The clench (CL) is a new morphological mutation in Japanese quail (Cot
urnix japonica). The CL mutants rigidly clench their toes in both legs
, which gives rise to a human fistlike appearance in the distal ends o
f the legs. Other parts of the CL body are quite normal. In spite of t
he severe toe abnormality, the CL mutants are normal in fertility, hat
chability, and post natal viability. Genetic analysis revealed that th
e CL mutation is an autosomal recessive with 100% penetrance. The prop
osed gene symbol is cl.