onychogryphosis
ram's horn nails

Severe congenital onychogryphosis affecting all twenty nailbeds has been recorded in two families, who exhibit the dominant allele for a certain gene.

Congenital onychogryphosis of the fifth toe (the little toe) is fairly common, but asymptomatic and seldom brought to the attention of medical professionals.

Onychogryphosis (also known as "ram's horn nails") is a hypertrophy that may produce nails resembling claws or a ram's horn, possibly caused by trauma or peripheral vascular disorders, but most often secondary to neglect and failure to cut the nails for extended periods of time.