Congenital onychodysplasia of the index fingers is defined by the presence of the condition at birth, either unilateral or bilateral index finger involvement, variable distortion of the nail or lunula, and polyonychia, micronychia, anonychia, hemi-onychogryphosis, or malalignment.[1]
This condition is also called Iso-Kikuchi syndrome, since Iso was the first author who published it in a Japanese paper.[2]
It is still unknown what exactly causes congenital onychodystrophy of the index finger. Nonetheless, there is evidence in favor of hereditary transmission.[3]
Milani-Nejad, Nima; Mosser-Goldfarb, Joy (2020). "Congenital Onychodysplasia of Index Fingers: Iso-Kikuchi Syndrome". The Journal of Pediatrics. 218. Elsevier BV: 254–254.e1. doi:10.1016/j.jpeds.2019.10.008. ISSN0022-3476.
YOUN, S.H.; KWON, O.S.; PARK, K.C.; YOUN, J.I.; CHUNG, J.H. (1996). "Congenital onychodysplasia of the index fingers - Iso-Kikuchi syndrome. A case involving the second toenail". Clinical and Experimental Dermatology. 21 (6). Oxford University Press (OUP): 457–458. doi:10.1111/j.1365-2230.1996.tb00157.x. ISSN0307-6938.
