Categories: Behaviour / neurological phene

Mendelian trait/disorder: unknown

Disease-related: yes

Species-specific description: Shackelford, R.M., Cole, L.J. (1947): "Individuals affected with screw neck show the symptoms of this condition by carrying the head tilted habitually either to the right, or to the left, or in some individuals by tilting it first one way and then the other. When turning around in a cage ... the head is thrown directly over the shoulder or back. ... Screw neck is apparently one of the effects of the pastel mutation which expresses itself in only about 25 per cent of the individuals that are homozygous for the pastel gene."