In other species: dog , domestic cat , horse , pig , taurine cattle , goat , water buffalo

Categories: Muscle phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 160800 (trait) , 255700 (trait) , 118425 (gene)

Single-gene trait/disorder: yes

Mode of inheritance: Autosomal recessive

Disease-related: yes

Key variant known: yes

Year key variant first reported: 2015

Cross-species summary: Myotonia congenita

Molecular basis: Using a comparative candidate gene approach (based on the same clinical signs being due to mutations in CLCN1 in goats, horse and humans [see related entries at the top of this page]), Monteagudo et al. (2015) sequenced this gene in two affected lambs and three unrelated unaffecteds from Spanish flocks of the Rasa Aragonesa breed. They reported "In the second exon, a g.106140081G>A transversion was found in homozygosity in both affected individuals (GenBank number NC_019461.1 numbering), resulting in a p.Gln93Lys substitution in the amino acid sequence. Both lambs were born from ewes heterozygous for this SNV (GA), verified by DNA sequencing. Five of the 27 rams in service at the farm were also found to be heterozygous GA, while the remainder was homozygous GG. No AA individuals were detected among the adult individuals." 40 unrelated rams from other flocks were homozygous GG. Importantly, "Removing the GA rams in May 2013 and replacing them with GG rams from the same flock allowed us to prevent occurrence of homozygous AA new-born lambs in the flock and to confirm association between the SNV [single nucleotide variant] and the pathology. As of 22 December 2014, no additional affected lambs had been born, further supporting the role of this SNV in the pathology."

Clinical features: As reported by et al. (2015) "The symptoms were visible only after sudden visual and/or auditory stimulation or fast movements during normal flock management. When other individuals in the lot started evasive movements, the affected lambs maintained a rigid position with extended limbs and frequently fell to the ground. After 6–25 s, the lambs were able to stand and move normally."

Breeds: Merino (Sheep) (VBO_0001508), Rasa Aragonesa, Spain (Sheep) (VBO_0015863).
Breeds in which the phene has been documented. (If a likely causal variant has been documented for the phene, see the variant table breeds in which the variant has been reported).

Associated gene: