Accessory nail of the fifth toe

[4] The cause is poorly understood due to a lack of research, but genome-wide scans indicate that it is a heritable trait, and could be autosomal dominant.

[5] In some cases, the accessory nail presents with an abnormal protrusion or distortion of the fifth distal phalanx, or the splaying or rotation of the toe or entire foot.

[4] Ena et al. proposed the diagnostic criteria have 4 components: presence at birth, potential inheritance, involvement of the fifth toe, and bilaterality.

[4] For those who do choose treatment, an option is surgical or chemical matricectomy (complete removal or destruction of the nail matrix).

Yin Wang stabbed her in the abdomen as she tried to escape, so she gave birth to two children with a scar on the small toe of the foot.

The children were taken back by Yin Wang for adoption, and their descendants were born with double nails on their small toes.