Publications by authors named "Letko A"

Article Synopsis
  • Bovine spastic syndrome (SS) is an inherited neuromuscular disorder affecting Holstein cattle, causing muscle spasms starting around 5 years of age.
  • Whole-genome sequencing (WGS) was used in this study to explore the genetic causes of SS, revealing a likely pathogenic variant in one case and several potentially harmful mutations in others.
  • The findings indicate that SS has a complex genetic basis, involving multiple candidate genes, rather than a single genetic cause.
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  • Hereditary sensory and autonomic neuropathies (HSAN) are genetic disorders affecting the peripheral nervous system, with at least 16 known genetic loci in humans, while similar conditions like acral mutilation syndrome (AMS) have been noted in dogs, especially impacting their quality of life.
  • A study focused on a purebred German Spitz showed early-onset HSAN/AMS, leading to severe self-mutilation due to loss of pain sensation, and whole-genome sequencing identified a variant in the RETREG1 gene as the likely cause.
  • This variant impairs neuron function and confirms its role in the recessive form of HSAN/AMS for the breed, highlighting
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Background: Chiari malformation type II (CMII) was originally reported in humans as a rare disorder characterized by the downward herniation of the hindbrain and towering cerebellum. The congenital brain malformation is usually accompanied by spina bifida, a congenital spinal anomaly resulting from incomplete closure of the dorsal aspect of the spinal neural tube, and occasionally by other lesions. A similar disorder has been reported in several animal species, including cattle, particularly as a congenital syndrome.

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  • This study focused on the Dominant Blue Eyes (DBE) trait in Maine Coon cats, which is associated with hearing impairment and white spotting patterns; it examined 58 cats from two different bloodlines.
  • A brainstem auditory evoked response test indicated all 8 DBE cats tested had reduced or absent responses to sounds, suggesting a link between blue eyes and deafness in these animals.
  • The researchers identified a specific mutation in the PAX3 gene as a likely cause of the DBE trait and related health conditions, proposing it be designated as the DBERE (Rociri Elvis Dominant Blue Eyes) allele in domestic cats.
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Schistosoma reflexum (SR) is a lethal congenital syndrome characterized by U-shaped dorsal retroflexion of the spine and exposure of abdominal viscera. SR is usually associated with severe dystocia. The syndrome is thought to be inherited as a Mendelian trait.

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The difference in fleece type is the distinguishing trait between the two types of alpacas (Vicugna pacos), Huacaya and Suri. The Suri fleece type has been found to be inherited dominantly over the Huacaya type, resulting in offspring with the Suri phenotype. The aim of our study was to map genomic regions associated with the two different fleece types.

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Microcephaly is a rare neurodevelopmental disorder characterized by reduced skull circumference and brain volume that occurs sporadically in farm animals. We investigated an early-onset neurodegenerative disorder observed in seven lambs of purebred Kerry Hill sheep. Clinical signs included inability to stand or severe ataxia, convulsions, and early death.

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Epidermolysis bullosa (EB), characterized by defective adhesion of the epidermis to the dermis, is a heterogeneous disease with many subtypes in human patients and domestic animals. We investigated two unrelated cats with recurring erosions and ulcers on ear pinnae, oral mucosa, and paw pads that were suggestive of EB. Histopathology confirmed the diagnosis of EB in both cats.

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An 8-month-old female Lagotto Romagnolo dog was presented for a 1-month history of an initial severe reluctance to move, rapidly progressing to a marked stiff gait and progressive muscular weakness and evolving to tetraparesis, which persuaded the owner to request euthanasia. A primary muscle pathology was supported by necropsy and histopathological findings. Macroscopically, the muscles were moderately atrophic, except for the diaphragm and the neck muscles, which were markedly thickened.

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In North Country Cheviot lambs with early-onset progressive ataxia and motor neuron degeneration, whole-genome sequencing identified a homozygous loss-of-function variant in the ovine transmembrane and coiled-coil domains (TMCO6) gene. The familial recessive form of motor neuron disease in sheep is due to a pathogenic 4 bp deletion leading to a 50% protein truncation that is assumed to result in the absence of a functional TMCO6. This uncharacterised protein is proposed to interact with ubiquilin 1 which is associated with Alzheimer's disease, whereas sporadic forms of amyotrophic lateral sclerosis are caused by variants in UBQLN2.

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  • Bernese mountain dogs originated in early 1900s Switzerland as farm dogs used for tasks like pulling carts and guarding cattle, but now they serve as family companions.
  • A study using whole-genome sequencing analyzed 33 Bernese mountain dogs from France, Sweden, Switzerland, and the U.S., revealing high inbreeding levels and limited genetic clustering between European and U.S. dogs, indicating cross-breeding.
  • The analysis found associations between certain genetic variants and diseases prevalent in the breed, particularly those related to immune functions, pointing to increased health issues likely caused by high inbreeding over the past 30 years.
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Organoid cultures could constitute a valuable in vitro model to explore new treatments for canine (c) medullary thyroid carcinoma (MTC). The study's objectives were to establish and characterize 3D organoid cultures of cMTC using histology and immunohistochemistry (IHC) and to evaluate the effect of antitumor drugs on organoids' viability. Five cMTC tissue samples were used to develop organoid cultures of which one organoid line, named cMTC N°2, could be passaged for an extended period.

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Mammary tumors in dogs hold great potential as naturally occurring breast cancer models in translational oncology, as they share the same environmental risk factors, key histological features, hormone receptor expression patterns, prognostic factors, and genetic characteristics as their human counterparts. We aimed to develop in vitro tools that allow functional analysis of canine mammary tumors (CMT), as we have a poor understanding of the underlying biology that drives the growth of these heterogeneous tumors. We established the long-term culture of 24 organoid lines from 16 dogs, including organoids derived from normal mammary epithelium or benign lesions.

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  • Dogs, particularly large breeds like the Leonberger, are valuable models for studying osteosarcoma (OSA), a common bone cancer that closely resembles the form found in humans.
  • A genome-wide analysis of 273 Leonberger cases revealed significant genetic associations on chromosome 11, reinforcing previous studies in other high-risk breeds like greyhounds.
  • The study determined a heritability of 20.6% for OSA, identifying 2563 SNPs that influence cancer risk, highlighting the importance of genetic factors in OSA predisposition in dogs.
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The aim of this study was to characterize the phenotype and to identify the genetic etiology of a syndromic form of ichthyosis congenita (IC) observed in Italian Chianina cattle and to estimate the prevalence of the deleterious allele in the population. Sporadic occurrence of different forms of ichthyosis including IC have been previously reported in cattle. However, so far, no causative genetic variant has been found for bovine IC.

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Distinctive colour patterns in dogs are an integral component of canine diversity. Colour pattern differences are thought to have arisen from mutation and artificial selection during and after domestication from wolves but important gaps remain in understanding how these patterns evolved and are genetically controlled. In other mammals, variation at the ASIP gene controls both the temporal and spatial distribution of yellow and black pigments.

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Cystic hygroma is a malformation of the lymphatic and vascular system and is recognized as a benign congenital tumor that affects humans and animals in the perinatal period. This congeni-tal disorder is rarely described in animals, and until today, cystic hygroma in pigs has not been described in the literature. In a purebred Piètrain litter with twelve live-born piglets, cystic hy-groma was noticed on the rump of two male pigs within the first week of life.

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Laryngeal paralysis associated with a generalized polyneuropathy (LPPN) most commonly exists in geriatric dogs from a variety of large and giant breeds. The purpose of this study was to discover the underlying genetic and molecular mechanisms in a younger-onset form of this neurodegenerative disease seen in two closely related giant dog breeds, the Leonberger and Saint Bernard. Neuropathology of an affected dog from each breed showed variable nerve fiber loss and scattered inappropriately thin myelinated fibers.

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Sporadic occurrences of neurodegenerative disorders including neuroaxonal dystrophy (NAD) have been previously reported in sheep. However, so far no causative genetic variant has been found for ovine NAD. The aim of this study was to characterize the phenotype and the genetic aetiology of an early-onset neurodegenerative disorder observed in several lambs of purebred Swaledale sheep, a native English breed.

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Classical Ehlers-Danlos syndrome (cEDS) is a heritable connective tissue disorder characterized by variable degrees of skin hyperextensibility and fragility, atrophic scarring, and generalized joint hypermobility. The purpose of this study was to characterize the clinicopathological phenotype of a cEDS-affected Holstein calf and to identify the causative genetic variant associated with the disorder by whole-genome sequencing (WGS). A 3-day-old female Holstein calf was referred because of easily induced skin detachment and hyperextensibility in the neck.

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Sporadic occurrence of juvenile-onset necrotizing encephalopathy (SNE) has been previously reported in Yorkshire terriers. However, so far, no causative genetic variant has been found for this breed-specific form of suspected mitochondrial encephalomyopathy. Affected dogs showed gait abnormalities, central visual defects, and/or seizures.

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Article Synopsis
  • The Leonberger breed, established in the 1850s, has around 30,000 dogs today but suffers from genetic diversity issues that lead to high rates of neurodegenerative disorders and cancer.
  • Analysis of pedigree records and genomic data indicates significant inbreeding with an average inbreeding coefficient of 0.29 and a decline in lifespan from 9.4 years in 1989 to 7.7 years in 2004.
  • Although the study identified possible genetic variants linked to health issues, no definitive causal genetic indicators were found, suggesting that other factors may contribute to the breed's health problems.
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