Clinodactyly is a medical term describing a bend or curvature of the fifth fingers (the "little fingers") toward the adjacent fourth fingers. It is a fairly common isolated anomaly which often goes unnoticed, but also occurs in combination with other abnormalities in many geneticsyndromes, such as Russell-Silver syndrome, Feingold syndrome and in approximately 80% of individuals with Down syndrome. When identified in prenatal ultrasound, it is considered statistically correlated with increased risk of chromosome aberration in the fetus and may be an indication for intrauterine sampling for fetal chromosome analysis.
The term can also be used to describe curled toes. Clinodactyly or congenital curly toes, is sometimes seen in the third, fourth or fifth toe and is "fairly common and follows a familial pattern." 
^Fuente: Series de porcentajes obtenidas en un amplio estudio realizado por el CMD (Centro Médico Down) de la Fundación Catalana del Síndrome de Down, sobre 796 personas con SD. Estudio completo en Josep M. Corretger et al (2005). Síndrome de Down: Aspectos médicos actuales. Ed. Masson, para la Fundación Catalana del Síndrome de Down. ISBN 84-458-1504-0. Pag. 24-32.
^Koepsel, Kirk A. "Curled Toes". PodiatryNetwork.com. Retrieved December 2010.