Onychogryphosis may be caused by trauma or peripheral vascular disease, but most often secondary to self-neglect and failure to cut the nails for extended periods of time.[2][4] This condition is most commonly seen in the elderly.
Severe congenital onychogryphosis affecting all twenty nailbeds has been recorded in two families who exhibit the dominant allele for a certain gene.[6][7] Congenital onychogryphosis of the fifth toe (the baby, little, pinky or small toe) is fairly common, but asymptomatic and seldom brought to the attention of medical professionals. Rather, it is brought to the attention of manicurists who routinely file the clawed toenail flat.