Rare Pulmonology News

Disease Profile

Anonychia-onychodystrophy with hypoplasia or absence of distal phalanges

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.

<1 >

US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

Anonychia and absence/hypoplasia of distal phalanges; Cooks syndrome


Congenital and Genetic Diseases; Musculoskeletal Diseases; Skin Diseases


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

Orpha Number: 1487

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.

Clinical description
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.

Genetic counseling
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.


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
80%-99% of people have these symptoms
Aplastic/hypoplastic toenail
Absent/small toenails
Absent/underdeveloped toenails

[ more ]

Short fingers or toes
Broad thumb
Broad thumbs
Wide/broad thumb

[ more ]

Dystrophic fingernails
Poor fingernail formation
Dystrophic toenail
Poor toenail formation
Split hand
Claw hand
Claw hand deformities
Claw hands
Claw-hand deformities

[ more ]

Triphalangeal thumb
Finger-like thumb
Percent of people who have these symptoms is not available through HPO
Absent nails
Aplastic nails

[ more ]

Autosomal dominant inheritance
Complete duplication of thumb phalanx
Complete duplication of thumb bones
Downslanted palpebral fissures
Downward slanting of the opening between the eyelids
High palate
Elevated palate
Increased palatal height

[ more ]

Nail dysplasia
Atypical nail growth
Nail dystrophy
Poor nail formation
Prominent nasal bridge
Elevated nasal bridge
High nasal bridge
Prominent bridge of nose
Prominent nasal root
Protruding bridge of nose
Protruding nasal bridge

[ more ]

Prominent nose
Big nose
Disproportionately large nose
Increased nasal size
Increased size of nose
Large nose
Pronounced nose

[ more ]

Short 5th finger
Short fifth finger
Short fifth fingers
Short little finger
Short pinkie finger
Short pinky finger

[ more ]

Short philtrum
Shortening of all distal phalanges of the fingers
Shortening of all outermost bones of the fingers
Shortening of all distal phalanges of the toes
Shortening of all outermost bone of the toes
Underdeveloped nasal alae
Underdeveloped tissue around nostril

Learn more

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.

In-Depth Information

  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Anonychia-onychodystrophy with hypoplasia or absence of distal phalanges. Click on the link to view a sample search on this topic.