What is (are) Anonychia congenita ?
Anonychia congenita is an extremely rare nail disorder characterized by the complete absence (anonychia) or abnormally developed  fingernails and toenails. Affected individuals usually do not have hair, teeth, or bone abnormalities. Signs and symptoms are variable, even among affected members of the same family. Less than 20 individuals with anonychia congenita have been identified. This condition is thought to be caused by mutations in the RSPO4 gene and inherited in an autosomal recessive fashion.