Categories: Muscle phene

Mendelian trait/disorder: yes

Mode of inheritance: Autosomal dominant

Disease-related: no

Key variant known: no

Cross-species summary: Abnormal increase in muscular tissue caused entirely by enlargement of existing cells (in contrast to muscular hyperplasia, in which the abnormal increase in muscular tissue is due to the formation and growth of new, normal muscle cells)

Species-specific name: Carwell; rib-eye muscling (REM)

History: In the first stage of a Poll Dorset nucleus breeding program commenced in 1989 in Australia, progeny of sires of the Carwell stud exhibited extreme muscling (Banks, 1997). Subsequent segregation analysis implicated a single gene of large effect (Banks, unpublished). Given the similarity of phenotype to the Callipyge mutation which by then had been mapped to chromosome 18, linkage study showed that the Carwell locus also maps to chromosome 18 (Banks, unpublished). Subsequent New Zealand research (Nicoll et al., 1998) provided evidence that suggested Carwell may be allelic with Callipyge, but that the hypertrophy is restricted to the longissimus dorsi muscle, which is 8% larger. McLaren et al. (2001) identified some positional candidate genes [FN and Rob Banks; 10 Nov 2002]

Inheritance: Jopson et al. (2001) reported autosomal dominant inheritance.

Mapping: Tellam et al. (2012) reported that "The [Carwell] QTL is positioned 2–6 cM telomeric to the CSSM18 marker on OAR18 and overlaps with the site of the Callipyge mutation" (OMIA 001354-9940)

Markers: y

Clinical features: Summarising the findings of Nicoll et al. (1998) and Greenwood et al. (2006), Tellam et al. (2012) reported "The Carwell (or rib eye muscling,REM) locus identified in Australian Poll Dorset rams is associated with increased muscle depth of longissimus dorsi (also named longissimus lumborum) with no effect on fatness or liveweight. There is also a change in muscle shape and a shift from type IIa towards type IIb and IIx muscle fibers"

Breed: Poll Dorset (Sheep) (VBO_0001557).
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).