Traits

Traits linked to OCA2

OCA2 melanosomal transmembrane protein

The Human Phenotype Ontology links 141 traits to OCA2, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the nervous system

Trait	How often it is seen
EEG abnormality	Very often (80–99%)
EEG with abnormally slow frequencies	Very often (80–99%)
Epilepsy	Very often (80–99%)
Global developmental delay	Very often (80–99%)
Increased appetite	Very often (80–99%)
Neurodevelopmental delay	Very often (80–99%)
Ventriculomegaly	Very often (80–99%)
Abnormal eating behavior	Often (30–79%)
Abnormal speech pattern	Often (30–79%)
Abnormal temper tantrums	Often (30–79%)
Autism	Often (30–79%)
Autism spectrum disorder	Often (30–79%)
Behavioral abnormality	Often (30–79%)
Binge and purge	Often (30–79%)
Delayed myelination	Often (30–79%)
Difficulty sleeping	Often (30–79%)
Happy demeanor	Often (30–79%)
Inappropriate laughter	Often (30–79%)
Intellectual disability, borderline	Often (30–79%)
Intellectual disability, mild	Often (30–79%)
Intellectual disability, severe	Often (30–79%)
IQ between 34 and 49	Often (30–79%)
More active than typical	Often (30–79%)
Obsessive-compulsive trait	Often (30–79%)
Occipital cortical atrophy	Often (30–79%)
Overactive lower leg reflex	Often (30–79%)
Parietal cortical atrophy	Often (30–79%)
Perisylvian polymicrogyria	Often (30–79%)
Psychosis	Often (30–79%)
Self-injurious behavior	Often (30–79%)
Short attention span	Often (30–79%)
Skin-picking	Often (30–79%)
Specific learning disability	Often (30–79%)
Speech articulation difficulties	Often (30–79%)
Tongue thrusting	Often (30–79%)
Underdevelopment of part of brain called corpus callosum	Often (30–79%)
Abnormality of balance	Sometimes (5–29%)
Abnormality of movement	Sometimes (5–29%)
Absent speech development	Sometimes (5–29%)
Ataxia	Sometimes (5–29%)
Impaired temperature sensation	Sometimes (5–29%)
Jerking	Sometimes (5–29%)
Obstructive sleep apnea	Sometimes (5–29%)
Poor speech	Sometimes (5–29%)
Recurrent hand flapping	Sometimes (5–29%)
Shortened sleep phase	Sometimes (5–29%)
Tremor	Sometimes (5–29%)
Wide based walk	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Abnormal retinal pigmentation	Often (30–79%)
Abnormality of refraction	Often (30–79%)
Abnormality of vision	Often (30–79%)
Blue eyes	Often (30–79%)
Cross-eyed	Often (30–79%)
Decreased clarity of vision	Often (30–79%)
Different colored eyes	Often (30–79%)
Extreme sensitivity of the eyes to light	Often (30–79%)
Hypoplasia of the fovea	Often (30–79%)
Involuntary, rapid, rhythmic eye movements	Often (30–79%)
Iris transillumination defect	Often (30–79%)
Light eye color	Often (30–79%)
Macular hypopigmentation	Often (30–79%)
Optic nerve misrouting	Often (30–79%)
Posterior staphyloma	Sometimes (5–29%)
Close sighted	Not recorded
Fundus hypopigmentation	Not recorded
Outward facing eye ball	Not recorded
Visual impairment	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Development of small head that was not present at birth	Very often (80–99%)
Head stopped growing	Very often (80–99%)
Almond shaped eyes	Often (30–79%)
Drooling	Often (30–79%)
Flat back of skull	Often (30–79%)
Protruding tongue	Often (30–79%)
White eyebrow	Often (30–79%)
Wide mouth	Often (30–79%)
Widely spaced teeth	Often (30–79%)
Abnormal facial shape	Sometimes (5–29%)
Big lower jaw	Sometimes (5–29%)
Downturned corners of mouth	Sometimes (5–29%)
Mild microcephaly	Sometimes (5–29%)
Thin red part of the upper lip	Sometimes (5–29%)
White eyelashes	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Central adrenal insufficiency	Often (30–79%)
Central hypothyroidism	Often (30–79%)
Decreased circulating gonadotropin concentration	Often (30–79%)
Decreased circulating T4 concentration	Often (30–79%)
Decreased response to growth hormone stimulation test	Often (30–79%)
Delayed puberty	Often (30–79%)
Hypogonadotropic hypogonadism	Often (30–79%)
Premature adrenarche	Often (30–79%)
Premature pubic hair growth	Often (30–79%)
Underdeveloped pituitary gland	Often (30–79%)
Decreased circulating inhibin B concentration	Sometimes (5–29%)
Early onset of puberty	Rarely (1–4%)

Abnormality of the integument

Trait	How often it is seen
Freckling	Often (30–79%)
Loss of hair color	Often (30–79%)
Patchy lightened skin	Often (30–79%)
White hair	Often (30–79%)
Absent skin pigmentation	Sometimes (5–29%)
Basal cell carcinoma	Sometimes (5–29%)
Cutaneous melanoma	Sometimes (5–29%)
Squamous cell carcinoma of the skin	Sometimes (5–29%)
Hyperpigmented nevi	Rarely (1–4%)
Albinism	Not recorded
Freckles in sun-exposed areas	Not recorded
Red hair	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Undescended testes	Very often (80–99%)
Decreased testicular size	Often (30–79%)
Infertility	Often (30–79%)
Primary amenorrhea	Often (30–79%)
Small clitoris	Often (30–79%)
Smaller than typical growth of scrotum	Often (30–79%)
Underdeveloped inner lips	Often (30–79%)
Underdevelopment of external reproductive organs	Often (30–79%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Decreased muscle tone in infant	Often (30–79%)
Functional motor deficit	Often (30–79%)
Low muscle tone	Often (30–79%)
Scoliosis	Often (30–79%)
Abnormal formation of the hip	Sometimes (5–29%)
Osteopenia	Sometimes (5–29%)
Osteoporosis	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties in infancy	Very often (80–99%)
Constipation	Often (30–79%)
Feeding difficulties	Often (30–79%)
Poor suck	Often (30–79%)
Delayed gastric emptying	Sometimes (5–29%)
Poor swallowing	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Short foot	Often (30–79%)
Small hand	Often (30–79%)
Fluid accumulation in lower limbs	Sometimes (5–29%)
Limitation of movement at ankles	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Obesity	Very often (80–99%)
Faltering weight	Often (30–79%)
Short stature	Often (30–79%)
Small for gestational age	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Postterm pregnancy	Often (30–79%)
Less than 10 fetal movements in 12 hours	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Diabetes mellitus	Often (30–79%)
Heat intolerance	Sometimes (5–29%)

Abnormality of the immune system

Trait	How often it is seen
Recurrent respiratory infections	Often (30–79%)

Abnormality of the respiratory system

Trait	How often it is seen
Central apnea	Sometimes (5–29%)

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 OCA2 and how often each is seen. Find out more at hpo.jax.org.

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