Imerslund-Grasbeck syndrome in a cross-breed dog.

Imerslund-Gräsbeck syndrome is an autosomal recessive disease reported only in certain pure-breed dogs. An 18-month-old, male neutered beagle cross-breed was presented for evaluation of severe lethargy, progressive weakness and anorexia. Main clinicopathological findings included low body condition score (2.5/9), severe muscle atrophy, several neurological abnormalities, mild normochromic, normocytic, non-regenerative anaemia, severe hypocobalaminemia and mild proteinuria. Extensive diagnostic tests ruled out most of differential diagnoses for the aforementioned clinicopathological abnormalities and genetic evaluation showed that the dog was heterozygous for two previously described mutations affecting the CUBN gene, the beagle and the border collie variants. The dog showed an excellent clinical response to oral cobalamin supplementation with no relapse after 4 months. In conclusion, this case creates awareness that Imerslund-Gräsbeck syndrome should be considered even in mixed-breed dogs with compatible clinical signs and that two different pathogenic CUBN mutations in compound heterozygosity can lead to a typical Imerslund-Gräsbeck syndrome phenotype.

A large deletion on CFA28 omitting ACSL5 gene is associated with intestinal lipid malabsorption in the Australian Kelpie dog breed.

Inborn errors of metabolism are genetic conditions that can disrupt intermediary metabolic pathways and cause defective absorption and metabolism of dietary nutrients. In an Australian Kelpie breeding population, 17 puppies presented with intestinal lipid malabsorption. Juvenile dogs exhibited stunted postnatal growth, steatorrhea, abdominal distension and a wiry coat. Using genome-wide association analysis, an associated locus on CFA28 (Praw = 2.87E-06) was discovered and validated in a closely related population (Praw = 1.75E-45). A 103.3 kb deletion NC_006610.3CFA28:g.23380074_23483377del, containing genes Acyl-CoA Synthetase Long Chain Family Member 5 (ACSL5) and Zinc Finger DHHC-Type Containing 6 (ZDHHC6), was characterised using whole transcriptomic data. Whole transcriptomic sequencing revealed no expression of ACSL5 and disrupted splicing of ZDHHC6 in jejunal tissue of affected Kelpies. The ACSL5 gene plays a key role in long chain fatty acid absorption, a phenotype similar to that of our affected Kelpies has been observed in a knockout mouse model. A PCR-based diagnostic test was developed and confirmed fully penetrant autosomal recessive mode of inheritance. We conclude the structural variant causing a deletion of the ACSL5 gene is the most likely cause for intestinal lipid malabsorption in the Australian Kelpie.

Daily oral cyanocobalamin supplementation in Beagles with hereditary cobalamin malabsorption (Imerslund-Gräsbeck syndrome) maintains normal clinical and cellular cobalamin status.

BACKGROUND: Efficacy of PO cobalamin (Cbl) supplementation in dogs with hereditary Cbl malabsorption (Imerslund-Gräsbeck syndrome, IGS) is unknown. OBJECTIVES: To evaluate PO Cbl supplementation in Beagles with IGS previously treated parenterally. We hypothesized that 1 mg cyano-Cbl daily PO would maintain clinical and metabolic remission. ANIMALS: Three client-owned Beagles with IGS and 48 healthy control dogs. METHODS: Prospective study. Daily PO cyanocobalamin (cyano-Cbl; 1 mg) supplementation was monitored for 13 (2 dogs) and 8 months (1 dog). Health status was assessed by owner observations. Methylmalonic acid (MMA)-to-creatinine concentrations were measured using an ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-TMS) method on urine samples collected monthly. Concurrent measurements of serum MMA concentration (n = 7; UPLC-TMS) were available for 1 dog. RESULTS: All dogs remained in excellent health during PO supplementation. Urine MMA remained consistently low in 2 dogs (median, 2.5 mmol/mol creatinine; range, 1.2-9; healthy dogs [n = 30], median, 2.9 mmol/mol creatinine; range, 1.3-76.5). Urine MMA ranged from 38.9-84.9 mmol/mol creatinine during the first 6 months in 1 dog already known to excrete comparable amounts when supplemented parenterally. Brief antibiotic treatment for an unrelated condition after 6 months resulted in low urine MMA (median, 2.8 mmol/mol creatinine; range, 1.9-4.8) for the next 7 months. All concurrent serum MMA concentrations (median, 651 nmol/L; range, 399-919) before and after month 6 were within the established reference interval (393-1476 nmol/L; n = 48). CONCLUSIONS AND CLINICAL IMPORTANCE: One milligram of cyano-Cbl daily PO appears efficacious for maintaining normal clinical status and normal cellular markers of Cbl metabolism in Beagles with IGS.

The intestinal virome of malabsorption syndrome-affected and unaffected broilers through shotgun metagenomics.

Malabsorption syndrome (MAS) is an economically important disease of young, commercially reared broilers, characterized by growth retardation, defective feather development and diarrheic faeces. Several viruses have been tentatively associated to such syndrome. Here, in order to examine potential associations between enteric viruses and MAS, the faecal viromes of 70 stool samples collected from diseased (n = 35) and healthy (n = 35) chickens from seven flocks were characterized and compared. Following high-throughput sequencing, a total of 8,347,319 paired end reads, with an average of 231 nt, were generated. Through analysis of de novo assembled contigs, 144 contigs > 1000 nt were identified with hits to eukaryotic viral sequences, as determined by GenBank database. A number of known and unknown representatives of Adenoviridae, Anelloviridae, Astroviridae, Caliciviridae, Circoviridae, Parvoviridae, Picobirnaviridae, Picornaviridae and Reoviridae, as well as novel uncharacterized CRESS-DNA viruses, were identified. However, the distribution of sequence reads of viral genomes identified in diseased or healthy birds revealed no statistically significant differences. These findings indicate no association between the occurrence of MAS and enteric viruses. The viral genomes reported in the present study, including a variety of novel viruses, seem part of the normal intestinal microbiota of chickens.

Inherited selective cobalamin malabsorption in Komondor dogs associated with a CUBN splice site variant.

BACKGROUND: Three Komondor dogs in a small family and 3 sporadic cases exhibited a constellation of signs that included juvenile-onset of failure-to-thrive, inappetence, vomiting and/or diarrhea, and weakness. In each we documented dyshematopoiesis, increased anion gap, methylmalonic acidemia/-uria, and serum cobalamin deficiency. Urine protein electrophoresis demonstrated excretion of cubam ligands. All clinical signs and metabolic abnormalities, except proteinuria, were reversed by regular parenteral cobalamin administration. The pattern of occurrence and findings in the disorder suggested an autosomal recessive inheritance of cobalamin malabsorption with proteinuria, a condition in humans called Imerslund-Gräsbeck syndrome. The purpose of this study was to determine the molecular cause of this disorder in Komondors. RESULTS: Whole genome sequencing of two affected Komondor dogs of unknown relatedness and one parent and a clinically-normal littermate of an affected dog revealed a pathogenic single-base change in the CUBN intron 55 splice donor consensus sequence (NM_001003148.1: c.8746 + 1G > A) that was homozygous in affected dogs and heterozygous in the unaffected parents. Alleles of the variant co-segregated with alleles of the disease locus in the entire family and all more distantly-related sporadic cases. A population study using a simple allele-specific DNA test indicated mutant allele frequencies of 8.3 and 4.5% among North American and Hungarian Komondors, respectively. CONCLUSIONS: DNA testing can be used diagnostically in Komondors when clinical signs are suggestive of cobalamin deficiency or to inform Komondor breeders prospectively and prevent occurrence of future affected dogs. This represents the third cubilin variant causing inherited selective cobalamin malabsorption in a large animal ortholog of human Imerslund-Gräsbeck syndrome.

Loss of HAI-2 in mice with decreased prostasin activity leads to an early-onset intestinal failure resembling congenital tufting enteropathy.

Prostasin (CAP1/PRSS8) is a glycosylphosphatidylinositol (GPI)-anchored serine protease that is essential for epithelial development and overall survival in mice. Prostasin is regulated primarily by the transmembrane serine protease inhibitor, hepatocyte growth factor activator inhibitor (HAI)-2, and loss of HAI-2 function leads to early embryonic lethality in mice due to an unregulated prostasin activity. We have recently reported that critical in vivo functions of prostasin can be performed by proteolytically-inactive or zymogen-locked variants of the protease. Here we show that the zymogen form of prostasin does not bind to HAI-2 and, as a result, loss of HAI-2 does not affect prenatal development and survival of mice expressing only zymogen-locked variant of prostasin (Prss8 R44Q). Indeed, HAI-2-deficient mice homozygous for R44Q mutation (Spint2-/-;Prss8R44Q/R44Q) are born in the expected numbers and do not exhibit any obvious developmental abnormality at birth. However, postnatal growth in these mice is severely impaired and they all die within 4 to 7 days after birth due to a critical failure in the development of small and large intestines, characterized by a widespread villous atrophy, tufted villi, near-complete loss of mucin-producing goblet cells, loss of colonic crypt structure, and bleeding into the intestinal lumen. Intestines of Spint2-/-;Prss8R44Q/R44Q mice showed altered expression of epithelial junctional proteins, including reduced levels of EpCAM, E-cadherin, occludin, claudin-1 and -7, as well as an increased level of claudin-4, indicating that the loss of HAI-2 compromises intestinal epithelial barrier function. Our data indicate that the loss of HAI-2 in Prss8R44Q/R44Q mice leads to development of progressive intestinal failure that at both histological and molecular level bears a striking resemblance to human congenital tufting enteropathy, and may provide important clues for understanding and treating this debilitating human disease.

Prospective long-term evaluation of parenteral hydroxocobalamin supplementation in juvenile beagles with selective intestinal cobalamin malabsorption (Imerslund-Gräsbeck syndrome).

BACKGROUND: Prospective studies on maintenance treatment for Beagles with hereditary selective cobalamin (Cbl) malabsorption (Imerslund-Gräsbeck syndrome, IGS) are lacking. In our experience, measurement of methylmalonic acid (MMA), a Cbl-dependent metabolite, seems more helpful to monitor Cbl status as compared with serum Cbl concentrations. OBJECTIVES: To evaluate a standardized Cbl supplementation scheme in Beagles with IGS. We hypothesized that a single parenteral dose of 1 mg hydroxocobalamin (OH-Cbl) would maintain clinical and metabolic remission for up to 2 months. ANIMALS: Six client-owned juvenile Beagles with genetically confirmed IGS and 28 healthy control dogs. METHODS: Prospective study. Monthly IM OH-Cbl (1 mg) supplementation was done over a median of 9 months (range, 6-13) in 6 dogs, followed by bimonthly (every 2 months) injections in 5 dogs over a median of 6 months (range, 3-10). Health status was assessed by routine clinical examinations at injection time points and owner observations. Voided urine samples were collected immediately before OH-Cbl injections for measurement of MMA-to-creatinine concentrations using a gas-liquid chromatography-tandem mass spectrometry (GC-MS) method. RESULTS: All dogs were clinically healthy while receiving monthly and bimonthly OH-Cbl supplementation. Urinary MMA results in healthy dogs ranged from 1.3 to 76.5 mmol/mol creatinine (median, 2.9). Median urinary MMA concentrations did not differ between dogs with IGS receiving monthly (n = 49; 5.3 mmol/mol creatinine; range, 2.3-50.4) and bimonthly (n = 31; 5.3 mmol/mol creatinine; range, 1.6-50) injections. CONCLUSIONS AND CLINICAL IMPORTANCE: A maintenance parenteral dose of 1 mg OH-Cbl monthly or bimonthly appears adequate in Beagles with IGS monitored by metabolic testing.

Characterization of Paroxysmal Gluten-Sensitive Dyskinesia in Border Terriers Using Serological Markers.

BACKGROUND: Paroxysmal gluten-sensitive dyskinesia (PGSD) in border terriers (BTs) results from an immunologic response directed against transglutaminase (TG)2 and gliadin. Recent evidence suggests that PGSD is only one aspect of a range of possible manifestations of gluten sensitivity in the breed. HYPOTHESIS/OBJECTIVES: Gluten sensitivity in BTs is a heterogeneous disease process with a diverse clinical spectrum; to characterize the phenotype of PGSD using TG2 and gliadin autoantibodies as diagnostic markers. ANIMALS: One hundred twenty-eight client-owned BTs with various disorders. METHODS: Prospective study. BTs with paroxysmal episodes and a normal interictal examination were phenotyped using footage of a representative episode and assigned to 3 groups: idiopathic epilepsy (IE), paroxysmal dyskinesia (PD), or other. Owners of each dog completed a questionnaire to obtain information regarding clinical signs. Healthy BTs formed a control group. Serum antibodies against TG2 and AGA were measured in all dogs. RESULTS: One hundred twenty-eight BTs were enrolled; 45 with PD, 28 with IE, 35 with other conditions, and 20 controls. Three overlapping phenotypes were identified; PD, signs suggestive of gastrointestinal disease, and dermatopathy. AGA-IgG concentrations were increased in PD, compared with IE (P = 0.012), controls (P < 0.0001) and other (P = 0.018) conditions. Anti-canine TG2-IgA concentrations were increased in PD, compared with IE (P < 0.0001), controls (P < 0.0001) and other (P = 0.012) conditions. Serological markers are highly specific for PGSD but lack sensitivity. CONCLUSIONS: PGSD appears part of a syndrome of gluten intolerance consisting of episodes of transient dyskinesia, signs suggestive of gastrointestinal disease, and dermatological hypersensitivity.

Systemic Scedosporium prolificans infection in an 11-month-old Border collie with cobalamin deficiency secondary to selective cobalamin malabsorption (canine Imerslund-Gräsbeck syndrome).

An 11-month-old Border collie presented collapsed and continued to deteriorate rapidly despite supportive treatment. The dog had a history of failure to thrive and recurring respiratory infection. Laboratory abnormalities included neutrophilic leucocytosis, Heinz body anaemia, hyperammonaemia, hyperbilirubinaemia, proteinuria and hypocobalaminaemia. Post-mortem examination revealed multi-focal necrosis within the heart, kidneys, pancreas, liver, meninges and cerebral cortex. Fungal hyphae in lesions were identified as Scedosporium prolificans following culture. Subsequent genotyping confirmed that the dog carried the CUBN:c.8392delC mutation in a homozygous state, verifying hereditary cobalamin deficiency (a.k.a. Imerslund-Gräsbeck syndrome). Cobalamin deficiency may have been a predisposing factor for the development of systemic fungal infection in this dog.

Chicken parvovirus viral loads in cloacal swabs from malabsorption syndrome-affected and healthy broilers.

Chicken parvovirus (ChPV) has been associated with malabsorption syndrome (MAS) in broilers. However, the participation of this virus in such syndrome is unclear, since it may be detected in diseased and healthy chickens. In the course of these studies, it was argued whether ChPV genome loads might be correlated to the occurrence of MAS. To check such a hypothesis, a SYBR green-based quantitative polymerase chain reaction was developed to detect and quantify ChPV genomes. Cloacal swabs from 68 broilers with MAS and 59 from healthy animals were collected from different poultry farms. Genomes of ChPV were detected in all samples, regardless of their health status. However, viral genome loads in MAS-affected broilers were significantly higher (1 × 105 genome copies per 100 ng DNA) than in healthy animals (1.3 × 103 GC/100 ng DNA). These findings indicate that there is an association between high ChPV genome loads and the occurrence of MAS in broilers.

Chicken parvovirus and its associations with malabsorption syndrome.

Malabsorption syndrome (MAS) is a multifactorial syndrome which is characterized by enteric disorders and reduced growth rates of broilers. Such condition is responsible for significant economic losses to the poultry industry. A possible association between chicken parvovirus (ChPV) infections and the occurrence of MAS has been proposed. However, such association has not to date been elucidated in view that ChPV has been detected in healthy as well as in MAS-affected chickens. This study aimed to detect and quantify ChPV loads in sera and tissues of MAS-affected, as well as in healthy broilers. Fifty nine, 39-day-old broilers (50 diseased, 9 healthy birds), obtained from the same flocks, were examined. The highest ChPV DNA loads were detected in MAS-affected broilers, particularly in fecal samples and intestinal tissues (~5500 genomic copies/300ng of total DNA). The average viral genome load in serum in MAS-affected birds was 1134copies/mL, whereas no viral DNA was found in sera and thymus tissues from healthy animals. These findings reveal that MAS-affected broilers consistently carry ChPV DNA is serum, whereas healthy animals do not. In addition, viral loads in tissues (bursa of Fabricius, spleen, intestine and liver) of MAS-affected birds were significantly higher in comparison to the same tissues from healthy broilers. Although preliminary, the results obtained here indicate an association between the detection of ChPV DNA in serum, in addition to high ChPV viral loads in tissues, and the occurrence of MAS in broilers. Further experiments should be performed to confirm such results.

Detection of enteric viruses in pancreas and spleen of broilers with runting-stunting syndrome (RSS) / Detecção de vírus entéricos em pâncreas e baço de frangos com a síndrome de nanismo e raquitismo (RSS)

Enteric disease is a multifactorial problem in chickens, which causes gastrointestinal alterations, elevated feed conversions and impairment. In the last years, several enteric viruses were implicated in enteric disease; case reports have shown their presence alone or in concomitant infections during outbreaks and have suggested that they might be determining factors in the aetiology of enteric disease. This study shows high detection rates of enteric viruses in the pancreas and spleen in samples from an outbreak of enteritis and malabsorption in 16 chicken flocks (n=80 broilers). Avian nephritis virus (ANV) was the most ubiquitous virus, present in 75% of the flocks followed by avian rotavirus group A (ART-A) with 68.75%, and by chicken astrovirus (CAstV) and chicken parvovirus (ChPV) in 43.75% of samples. Viruses were present in the pancreas of positive flocks at extremely high rates: 100% for ART-A, 91.7% for ANV, 100% for CAstV and 57.14% for ChPV. By contrast, only 16.7% and 57.14% of intestine samples were positive for ANV and CAstV, respectively. Avian reovirus (AReo) and avian adenovirus group 1 (FAdV-1) were not detected. These results suggest that high viral detection rates in pancreas samples may be a result of viremia during enteric disease, with subsequent damage of the exocrine pancreas, leading to runting-stunting syndrome (RSS).(AU)

A doença entérica é um problema multifatorial em galinhas que causa alterações gastrointestinais, conversão alimentar elevada e deficiência de crescimento. Nos últimos anos, os vírus entéricos foram associados à doença entérica; casos reportados mostraram a infecção de um único vírus e também infecções concomitantes durante os surtos sugerindo a presença de múltiplos fatores etiológicos nas doenças entéricas. Este estudo mostra uma alta taxa de detecção dos vírus entéricos em amostras de pâncreas e baço de um surto de enterite e má-absorção em 16 lotes de frangos (n=80 frangos). O vírus de nefrite aviária (ANV) foi o vírus mais detectado, estando presente em 75% dos lotes seguido pelo rotavírus aviário grupo A (ART-A) em 68,75% dos casos, e pelo astrovirus (CAstV) e parvovírus aviários (ChPV), ambos em 43,75% das amostras. Os vírus estavam presentes no pâncreas dos lotes positivos em percentuais elevados: 100% para ART-A e CAstV; 91,7% para ANV, e em 57,14% para ChPV. Em contraste, somente 16,7% e 57,14%, em amostras de intestino, foram positivos para ANV e CAstV, respectivamente. Reovírus aviário (AReo) e o adenovírus do grupo 1 (FAdV-1) não foram detectados. Estes resultados sugerem que os elevados percentuais de vírus detectados em amostras de pâncreas podem estar associados à viremia durante a doença entérica, com subsequente lesão no pâncreas exócrino das aves levando ao desenvolvimento da síndrome de nanismo e raquitismo.(AU)

Molecular detection of chicken parvovirus in broilers with enteric disorders presenting curving of duodenal loop, pancreatic atrophy, and mesenteritis.

Enteric disorders are an important cause of economic losses in broiler chickens worldwide. Several agents have been associated with enteric problems, such as viruses, bacteria, and parasites. In this study, broiler chickens showing signs of enteric disorders were subjected to molecular diagnosis for several viral agents and also for pathological examination for elucidating this problem. Thus, the chickens were screened for avian nephritis virus (ANV), chicken astrovirus (CAstV), avian rotavirus (ArtV), avian reovirus (AReoV), infectious bronchitis virus (IBV), fowl adenovirus group I (FAdV-1), and chicken parvovirus (ChPV). Postmortem examinations revealed a curving of the duodenal loop (J-like appearance) and intestines filled with liquid and gaseous content. Histopathological analysis of the duodenal loop showed pancreatic atrophy, acute mesenteritis, and enteritis. PCR results showed that ChPV was the sole viral agent detected in samples with lesions such as the curved duodenal loop and pancreatic atrophy. Molecular characterization of the nucleotide and deduced amino acid sequences revealed a high similarity with other strains of ChPV from Brazil, Canada, United States, Europe, and Asia. These findings suggest an association between ChPV and the development of enteritis, pancreatitis, and pancreatic atrophy, which may lead to curling of the duodenal loop. Together, these alterations may disrupt the normal functioning of the digestive system, diminishing digestion and the absorption of dietary nutrients and consequently leading to reduced weight gain, flock impairment, dwarfism, and an elevated feed conversion rate.

Failure to thrive and life-threatening complications due to inherited selective cobalamin malabsorption effectively managed in a juvenile Australian shepherd dog.

A juvenile Australian shepherd dog exhibited failure to grow, inappetence, weakness, nonregenerative anemia, neutropenia, and cobalamin deficiency. DNA testing confirmed homozygosity of an amnionless mutation (AMN c.3G > A). Clinical signs resolved with supportive care and parenteral cobalamin supplementation. Inherited selective intestinal cobalamin malabsorption requiring lifelong parenteral supplementation should be considered in Australian shepherds, giant schnauzers, border collies, and beagles that fail to thrive.

Gestion efficace d'un retard de croissance et de complications potentiellement mortelles attribuables à une malabsorption de cobalamine sélective héréditaire chez un jeune chien Berger australien. Un jeune chien Berger australien a manifesté une absence de croissance, de l'inappétence, de la faiblesse, une anémie non régénérative, de la neutropénie et une déficience de cobalamine. Des tests d'ADN ont confirmé l'homozygotisme d'une mutation des récepteurs amnionless (AMN c.3G > A). Les signes cliniques se sont résorbés avec des soins de soutien et des suppléments de cobalamine parentéraux. Une malabsorption intestinale sélective héréditaire de cobalamine exigeant des suppléments parentéraux à vie devrait être considérée chez les Bergers australiens, les Schnauzers géants, les Border-Collies et les Beagles qui manifestent des problèmes de croissance.(Traduit par Isabelle Vallières).

Methylmalonic Aciduria Secondary to Selective Cobalamin Malabsorption in a Yorkshire Terrier.

An 8 wk old male Yorkshire terrier was presented with a 2 wk history of recurrent hypoglycemia, lethargy, and seizures. Investigations revealed a marked increase in blood ammonia, low serum cobalamin, and increased levels of urinary methylmalonic acid (MMA) excretion. No liver vascular abnormality was detected. The patient was diagnosed with methylmalonic aciduria due to cobalamin malabsorption. The patient responded well to parenteral cobalamin administration, and the urinary MMA levels normalized rapidly following instigation of treatment. Due to the suspected hereditary nature of selective cobalamin deficiency, one sibling of this dog was screened and found to be normal. This is the first reported case of MMA secondary to hypocobalaminemia in Yorkshire terriers, and the second report of this disease in a dog in the United Kingdom. Given the fact that clinical signs of MMA are similar to those seen in dogs with portosystemic shunts and that Yorkshire terriers are predisposed to liver vascular abnormalities, this case report adds important clinical information to the current available literature.

Hepatic fungal infection in a young beagle with unrecognised hereditary cobalamin deficiency (Imerslund-Gräsbeck syndrome).

A 12-month-old beagle presented for anorexia, pyrexia and vomiting. The dog had been treated intermittently with antibiotics and corticosteroids for inappetence and lethargy since five months of age. Previous laboratory abnormalities included macrocytosis and neutropenia. At presentation, the dog was lethargic, febrile and thin. Laboratory examination findings included anaemia, a left shift, thrombocytopenia, hypoglycaemia and hyperbilirubinaemia. Multiple, small, hypoechoic, round hepatic lesions were observed on abdominal ultrasound. Cytological examination of hepatic fine needle aspirates revealed a fungal infection and associated pyogranulomatous inflammation. The dog's general condition deteriorated despite supportive measures and treatment with fluconazole, and owners opted for euthanasia before hypocobalaminaemia was identified. Subsequent genomic analysis revealed a CUBN:c.786delC mutation in a homozygous state, confirming hereditary cobalamin malabsorption (Imerslund-Gräsbeck syndrome). Similar to human infants, dogs with Imerslund-Gräsbeck syndrome may rarely be presented for infectious diseases, distracting focus from the underlying primary disorder.

Impacts of the feed contaminant deoxynivalenol on the intestine of monogastric animals: poultry and swine.

Deoxynivalenol (DON) is one of the most prevalent cereal contaminants with major public health concerns owing to its high toxigenic potentials. Once ingested, DON first and foremost targets epithelial cells of the gastrointestinal tract, whose proper functioning, as the first line of defence, is of paramount importance for the host's health. Emerging evidences, summarized in this article, suggest that DON produces its toxicity primarily via activation of the mitogen-activated protein kinases (MAPKs) signalling pathway and alteration in the expression of genes responsible for key physiological and immunological functions of the intestinal tissue of chickens and pigs. The activation of MAPKs signalling cascade results in disruption of the gut barrier function and an increase in the permeability by reducing expression of the tight junction proteins. Exposure to DON also down-regulates the expression of multiple transporter systems in the enterocytes with subsequent impairment of the absorption of key nutrients. Other major intestinal cytotoxic effects of DON described herein are modulation of mucosal immune responses, leading to immunosupression or stimulation of local immune cells and cytokine release, and also facilitation of the persistence of intestinal pathogens in the gut. Both of the last events potentiate enteric infections and local inflammation in pigs and poultry, rendering enterocytes and the host more vulnerable to luminal toxic compounds. This review highlights the cytotoxic risks associated with the intake of even low levels of DON and also identifies gaps of knowledge that need to be addressed by future research.

Selective intestinal cobalamin malabsorption with proteinuria (Imerslund-Gräsbeck syndrome) in juvenile Beagles.

BACKGROUND: Selective intestinal cobalamin malabsorption with mild proteinuria (Imerslund-Gräsbeck syndrome; I-GS), is an autosomal recessive disorder of dogs caused by mutations in AMN or CUBN that disrupt cubam function and which can present as a medical emergency. OBJECTIVES: To describe the clinical, metabolic, and genetic bases of I-GS in Beagles. ANIMALS: Four cobalamin-deficient and 43 clinically normal Beagles and 5 dogs of other breeds. METHODS: Clinical description and candidate gene genetic study. Urinary organic acid and protein excretion were determined by gas-chromatography and SDS-PAGE, respectively. Renal cubilin protein expression was assessed on immunoblots. Mutation discovery was carried out by PCR amplification and DNA sequencing of exons with flanking splice sites and cDNA of CUBN and AMN. Genotyping was performed by restriction enzyme digestion of PCR amplicons. RESULTS: Juvenile-affected Beagles exhibited failure to thrive, dyshematopoiesis with neutropenia, serum cobalamin deficiency, methylmalonic aciduria, hyperammonemia, and proteinuria. Affected dogs' kidneys lacked detectable cubilin protein. All affected dogs were homozygous for a single-base deletion in CUBN exon 8 (CUBN c.786delC), predicting a translational frameshift, and the 2 parents tested were heterozygous. CONCLUSIONS: The CUBN mutation in juvenile I-GS Beagles causes a more severe cobalamin malabsorption than in Border Collies with a different CUBN defect, but is similar to I-GS caused by AMN mutations in Giant Schnauzers and Australian Shepherds. Awareness of the disorder and breed predispositions to I-GS is crucial to precisely diagnose and promptly treat hereditary cobalamin malabsorption and to prevent disease in those dogs at risk in future generations.

A frameshift mutation in the cubilin gene (CUBN) in Beagles with Imerslund-Gräsbeck syndrome (selective cobalamin malabsorption).

Mammals are unable to synthesize cobalamin or vitamin B12 and rely on the uptake of dietary cobalamin. The cubam receptor expressed on the intestinal endothelium is required for the uptake of cobalamin from the gut. Cubam is composed of two protein subunits, amnionless and cubilin, which are encoded by the AMN and CUBN genes respectively. Loss-of-function mutations in either the AMN or the CUBN gene lead to hereditary selective cobalamin malabsorption or Imerslund-Gräsbeck syndrome (IGS). We investigated Beagles with IGS and resequenced the whole genome of one affected Beagle at 15× coverage. The analysis of the AMN and CUBN candidate genes revealed a homozygous deletion of a single cytosine in exon 8 of the CUBN gene (c.786delC). This deletion leads to a frameshift and early premature stop codon (p.Asp262Glufs*47) and is, thus, predicted to represent a complete loss-of-function allele. We tested three IGS-affected and 89 control Beagles and found perfect association between the IGS phenotype and the CUBN:c.786delC variant. Given the known role of cubilin in cobalamin transport, which has been firmly established in humans and dogs, our data strongly suggest that the CUBN:c.786delC variant is causing IGS in the investigated Beagles.