Precision medicine using whole genome sequencing in a cat identifies a novel COL5A1 variant for classical Ehlers-Danlos syndrome.

BACKGROUND: Ehlers-Danlos syndromes (EDS) are a heterogeneous group of heritable connective tissue disorders occurring in both human and veterinary patients. The genetics of these disorders are poorly described in small animal patients. HYPOTHESIS/OBJECTIVES: Define the clinical manifestations and genetic cause of a suspected form of EDS in a cat. ANIMALS: A 14-week-old male domestic medium hair cat was presented with skin hyperextensibility and fragility. The classic tragic facial expression was observed as well as chronic pruritus and mild hyperesthesia. METHODS: Blood samples and a skin biopsy sample were collected from the affected cat. Clinical examinations, histology, electron microscopy and whole genome sequencing were conducted to characterize the clinical presentation and identify possible pathogenic DNA variants to support a diagnosis. Criteria defining variant pathogenicity were examined including human disease variant databases. RESULTS: Histology showed sparse, disorganized collagen and an increase in cutaneous mast cells. Electron microscopy identified ultrastructural defects commonly seen in collagen type V alpha 1 chain (COL5A1) variants including flower-like collagen fibrils in cross-section. Whole genome sequencing and comparison with 413 cats in the 99 Lives Cat Genome Sequencing Consortium database identified a novel splice acceptor site variant at exon 4 in COL5A1 (c.501-2A>C). CONCLUSIONS AND CLINICAL IMPORTANCE: Our report broadens the current understanding of EDS in veterinary patients and supports the use of precision medicine techniques in clinical veterinary practice. The classification of variants for pathogenicity should be considered in companion animals.

Identification of an ADAMTS2 frameshift variant in a cat family with Ehlers-Danlos syndrome.

We investigated 4 European domestic shorthair kittens with skin lesions consistent with the dermatosparaxis type of the Ehlers-Danlos syndrome, a connective tissue disorder. The kittens were sired by the same tomcat but were born by 3 different mothers. The kittens had easily torn skin resulting in nonhealing skin wounds. Both clinically and histologically, the skin showed thin epidermis in addition to inflammatory changes. Changes in collagen fibers were visible in electron micrographs. The complete genome of an affected kitten was sequenced. A one base pair duplication leading to a frameshift in the candidate gene ADAMTS2 was identified, p.(Ser235fs*3). All 4 affected cats carried the frameshift duplication in a homozygous state. Genotypes at this variant showed perfect cosegregation with the autosomal recessive Ehlers-Danlos syndrome phenotype in the available family. The mutant allele did not occur in 48 unrelated control cats. ADAMTS2 loss-of-function variants cause autosomal recessive forms of Ehlers-Danlos syndrome in humans, mice, dogs, cattle, and sheep. The available evidence from our investigation together with the functional knowledge on ADAMTS2 in other species allows to classify the identified ADAMTS2 variant as pathogenic and most likely causative variant for the observed Ehlers-Danlos syndrome.

Connective Tissue Disorders in Domestic Animals.

Though soft tissue disorders have been recognized and described to some detail in several types of domestic animals and small mammals for some years, they remain uncommon. Because of their low prevalence, not much progress has been made not only in improved diagnosis but also in our understanding of the biochemical basis and pathogenesis of these diseases in animals. Ehlers-Danlos syndrome (EDS) described in dogs already in 1943 and later in cats has only minor impact on the well-being of the dog as its effects on skin of these animals are rather limited. The involved skin is thin and hyperextensible with easily inflicted injuries resulting in hemorrhagic wounds and atrophic scars. Joint laxity and dislocation common in people are less frequently found in dogs. No systemic complications, such as organ rupture or cardiovascular problems which have devastating consequences in people have been described in cats and dogs. The diagnosis is based on clinical presentation and on light or electron microscopic features of disorganized and fragmented collagen fibrils. Several case of bovine and ovine dermatosparaxis analogous to human Ehlers-Danlos syndrome type VIIC were found to be caused by mutations in the procollagen I N-proteinase (pnPI) or ADAMTS2 gene, though mutations in other sites are likely responsible for other types of dermatosparaxis. Cattle suffering from a form of Marfan syndrome (MFS) were described to have aortic dilatation and aneurysm together with ocular abnormalities and skeletal involvement. As in people, mutations at different sites of bovine FBN1 may be responsible for Marfan phenotype. Hereditary equine regional dermal asthenia (HERDA), or hyperelastosis cutis, has been recognized in several horse breeds as affecting primarily skin, and, occasionally, tendons. A mutation in cyclophilin B, a chaperon involved in proper folding of collagens, has been identified in some cases. Warmblood fragile foal syndrome (WFFS) is another Ehlers-Danlos-like disorder in horses, affecting primarily Warmbloods who present with skin fragility and joint hyperextensibility. Degenerative suspensory ligament desmitis (DSLD) affects primarily tendons and ligaments of certain horse breeds. Data from our laboratory showed excessive accumulation of proteoglycans in organs with high content of connective tissues. We have identified increased presence of bone morphogenetic protein 2 (BMP2) in active foci of DSLD and an abnormal form of decorin in proteoglycan deposits. Our most recent data obtained from next generation sequencing showed disturbances in expression of genes for numerous proteoglycans and collagens.

A homozygous ADAMTS2 nonsense mutation in a Doberman Pinscher dog with Ehlers Danlos syndrome and extreme skin fragility.

An eight-week old Doberman Pinscher was diagnosed with Ehlers Danlos syndrome based on the dog's hyper-mobile carpal, tarsal and stifle joints and abnormal skin. The skin was loose and hyper-elastic with several wounds and large atrophic scars. The dog was euthanized after a severe degloving injury from minimal trauma. A whole-genome sequence, generated with DNA from the dog's blood, contained a rare, homozygous C-to-T transition at position 2408978 on chromosome 11. This transition is predicted to alter the ADAMTS2 transcript (ADAMTS2:c.769C>T) and encode a nonsense mutation (p.Arg257Ter). Biallelic ADAMTS2 mutations have caused a type of Ehlers Danlos syndrome known as dermatosparaxis in other species.

Dermatosparaxis in two Limousin calves.

BACKGROUND: An unusual presentation of skin disease was identified in two related neonatal Pedigree Limousin calves presented to University Veterinary Hospital, University College Dublin, following detailed post mortem examination a diagnosis of dermatosparaxis was made. Dermatosparaxis in animals or Ehlers Danlos Syndrome, which is the analogous condition seen in humans, is a connective tissue disorder characterised by extreme skin fragility. To the authors' knowledge this is the first report of such a diagnosis in the Limousin breed and the features of this lethal phenotype were severe in comparison to previous reports of the condition. CASE PRESENTATION: Two calves, which were full siblings, a pedigree Limousin bull (Calf A) and pedigree Limousin heifer (Calf B) were examined clinically after presenting collapsed since birth, both had grossly abnormal skin with multiple skin fissures visible and both calves were subsequently euthanised. Both calves underwent gross post mortem examination, after which histological samples were reviewed and electron microscopical examination of selected skin samples was carried out. Histological features of dysplastic dermal collagen were identified. The diagnosis of dermatosparaxis in the Limousin breed was confirmed. Genetic testing was conducted to determine if the current cases had the same mutation as has previously been described in Belgian Blue cattle. Some common parentage was traced but genetic testing did not show a similar mutation to that previously described in cattle. The specific genetic cause in this case is unknown. CONCLUSIONS: This is the first report of dermatosparaxis in the Limousin and the presentation of the dermatosparaxis phenotype has some noteworthy features thus further genetic testing is required to pinpoint the causative mutation or other genetic defect. Given the popularity of the breed and the lethal nature of the phenotype in this case it is important to raise awareness of the condition.

Dermatosparaxis in two White Doper lambs in Brazil: case report / Dermatosparaxis em dois cordeiros White Dorper no Brasil: relato de caso

Dermatosparaxis is a genetic disease that affects collagen maturation. This disease is characterized by marked impairment of the resistance of collagen fibers that leads to skin fragility, and it may affect several species. This is the first report of dermatosparaxis in sheep in Brazil. Clinically, two White Dorper lambs had multiple skin lacerations in the neck, dorsum and limbs. Transmission microscopy demonstrated irregular collagen fibers arranged in hieroglyphic shape and scanning electron microscopy demonstrated thin collagen fibrils that were not arranged in bundles as observed in the normal dermis. These findings are consistent with the diagnosis of dermatosparaxis.

A dermatosparaxis é uma doença genética que afeta a maturação do colágeno. Essa doença é caracterizada por redução acentuada da resistência das fibras colágenas que leva à fragilidade da pele. Esse é o primeiro relato de dermatosparaxis em ovinos no Brasil. Clinicamente, dois cordeiros da raça White Dorper tiveram múltiplas lacerações na pele do pescoço, dorso e membros. A microscopia de transmissão demonstrou fibras de colágeno irregularares arranjadas em formato de hieroflifo, e a microscopia de varredura demonstrou fibras finas de colágeno não arranjadas em bandas como na derme do animal normal. Esses achados são consistentes com o diagnóstico de dermatosparaxis.

Aspectos clínicos, histopatológicos e moleculares da dermatosparaxia em ovinos White Dorper / Clinical, histopathological and molecular aspects of the dermatosparaxis in White Dorper sheep

Dermatosparaxia em animais é uma doença autossômica recessiva do tecido conjuntivo caracterizada por fragilidade e hiperextensibilidade cutânea. A doença em ovinos White Dorper é provocada pela mutação c.421G>T no gene ADAMmetalopeptidase com trombospondina tipo 1 motif, 2 (ADAMTS2). O objetivo deste estudo foi descrever os achados clínicos, moleculares e histopatológicos da dermatosparaxia em ovinos White Dorper de um rebanho localizado no Centro-Oeste Paulista. [...] Dos nove animais examinados, dois apresentavam sinais clínicos compatíveis com dermatosparaxia. O exame histopatológico de amostras cutâneas das lesões destes dois animais revelou também achados compatíveis com dermatosparaxia, sendo caracterizados por epiderme e anexos cutâneos preservados e sem características atípicas; colágeno displásico arranjado em feixes pequenos, fragmentados e com focos de degeneração, anexos cutâneos proeminentes e na região da derme foco hemorrágico intenso associado a moderado infiltrado neutrofílico na derme profunda. Com o objetivo de realizar o diagnóstico molecular da enfermidade, uma PCR foi padronizada utilizando primers específicos desenhados para amplificar a região do gene ADAMTS2 que continha a mutação c.421G>T e o DNA obtido de amostras de sangue de todos os animais do rebanho. O sequenciamento direto dos produtos da PCR, comprovou que os dois animais clinicamente afetados possuíam a mutação responsável pela dermatosparaxia. A metodologia descrita neste estudo possibilitou o diagnóstico definitivo da doença. Segundo a literatura consultada, esta é a primeira vez que a dermatosparaxia é descrita em ovinos White Dorper no Brasil. A metodologia aqui descrita poderá ser empregada em estudos futuros que avaliem a prevalência desta mutação no Brasil, possibilitando a adoção de medidas que previnam a disseminação dessa mutação no rebanho brasileiro de ovinos White Dorper.

Dermatosparaxis in animals is an autosomal recessive disorder of the connective-tissue clinically characterized by skin fragility and hiperextensibility. The disease in White Dorper sheep is caused by mutation (c.421G>T) in the ADAM metalloproteinase with thrombospondin type 1 motif, 2 (ADAMTS2) gene. This study describes the dermatological, histological and the molecular findings of the dermatosparaxis in White Dorper sheep from a herd located in the center-west of São Paulo State. [...] The herd consisted of one ram, four ewe and their lambs. In this herd two lambs had clinical signs consistent with dermatosparaxis. Histopathological evaluation of the affected skin of these two animals also revealed consistent findings with dermatosparaxis, characterized by dysplasia of the collagen, which were arranged in small and fragmented collagen bundles and with foci of degeneration of collagen. Prominent cutaneous appendages and severe hemorrhagic focus in dermis region associated with mild neutrophilic infiltrate in the deep dermis. PCR using DNA blood and specific primers to amplify the mutation region c.421G>T was optimized in order to perform molecular diagnosis of the disease. The direct sequencing of the PCR products proved that the two clinically affected animals had the mutation responsible for dermatosparaxis, previously described for this breed and allowed the definitive diagnosis of the disease. This is the first report of the dermatosparaxis in White Dorper sheep in Brazil and the methodology used to confirm the diagnosis could be used in future studies to assess the prevalence of this mutation in Brazil, allowing the adoption of measures to prevent the spread of this mutation in the Brazilian White Dorper herd.

Ehlers-Danlos Syndrome Type VIIC: A Mexican Case Report.

Ehlers-Danlos syndrome (EDS) is a heterogeneous group of heritable connective tissue disorders whose primary clinical features include soft and extensible skin, articular hypermobility and tissue fragility. EDS type VIIC or 'human dermatosparaxis' is an autosomal recessive disease characterized by severe skin fragility and sagging redundant skin (major criteria) with a soft, doughy texture, easy bruising, premature rupture of fetal membranes and large hernias (minor criteria). Dermatosparaxis (meaning 'tearing of skin'), which has been described in several non-human species, is a disorder of the connective tissue resulting from a deficiency of the enzyme that cleaves the registration peptide off the N-terminal end of collagen after it has been secreted from fibroblasts. We describe a Mexican case from consanguineous parents with all the phenotypical characteristics previously described, plus skeletal abnormalities.