Traits

Traits linked to DNA2

DNA replication helicase/nuclease 2

The Human Phenotype Ontology links 94 traits to DNA2, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the musculoskeletal system

Trait	How often it is seen
Delayed bone maturation	Always
Flattened vertebrae	Always
Abnormal formation of the hip	Often (30–79%)
Cone-shaped end part of bone	Often (30–79%)
Double-Jointed	Often (30–79%)
Generalized decreased muscle tone	Often (30–79%)
Gowers sign	Often (30–79%)
Kyphoscoliosis	Often (30–79%)
Mitochondrial myopathy	Often (30–79%)
Multiple joint contractures	Often (30–79%)
Muscle spasm	Often (30–79%)
Muscle tissue disease	Often (30–79%)
Osteopenia	Often (30–79%)
Prominent swayback	Often (30–79%)
Difficulty walking up stairs	Sometimes (5–29%)
Diffuse skeletal muscle wasting	Sometimes (5–29%)
Muscle weakness	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Abnormally small head	Always
Beaked nose	Always
Depressed nasal bridge	Always
Frontal bossing	Always
Little lower jaw	Always
Sparse eyebrow	Always
Sparse scalp hair	Always
Deformity of the skull	Very often (80–99%)
Narrow face	Very often (80–99%)
Abnormal tooth enamel	Often (30–79%)
Decreased facial expression	Often (30–79%)
Decreased number of teeth	Often (30–79%)
Downward slanting of the opening between the eyelids	Often (30–79%)
Delayed eruption of teeth	Sometimes (5–29%)
Empty sella turcica	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Clouding of the lens of the eye	Always
Decreased clarity of vision	Always
Progressive external ophthalmoplegia	Always
Abnormally small eyeball	Often (30–79%)
Congenital drooping upper eyelid	Often (30–79%)
Corneal opacity	Often (30–79%)
Deeply set eye	Often (30–79%)
Drooping upper eyelid	Often (30–79%)
Glaucoma	Often (30–79%)
Optic atrophy	Sometimes (5–29%)
Peters anomaly	Sometimes (5–29%)
Weakness of muscles controlling eye movement	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Abnormal gait	Always
Global developmental delay	Always
Intellectual disability	Always
Cognitive impairment	Very often (80–99%)
Mild global developmental delay	Very often (80–99%)
Depression	Often (30–79%)
Obstructive sleep apnea	Often (30–79%)
Pressure on spinal cord	Often (30–79%)
Falls	Sometimes (5–29%)
Hippocampal malrotation	Sometimes (5–29%)
Underdevelopment of part of brain called corpus callosum	Sometimes (5–29%)
Ventriculomegaly	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Flared wide portion of long bone	Always
Shortened long bone of hand	Always
Curvature of little finger	Very often (80–99%)
Gap between 1st and 2nd toes	Very often (80–99%)
Limb-girdle muscle weakness	Very often (80–99%)
Pelvic girdle muscle weakness	Often (30–79%)
Short finger bones	Often (30–79%)
Weak shoulder muscles	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Decreased body weight	Always
Prenatal growth deficiency	Always
Short stature	Always
Small for gestational age	Very often (80–99%)
Wasting syndrome	Very often (80–99%)
Slender build	Often (30–79%)

Abnormality of the integument

Trait	How often it is seen
Photosensitive skin	Always
Poikiloderma	Always
Poor nail formation	Very often (80–99%)
Prematurely aged appearance	Very often (80–99%)
Abnormal blistering of the skin	Often (30–79%)

Abnormality of the endocrine system

Trait	How often it is seen
Decreased circulating insulin-like growth factor 1 concentration	Always
Reduced circulating growth hormone concentration	Always
Underactive thyroid	Very often (80–99%)

Abnormality of the genitourinary system

Trait	How often it is seen
Short penis	Always
Abnormal kidney location	Often (30–79%)
Undescended testes	Often (30–79%)

Abnormal cellular phenotype

Trait	How often it is seen
Multiple mitochondrial DNA deletions	Always
Decreased mitochondrial number	Often (30–79%)

Abnormality of the ear

Trait	How often it is seen
Abnormal earlobe	Often (30–79%)
Absent earlobe	Often (30–79%)

Abnormality of the respiratory system

Trait	How often it is seen
Exertional breathlessness	Often (30–79%)
Breathing difficulty	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Muscle ache	Often (30–79%)
Decreased ability to exercise	Not recorded

Laboratory abnormality

Trait	How often it is seen
Elevated creatine kinase after exercise	Often (30–79%)
Elevated blood creatine phosphokinase	Sometimes (5–29%)

Abnormality of prenatal development or birth

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

Abnormality of the cardiovascular system

Trait	How often it is seen
Patent foramen ovale	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 DNA2 and how often each is seen. Find out more at hpo.jax.org.

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