in affected kittens may limit the use of the feline disease as a disease model for ALPS

Immunostaining for p53 and p16^CDKN2A Protein Is Not Predictive of Prognosis for Dogs with Malignant Mammary Gland Neoplasms

Mammary gland tumors (MGTs) are common in dogs and show a variable clinical behavior that is difficult to predict. Currently, few immunohistochemical markers have been established to predict the prognosis of a canine MGT. However, p53 immunostaining has been variably reported to be prognostic for canine MGTs. Additionally, while p16CDK2NA protein (p16) immunostaining has been found to be prognostic for human breast cancers, this marker has never been evaluated as a prognostic marker for canine neoplasms. In the present study, the prognostic utility of p53 and p16 was evaluated in 35 canine malignant MGTs. It was observed that 19 (54%) dogs died due to their MGTs with an overall mean survival time (MST) of 882 days. Seven MGTs showed p53 immunostaining, but this was not significantly associated with death (4 of 7 vs. 15 of 28; p = 0.6) or MST (670 vs. 934 days; p = 0.57). Five dogs had MGTs with no p16 immunostaining, 28 MGTs had intermediate p16 immunostaining, and two MGTs had increased p16 immunostaining. Neither death due to MGT (4 of 5, 14 of 28, or 1 of 2; p = 0.28) nor MST (683, 927, and 307 days; p = 0.31) were significantly associated with p16 immunostaining. Interestingly, p53 immunostaining was significantly associated with an increase or loss of p16 immunostaining. This is the first time that p16 has been evaluated as a prognostic marker for canine neoplasms. While these results suggest that a proportion of canine MGTs develop by cellular mechanisms that alter both p53 and p16 expression, there was no evidence that defects in p53 or p16 alter the behavior of a MGT. Neither p53 nor p16 was found to significantly predict prognosis, although this could reflect the limited number of MGTs included in the study

Papillomavirus DNA is not Amplifiable from Bladder, Lung, or Mammary Gland Cancers in Dogs or Cats

Papillomaviruses (PVs) cause around 5% of all human cancers, including most cervical cancers and around a quarter of all oral cancers. Additionally, some studies have suggested that PVs could cause a proportion of human lung, breast, and bladder cancers. As PVs have been associated with skin cancer in cats and, more rarely, dogs, it was hypothesized that these viruses could also contribute to epithelial cancers of the lung, mammary gland, and bladder of dogs and cats. Formalin-fixed paraffin-embedded samples of 47 canine and 25 feline cancers were examined histologically for evidence of PV infection. Additionally, three sets of consensus PCR primers were used to amplify PV DNA from the samples. No histological evidence of PV infection was visible in any of the cancers. DNA from a bovine PV type was amplified from one sample, while two different samples were found to contain human PV DNA. However, these were considered to be contaminants, and no canine or feline PV types were amplified from any of the cancers. These results suggest that PVs do not frequently infect the lung, mammary gland, or bladder of dogs and cats and therefore are unlikely to be significant factors in the development of cancers in these tissues

Clinicopathological Diversity of Canine Mammary Gland Tumors in Sri Lanka: A One-Year Survey on Cases Presented to Two Veterinary Practices

Mammary gland tumors (MGTs) are one of the most common neoplasms among dogs in Sri Lanka. However, the clinicopathological diversity of MGTs in Sri Lanka is largely unknown, impeding accurate diagnosis and effective treatment of the disease. The present study investigated the clinicopathological features of MGTs in 74 dogs presented to two veterinary practices in Sri Lanka treated surgically, over a one-year period. Information regarding the patient signalment, clinical presentation, and reproductive history were collected, and each neoplasm was examined histologically. Forty-one (54.4%) dogs were primarily presented for mammary neoplasia, while a MGT was an incidental finding in 33 (44.6%) dogs. The majority of tumors were histologically malignant (n = 65, 87.8%), and 18 malignant tumor sub-types were identified. A significantly higher proportion of malignant tumors were large (>3 cm diameter) and observed in inguinal mammary glands. Nulliparous (n = 42, 55.3%) dogs predominated in the group, and the mean age of MGT diagnosis was 8.0 ± 2.41 years. The present study identified tumor location and size to be predictive of malignancy. A high histological diversity of MGTs was observed. Overall, the present findings emphasize the necessity of improving awareness of MGTs among Sri Lankan clinicians as well as dog owners

Relationships between cytology, bacteriology and vaginal discharge scores and reproductive performance in dairy cattle

The objective was to compare three diagnostic approaches for intrauterine infection and inflammation: scoring of vaginal contents; quantification of percentage of nucleated cells that were polymorphonuclear leukocytes (PMN) following endometrial cytology; and intra-uterine bacteriology. Dairy cows (n = 303) were examined twice, Days 28 (D28) and 42 (D42), where Day 0 = day of calving. Associations between gross vaginal inflammation scores, uterine cytology, and bacteriology, and subsequent reproductive performance were examined using multivariable models. There was fair agreement at D28 (Kappa = 0.29), but only slight agreement at D42 (Kappa < 0.15), between PMN% and gross vaginal inflammation score. Cows were categorized as having PMN% in the highest quartile (H), or not (L), at both D28 and D42; therefore, cows were categorized as PMNLL, PMNLH, PMNHL, or PMNHH. Cows in the highest PMN% quartile at both time periods were slower to conceive (P < 0.001) than those in all other quartiles (mean ± SEM 32.2 ± 2.3, 37.0 ± 5.3, 40.8 ± 4.1, and 55.3 ± 7.3 d from start of breeding to conception for PMNLL, PMNLH, PMNHL, and PMNHH PMN% cows, respectively). Milk yield was greater (P = 0.001) in cows in the lower quartiles for PMN% at D28 and D42 (i.e., PMNLL) than those in the PMNHH and PMNHL categories, with PMNLH intermediate (P = 0.001). We concluded that PMN% was a better predictor of reproductive performance than either intra-uterine bacteriology or gross vaginal inflammation score. Cows in the highest quartile for PMN% at both D28 and D42 had lower pregnancy rates, took longer to conceive, and had a lower milk yield than those in the lower PMN% categories.</p

Videofluoroscopy, CT angiography, and ultrasonography of congenital esophageal stenosis in a Labrador retriever

A 7‐week‐old Labrador retriever presented for further investigation into acute onset regurgitation, following weaning from liquid to solid food. A videofluoroscopic swallow study demonstrated a severe, focal esophageal dilation in the mid‐cervical region, with marked luminal narrowing distally. Computed tomography with angiography revealed esophageal stenosis, extending from C4–T2, secondary to circumferential esophageal wall thickening. With the concern for development of secondary aspiration pneumonia, the owners elected to euthanize the dog and consented to postmortem examination. A diagnosis of segmental, cervical esophageal muscular hypertrophy was made on necropsy, consistent with the fibromuscular thickening type of congenital esophageal stenosis reported in humans