Novel frameshift variant in exon 7 of COL17A1 in a domestic shorthair kitten with junctional epidermolysis bullosa.

Junctional epidermolysis bullosa (JEB) is a congenital blistering skin disorder with clefting within the lamina lucida of the basement membrane zone. We describe the clinical and morphologic features of JEB in a 4-mo-old domestic shorthair kitten and identify the underlying genetic variant. The kitten was presented with blistering lesions affecting friction-prone areas of haired skin, mucocutaneous junctions, and oral mucosa. Histopathology revealed extensive subepidermal cleft formation in affected tissues. Periodic acid-Schiff (PAS) staining showed a thin, PAS-positive line along the dermal side of the cleft, consistent with retention of the lamina densa. Transmission electron microscopy confirmed separation at the level of the lamina lucida with intact basal keratinocytes. Whole genome sequencing identified a homozygous 2-bp deletion in exon 7 of COL17A1, predicted to result in loss of function and disrupted binding domains. Our findings support a diagnosis of JEB associated with a novel COL17A1 variant.