Accessory nail of the fifth toe

An accessory toenail on a right foot

The accessory nail of the fifth toe, also known as petaloid toenail, is a physical trait of the small toe, where a minuscule "sixth toenail" is present in the outer corner of the nail situated on the smallest toe.

Trait

The trait can be observed on either one or both feet, where there is a separation of the toenail situated on the smallest toe. The separated part of the nail forms a smaller "sixth toenail" on the corner of the larger, or "main" section of the toenail, on the outermost side of the foot, which protrudes outwards from the corner of the larger nail. The additional "nail" can be cut with a nail clipper, just like any other nail.

Genome-wide scans indicate that it is a heritable trait. However, instead of following a Mendelian pattern of inheritance, it is likely to be a complex trait affected by multiple genes with minor genetic effects. [1]

Removal

Many people do not request or seek out removal, as the accessory nail typically does not cause symptoms.[2] Surgical or chemical matricectomy, or complete removal or destruction of the nail matrix, has been used for successful removal of the accessory toenail.[3][2][4]

Legend

While it was thought to be a prevalent feature amongst Han Chinese,[3] it is observed in people from all ethnicities and races.

Chinese mythology follows that during the time of the Yellow Emperor, there were two types of people living in China, those who were the descendants of the Yellow Emperor, and those who were nomadic Qiang people. As the Henan people attacked the Qiang, led by Yin Wang, they abducted a Qiang woman, who later tried to escape. After Yin Wang stabbed her in the abdomen as she tried to escape, 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.[5]

See also

References

  1. ↑ Zhang MF, Wu SJ, Zhang J, Yang YJ, Tan JZ, Guan HJ, Liu Y, Tang K, Krutmann J, Xu SH, Jin L, Guan YQ, Li H, Wang SJ (20 December 2016). "Large-scale genome-wide scans do not support petaloid toenail as a Mendelian trait". Journal of Genetics and Genomics. 43 (12): 702–704. doi:10.1016/j.jgg.2016.10.003. PMID 27964859.
  2. 1 2 Haneke E (May 2016). "Double Nail of the Little Toe". Skin Appendage Disorders. 1 (4): 163–7. doi:10.1159/000443378. PMC 4908446. PMID 27386457.
  3. 1 2 Chi CC, Wang SH (August 2004). "Inherited accessory nail of the fifth toe cured by surgical matricectomy". Dermatologic Surgery. 30 (8): 1177–9. doi:10.1111/j.1524-4725.2004.30351.x. PMID 15274716. S2CID 7930781.
  4. ↑ "Definition of Matricectomy". MedicineNet. Retrieved 2018-02-27.
  5. ↑ "关于小脚趾两瓣趾甲的传说]" [Regarding the myth of the double toenail] (in Chinese).
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