Ullrich-type muscular dystrophy is a severe myopathy caused by loss of function of collagen VI, an extracellular matrix protein. In the Landseer it is due to a nonsense variant in the COL6A1 gene and is characterized by progressive muscle weakness and atrophy of early onset. It is inherited in an autosomal recessive manner and is the canine equivalent of human Ullrich congenital muscular dystrophy.

Described in the Landseer. The variant was not detected in 404 Newfoundland dogs or in 473 dogs of other breeds genotyped by Steffen et al. (2015), suggesting a breed-restricted distribution.

- Progressive muscle weakness and atrophy\n- Altered gait and exercise intolerance\n- Joint stiffness and contractures\n- Generalized muscle atrophy\n- Signs of early onset

Steffen et al. (2015) described the clinical picture, pathology and genetics of Landseer dogs with severe muscular dystrophy and, by whole-genome sequencing, identified a nonsense variant in COL6A1 (c.289G>T; p.E97*) that co-segregated with the phenotype. Brands et al. (2021) later characterized this canine model of Ullrich congenital muscular dystrophy.

- Test Landseer breeders\n- Do not cross two carriers: 25 % of the litter would be affected homozygotes\n- A carrier may be crossed with a clear dog, testing the offspring intended for breeding\n- Do not breed affected dogs

Differential diagnosis with other hereditary muscular dystrophies. COL6A1 dystrophy is autosomal recessive, unlike Duchenne muscular dystrophy (X-linked, DMD gene). The reduction of collagen VI can be documented by immunohistochemistry in a muscle biopsy.

1. Steffen F et al. 2015. A Nonsense Variant in COL6A1 in Landseer Dogs with Muscular Dystrophy. G3 (Bethesda). PMID: 26438297
2. Brands J et al. 2021. COL6A1 related muscular dystrophy in Landseer dogs: A canine model for Ullrich congenital muscular dystrophy. Muscle & Nerve. PMID: 33382107
3. OMIA:001967-9615. Muscular dystrophy, Ullrich type, COL6A1-related. Online Mendelian Inheritance in Animals.