Anonychia congenita is a condition that affects the fingernails and toenails. Individuals with this condition are typically missing all of their fingernails and toenails (anonychia). This absence of nails is noticeable from birth (congenital). In some cases, only part of the nail is missing (hyponychia) or not all fingers and toes are affected. All of the other tissues at the tips of the fingers and toes, including structures that usually support the nail and its growth (such as the nail bed), are normal.

Mutations in the RSPO4 gene cause anonychia congenita. The RSPO4 gene provides instructions for making a protein called R-spondin-4. R-spondin-4 plays a role in the Wnt signaling pathway, a series of steps that affect the way cells and tissues develop. Wnt signaling is important for cell division, attachment of cells to one another (adhesion), cell movement (migration), and many other cellular activities. During early development, Wnt signaling plays a critical role in the growth and development of nails. R-spondin-4 is active in the skeleton and contributes to limb formation, particularly at the ends of the fingers and toes where nail development occurs.

Anonychia congenita is a rare condition; its prevalence is unknown.

Anonychia congenita resulting from RSPO4 gene mutations is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.

Published Date: May 01, 2017Published By: National Institutes of Health