Dataset Information

LAMB3 Missense Variant in Australian Shepherd Dogs with Junctional Epidermolysis Bullosa.

ABSTRACT: In a highly inbred Australian Shepherd litter, three of the five puppies developed widespread ulcers of the skin, footpads, and oral mucosa within the first weeks of life. Histopathological examinations demonstrated clefting of the epidermis from the underlying dermis within or just below the basement membrane, which led to a tentative diagnosis of junctional epidermolysis bullosa (JEB) with autosomal recessive inheritance. Endoscopy in one affected dog also demonstrated separation between the epithelium and underlying tissue in the gastrointestinal tract. As a result of the severity of the clinical signs, all three dogs had to be euthanized. We sequenced the genome of one affected puppy and compared the data to 73 control genomes. A search for private variants in 37 known candidate genes for skin fragility phenotypes revealed a single protein-changing variant, LAMB3:c.1174T>C, or p.Cys392Arg. The variant was predicted to change a conserved cysteine in the laminin ?3 subunit of the heterotrimeric laminin-322, which mediates the binding of the epidermal basement membrane to the underlying dermis. Loss-of-function variants in the human LAMB3 gene lead to recessive forms of JEB. We confirmed the expected co-segregation of the genotypes in the Australian Shepherd family. The mutant allele was homozygous in two genotyped cases and heterozygous in three non-affected close relatives. It was not found in 242 other controls from the Australian Shepherd breed, nor in more than 600 other controls. These data suggest that LAMB3:c.1174T>C represents the causative variant. To the best of our knowledge, this study represents the first report of a LAMB3-related JEB in domestic animals.

SUBMITTER: Kiener S

PROVIDER: S-EPMC7565164 | biostudies-literature | 2020 Sep

REPOSITORIES: biostudies-literature

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<i>LAMB3</i> Missense Variant in Australian Shepherd Dogs with Junctional Epidermolysis Bullosa.

Kiener Sarah S Laprais Aurore A Mauldin Elizabeth A EA Jagannathan Vidhya V Olivry Thierry T Leeb Tosso T

Genes 20200907 9

In a highly inbred Australian Shepherd litter, three of the five puppies developed widespread ulcers of the skin, footpads, and oral mucosa within the first weeks of life. Histopathological examinations demonstrated clefting of the epidermis from the underlying dermis within or just below the basement membrane, which led to a tentative diagnosis of junctional epidermolysis bullosa (JEB) with autosomal recessive inheritance. Endoscopy in one affected dog also demonstrated separation between the e ...[more]

PMID: 32906717

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Project description:RATIONALE:Epidermolysis bullosa (EB) refers to a group of rare inherited mechanobullous disorders that present with great clinical and genetic heterogeneity. Its severity ranges from mild blistering to life-threatening. However, the clinical symptoms of different types of EB overlap significantly, especially at an early stage. Thus it is important to clarify the diagnosis for prognostic implications, patient management, and genetic counseling. PATIENT CONCERNS:Here, we report a 10-day-old male neonate from a nonconsanguineous Chinese family. He showed a bulla on the left lower limb lasting for 3 days, erosions around fingertips and toe tips at birth (predominantly on fingers), with the progressive spread of generalized blisters over the body as well as the development of the illness. DIAGNOSIS:The patient was diagnosed with suspected epidermolysis bullosa according to the blisters and erosions of the body as well as the pyogenic fingernails and toenails. INTERVENTIONS:The patient was performed targeted next-generation sequencing (NGS) with 9 candidate known genes, subsequently, his parents were screened for the mutations identified in the patient by Sanger sequencing. Then, prenatal diagnosis with amniotic fluid was performed in the subsequent pregnancy by Sanger sequencing. OUTCOMES:Targeted NGS revealed a previously unreported splice site variant c.822+1G>A (IVS 8) and a known recurrent nonsense variant c.124C>T (p.Arg42Ter, exon 3) in LAMB3 gene. The patient's father possessed a heterozygous c.822+1G>A mutation, his mother possessed a heterozygous c.124C>T mutation. For the subsequent pregnancy, the analyses of amniotic fluid sample indicated that the fetus carried neither of the mutations. LESSONS:Our finding will further enlarge LAMB3 genotype-phenotype correlations spectrum. Targeted capture sequencing is a valuable method to illustrate precise molecular pathology in patients with EB disorders, especially at an early stage of the clinical evaluation of complex disorders to avoid unnecessary and economically wasteful tests.

Dataset Information

LAMB3 Missense Variant in Australian Shepherd Dogs with Junctional Epidermolysis Bullosa.

Publications

<i>LAMB3</i> Missense Variant in Australian Shepherd Dogs with Junctional Epidermolysis Bullosa.

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