This spontaneous mutation was proven allelic with the original quivering mutation by a noncomplementation test. Sequencing of the Spnb4 gene only detected three silent third-base polymorphisms in the coding region and these polymorphisms can be identified in unaffected inbred strains.
Legend:
cx: complex: > 1 genome feature ot: other: hemizygous, indeterminate,... (F): Female
(M): Male
N: normal phenotype
(#): related diseases count