Traits

Traits linked to RRM2B

ribonucleotide reductase regulatory TP53 inducible subunit M2B

The Human Phenotype Ontology links 181 traits to RRM2B, by body system: features seen in people with one of the gene's rare conditions.

RRM2B

Abnormality of the nervous system

Trait	How often it is seen
Leukoencephalopathy	Very often (80–99%)
Nerve damage causing decreased feeling and movement	Very often (80–99%)
Abnormal cerebral white matter morphology	Often (30–79%)
Ataxia	Often (30–79%)
Decreased motor nerve conduction velocity	Often (30–79%)
Decreased number of large peripheral myelinated nerve fibers	Often (30–79%)
Decreased sensory nerve conduction velocity	Often (30–79%)
Demyelinating peripheral neuropathy	Often (30–79%)
Difficulty articulating speech	Often (30–79%)
Diminished deep tendon reflex	Often (30–79%)
Peripheral axonal neuropathy	Often (30–79%)
Peripheral neuropathy	Often (30–79%)
Pins and needles feeling	Often (30–79%)
Resting tremor	Often (30–79%)
Slow movements	Often (30–79%)
Abnormal gait	Sometimes (5–29%)
Abnormal pyramidal sign	Sometimes (5–29%)
Abnormal spinocerebellar tract morphology	Sometimes (5–29%)
Abnormality of balance	Sometimes (5–29%)
Abnormality of extrapyramidal motor function	Sometimes (5–29%)
Anxiety	Sometimes (5–29%)
Cognitive impairment	Sometimes (5–29%)
Decreased muscle movement	Sometimes (5–29%)
Decreased reflex response	Sometimes (5–29%)
Deficit in phonologic short-term memory	Sometimes (5–29%)
Degeneration of cerebellum	Sometimes (5–29%)
Delayed speech and language development	Sometimes (5–29%)
Dementia	Sometimes (5–29%)
Depression	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Focal white matter lesions	Sometimes (5–29%)
Inability to coordinate movements when walking	Sometimes (5–29%)
Intellectual disability	Sometimes (5–29%)
Lethargy	Sometimes (5–29%)
Loss of ability to walk	Sometimes (5–29%)
Migraine	Sometimes (5–29%)
Paralysis or weakness of one side of body	Sometimes (5–29%)
Psychomotor deterioration	Sometimes (5–29%)
Repeated seizures without recovery between them	Sometimes (5–29%)
Tremor	Sometimes (5–29%)
Uncoordinated limb movement	Sometimes (5–29%)
Bipolar disorder	Rarely (1–4%)
Worsening neurological symptoms	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone in trunk	Always
Cytochrome C oxidase-negative muscle fibers	Often (30–79%)
Decreased lung function due to weak breathing muscles	Often (30–79%)
Difficulty walking up stairs	Often (30–79%)
EMG abnormality	Often (30–79%)
EMG: myopathic abnormalities	Often (30–79%)
Fatigable weakness of respiratory muscles	Often (30–79%)
Low muscle tone	Often (30–79%)
Mitochondrial myopathy	Often (30–79%)
Muscle degeneration	Often (30–79%)
Muscle tissue disease	Often (30–79%)
Progressive intervertebral space narrowing	Often (30–79%)
Ragged-red muscle fibers	Often (30–79%)
Tired easily	Often (30–79%)
Weak and soft bones	Often (30–79%)
Weakness of outermost muscles	Often (30–79%)
Cogwheel rigidity	Sometimes (5–29%)
Decreased muscle mass	Sometimes (5–29%)
Delayed bone maturation	Sometimes (5–29%)
Frequent falls	Sometimes (5–29%)
Generalized decreased muscle tone	Sometimes (5–29%)
Muscle weakness	Sometimes (5–29%)
Neck flexion weakness	Sometimes (5–29%)
Neck muscle weakness	Sometimes (5–29%)
Recurrent fractures	Sometimes (5–29%)
Rigidity	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Muscle spasm	Rarely (1–4%)
Osteoporosis	Rarely (1–4%)
Spasticity and rigidity of muscles	Rarely (1–4%)
Increased muscle fatiguability	Not recorded

Abnormality of the eye

Trait	How often it is seen
Progressive external ophthalmoplegia	Always
Rod-cone dystrophy	Always
Visual impairment	Always
Drooping upper eyelid	Very often (80–99%)
Paralysis or weakness of muscles within or surrounding outer part of eye	Very often (80–99%)
Pigmentary retinopathy	Very often (80–99%)
Abnormality of eye movement	Often (30–79%)
Drooping of both upper eyelids	Often (30–79%)
Eye muscle paralysis	Often (30–79%)
Weakness of muscles controlling eye movement	Often (30–79%)
Clouding of the lens of the eye	Sometimes (5–29%)
Glaucoma	Sometimes (5–29%)
Inward turning cross eyed	Sometimes (5–29%)
Loss of peripheral vision	Sometimes (5–29%)
Optic atrophy	Sometimes (5–29%)
Optic disc pallor	Sometimes (5–29%)
Spicular pigmentation of the retina	Sometimes (5–29%)
Cerebral visual impairment	Rarely (1–4%)

Abnormality of the digestive system

Trait	How often it is seen
Abdominal bloating	Very often (80–99%)
Abdominal pain	Very often (80–99%)
Acid reflux	Very often (80–99%)
Atrophic muscularis propria	Very often (80–99%)
Gastrointestinal dysmotility	Very often (80–99%)
Nausea	Very often (80–99%)
Poor appetite	Very often (80–99%)
Poor swallowing	Very often (80–99%)
Small intestinal dysmotility	Very often (80–99%)
Vomiting	Very often (80–99%)
Abnormality of the gastrointestinal tract	Often (30–79%)
Diarrhea	Often (30–79%)
Feeding difficulties	Often (30–79%)
Constipation	Sometimes (5–29%)
Delayed gastric emptying	Sometimes (5–29%)
Scar tissue replaces healthy tissue in the liver	Sometimes (5–29%)
Abnormality of the liver	Rarely (1–4%)

Laboratory abnormality

Trait	How often it is seen
Increased lactate in body	Always
Renal Fanconi syndrome	Always
High liver enzymes	Often (30–79%)
Increased blood alanine	Often (30–79%)
Increased CSF protein concentration	Often (30–79%)
Accumulation of acid in body due to kidney problem	Sometimes (5–29%)
Diabetes mellitus	Sometimes (5–29%)
Elevated blood creatine phosphokinase	Sometimes (5–29%)
Glucose in urine	Sometimes (5–29%)
Glucose intolerance	Sometimes (5–29%)
Higher than normal levels of lactate in blood	Sometimes (5–29%)
Increased CSF lactate	Sometimes (5–29%)
Macrovesicular hepatic steatosis	Sometimes (5–29%)
Severe lactic acidosis	Sometimes (5–29%)
Fluid retention	Rarely (1–4%)
High levels of ketone bodies	Rarely (1–4%)
Abnormal urinary amino-acid findings	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Complete heart block	Very often (80–99%)
Abnormal atrioventricular conduction	Sometimes (5–29%)
Abnormal heart rate	Sometimes (5–29%)
Disease of the heart muscle	Sometimes (5–29%)
Left ventricular hypertrophy	Sometimes (5–29%)
Quivering upper heart chambers resulting in irregular heartbeat	Sometimes (5–29%)
Reduced left ventricular ejection fraction	Sometimes (5–29%)
Stretched and thinned heart muscle	Sometimes (5–29%)
Ventricular arrhythmia	Sometimes (5–29%)
Palpitations	Rarely (1–4%)

Abnormality of the endocrine system

Trait	How often it is seen
Anterior hypopituitarism	Often (30–79%)
Decreased parathyroid hormone secretion	Sometimes (5–29%)
Delayed puberty	Sometimes (5–29%)
Hypergonadotropic hypogonadism	Sometimes (5–29%)
Hypogonadotropic hypogonadism	Sometimes (5–29%)
Enlarged thyroid gland in neck	Rarely (1–4%)
Overactive thyroid	Rarely (1–4%)
Underactive thyroid	Rarely (1–4%)

Abnormality of limbs

Trait	How often it is seen
Limb muscle weakness	Very often (80–99%)
Abnormality of the hand	Often (30–79%)
Areflexia of lower limbs	Often (30–79%)
Foot drop	Often (30–79%)
Quadriceps weakness	Often (30–79%)
Weak shoulder muscles	Often (30–79%)
Absent ankle reflexes	Rarely (1–4%)

Abnormality of head or neck

Trait	How often it is seen
Abnormality of the extraocular muscles	Often (30–79%)
Bell's palsy	Often (30–79%)
Decreased facial expressions	Often (30–79%)
High palate	Often (30–79%)
Weakness of facial musculature	Often (30–79%)
Facial diplegia	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Abnormality of the mitochondrion	Often (30–79%)
Abnormal cell morphology	Sometimes (5–29%)
Decreased activity of mitochondrial complex IV	Sometimes (5–29%)
Multiple mitochondrial DNA deletions	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Proximal tubulopathy	Always
Stage 5 chronic kidney disease	Often (30–79%)
Chronic kidney disease	Sometimes (5–29%)
Nocturia	Rarely (1–4%)

Constitutional symptom

Trait	How often it is seen
Decreased ability to exercise	Very often (80–99%)
Exercise-induced muscle pain	Often (30–79%)
Fatigue	Often (30–79%)
Muscle ache	Often (30–79%)

Growth abnormality

Trait	How often it is seen
Wasting syndrome	Very often (80–99%)
Weight loss	Often (30–79%)
Faltering weight	Sometimes (5–29%)
Short stature	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Hearing impairment	Often (30–79%)
Sensorineural hearing impairment	Often (30–79%)
Bilateral sensorineural hearing impairment	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Breathing difficulties	Sometimes (5–29%)
Exertional breathlessness	Sometimes (5–29%)
Respiratory function loss	Sometimes (5–29%)

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 voice

Trait	How often it is seen
Inability to produce voice sounds	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 RRM2B and how often each is seen. Find out more at hpo.jax.org.

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