He observed that the polydactyly phenotype showed "good penetrance, but variable expression" because the gene always causes extra toes on the paw, but the number of extra toes varies widely from ...

One form of dwarfism, Ellis-van Creveld syndrome, involves not only short stature but polydactyly (extra fingers ... which require two copies of the gene to cause the disease, will show up more ...

There's no concrete evidence to suggest a direct cause for polydactyly. Most research states that the condition is usually ...