Traits

Traits linked to PHF21A

PHD finger protein 21A

The Human Phenotype Ontology links 35 traits to PHF21A, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of head or neck

Trait	How often it is seen
Broad head shape	Very often (80–99%)
Broad nasal tip	Very often (80–99%)
Decreased bone formation of skull	Very often (80–99%)
Depressed nasal tip	Very often (80–99%)
Eye folds	Very often (80–99%)
Little lower jaw	Very often (80–99%)
Prominent nasal bridge	Very often (80–99%)
Underdeveloped tissue around nostril	Very often (80–99%)
Downturned corners of mouth	Often (30–79%)
Holes in parietal bones	Often (30–79%)
Short philtrum	Often (30–79%)
Asymmetry of the posterior head	Sometimes (5–29%)
Big calvaria	Sometimes (5–29%)
Abnormal facial shape	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Delayed speech and language development	Always
Global developmental delay	Always
Intellectual disability	Always
Anxiety	Very often (80–99%)
Attention deficit	Very often (80–99%)
Autism spectrum disorder	Often (30–79%)
Epilepsy	Often (30–79%)

Abnormality of limbs

Trait	How often it is seen
Curvature of little finger	Often (30–79%)
Tapered finger	Often (30–79%)
Webbed fingers or toes	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Delayed puberty	Sometimes (5–29%)
Underactive thyroid	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Cross-eyed	Often (30–79%)
Involuntary, rapid, rhythmic eye movements	Often (30–79%)

Abnormality of the genitourinary system

Trait	How often it is seen
Short penis	Often (30–79%)
Nephroblastoma	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Formation of new noncancerous bone on top of existing bone	Very often (80–99%)
Generalized decreased muscle tone	Often (30–79%)

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Low number of red blood cells or hemoglobin	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
High blood pressure	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Obesity	Often (30–79%)

How often is among people with one of the gene's conditions, the most often across them, as the Human Phenotype Ontology records it. These pages describe traits and the research behind them; they are not a diagnosis, and a doctor or genetic counsellor is the person to ask about symptoms.

Where this comes from

The Human Phenotype Ontology, release 2026-09-01: the traits linked to PHF21A and how often each is seen. Find out more at hpo.jax.org.

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