Anonychia-onychodystrophy with hypoplasia or absence of distal phalanges

The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.

Cooks syndrome is a malformation syndrome affecting the apical structures of digits and presenting with hypo/aplasia of nails and distal phalanges. More than half of digits are usually involved and the thumbs may appear digitalized.

To date, less than 20 individuals have been described in the world literature.

Cooks syndrome is congenital and presents with hypo/anonychia, small or absent distal phalanges and digitalization of the thumbs. Usually, the nails of digits 1-3 are progressively deformed, with anonychia congenita totalis (see this term) in the digits 4-5 and in all toes. Additional features include hypoplasia of the distal phalanges in digits 2-4 with absence of the distal phalanx of digit 5. In the feet, there is absence of all distal phalanges of digits 2-5 with hypoplasia of the distal phalanx of digit 1. Finger pads at the dorsal aspects of the affected fingers may occasionally be seen. To date, no facial dysmorphism has been associated with Cooks syndrome. Cooks syndrome is considered a clinical form of brachydactyly type B (see this term), distinct from the typical variant with sparing or duplication of the thumbs and caused by mutations in the ROR2 gene (9q22).

The exact etiology of Cooks syndrome is still unknown but microduplications on chromosome 17q24.3 and involvement of a non-coding element of the SOX9 gene (17q24.3) have recently been associated in some patients with Cooks syndrome. The SOX9 gene is necessary for chondrocyte differentiation and cartilage formation.

An autosomal dominant mode of inheritance has been proposed. Genetic counseling may be proposed and the recurrence risk is of 50%.

Visit the Orphanet disease page for more resources.

Last updated: 11/1/2014

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.