Traits

Traits linked to RYR1

ryanodine receptor 1

The Human Phenotype Ontology links 213 traits to RYR1, 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
Central core regions in muscle fibers	Always
Centrally nucleated skeletal muscle fibers	Always
Generalized muscle weakness	Always
Increased variability in muscle fiber diameter	Always
Kyphoscoliosis	Always
Low muscle tone, in neonatal onset	Always
Minicore myopathy	Always
Muscle degeneration	Always
Muscle fiber degeneration	Always
Muscle weakness	Always
Proximal neurogenic muscle weakness	Always
Scoliosis	Always
Thoracic kyphosis	Always
Excessive inward curvature of lower spine	Very often (80–99%)
Fatigable weakness	Very often (80–99%)
Generalized decreased muscle tone	Very often (80–99%)
Low muscle tone	Very often (80–99%)
Abnormally shaped muscle	Often (30–79%)
Axial muscle weakness	Often (30–79%)
Difficulty running	Often (30–79%)
Difficulty walking up stairs	Often (30–79%)
Diffuse skeletal muscle wasting	Often (30–79%)
Double-Jointed	Often (30–79%)
EMG: myopathic abnormalities	Often (30–79%)
Gowers sign	Often (30–79%)
Hypertrophied muscle fibers	Often (30–79%)
Increased connective tissue	Often (30–79%)
Intermittent painful muscle spasms	Often (30–79%)
Internally nucleated skeletal muscle fibers	Often (30–79%)
Low muscle tone in trunk	Often (30–79%)
Multiple joint contractures	Often (30–79%)
Muscle stiffness	Often (30–79%)
Muscle tissue disease	Often (30–79%)
Muscular dystrophy	Often (30–79%)
Progressive muscle weakness	Often (30–79%)
Thin ribs	Often (30–79%)
Tired easily	Often (30–79%)
Type 1 muscle fiber atrophy	Often (30–79%)
Type 1 muscle fiber predominance	Often (30–79%)
Acute rhabdomyolysis	Sometimes (5–29%)
Decreased lung function due to weak breathing muscles	Sometimes (5–29%)
EMG: decremental response of compound muscle action potential to repetitive nerve stimulation	Sometimes (5–29%)
Exercise-induced muscle cramps	Sometimes (5–29%)
Exercise-induced rhabdomyolysis	Sometimes (5–29%)
Flexed joint that cannot be straightened	Sometimes (5–29%)
Frog-leg posture	Sometimes (5–29%)
Necrotizing myopathy	Sometimes (5–29%)
Prominent swayback	Sometimes (5–29%)
Sternocleidomastoid amyotrophy	Sometimes (5–29%)
Tibialis anterior muscle atrophy	Sometimes (5–29%)
Breakdown of skeletal muscle	Rarely (1–4%)
Rigidity	Not recorded
Type 1 and type 2 muscle fiber minicore regions	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Broad nasal tip	Always
Deep philtrum	Always
High palate	Always
Low hanging columella	Always
Midface retrusion	Always
Myopathic facies	Always
Scaphocephaly	Always
Weakness of facial musculature	Always
Eye folds	Very often (80–99%)
Narrow forehead	Very often (80–99%)
Bell's palsy	Often (30–79%)
Big head present at birth	Often (30–79%)
Downward slanting of the opening between the eyelids	Often (30–79%)
Receding chin	Often (30–79%)
Short neck	Often (30–79%)
Webbed neck	Often (30–79%)
Abnormal facial shape	Sometimes (5–29%)
Abnormality of masseter muscle	Sometimes (5–29%)
Bifid uvula	Sometimes (5–29%)
Facial diplegia	Sometimes (5–29%)
Long face	Sometimes (5–29%)
Long, narrow head	Sometimes (5–29%)
Narrow face	Sometimes (5–29%)
Narrow mouth	Sometimes (5–29%)
Prominent forehead	Sometimes (5–29%)
Tented mouth	Sometimes (5–29%)
Wide nasal bridge	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Abnormal foot muscles	Often (30–79%)
Ankle flexion contracture	Often (30–79%)
Club feet	Often (30–79%)
Dislocated hip since birth	Often (30–79%)
Distal upper limb muscle weakness	Often (30–79%)
Dropped arches	Often (30–79%)
Hyporeflexia of upper limbs	Often (30–79%)
Intrinsic hand muscle atrophy	Often (30–79%)
Pelvic girdle muscle weakness	Often (30–79%)
Proximal lower limb muscle weakness	Often (30–79%)
Proximal upper limb muscle weakness	Often (30–79%)
Winged shoulder blade	Often (30–79%)
Areflexia of lower limbs	Sometimes (5–29%)
High-arched foot	Sometimes (5–29%)
Hip contracture	Sometimes (5–29%)
Increased size of calf muscles	Sometimes (5–29%)
Knee dislocation	Sometimes (5–29%)
Long fingers	Sometimes (5–29%)
Rectus femoris muscle atrophy	Sometimes (5–29%)
Recurrent patellar dislocation	Sometimes (5–29%)
Talipes	Sometimes (5–29%)
Weak shoulder muscles	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Delayed ability to walk	Always
Motor delay	Always
Abnormality of the nervous system	Very often (80–99%)
Decreased reflex response	Very often (80–99%)
Abnormal gait	Often (30–79%)
Absent reflexes	Often (30–79%)
Delayed motor skills	Often (30–79%)
Headache	Often (30–79%)
Twitching	Often (30–79%)
Waddling gait	Often (30–79%)
Ataxia	Sometimes (5–29%)
Bulbar signs	Sometimes (5–29%)
Confusion	Sometimes (5–29%)
Delayed speech and language development	Sometimes (5–29%)
Delirium	Sometimes (5–29%)
Difficulty articulating speech	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Intellectual disability, mild	Sometimes (5–29%)
Lethargy	Sometimes (5–29%)
Muscle twitch	Sometimes (5–29%)
Peripheral axonal neuropathy	Sometimes (5–29%)
Hepatic encephalopathy	Rarely (1–4%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Hole in heart wall separating two lower heart chambers	Always
Abnormal pulse pressure	Often (30–79%)
Mitral valve prolapse	Often (30–79%)
Sinus tachycardia	Often (30–79%)
Supraventricular tachycardia	Often (30–79%)
Ventricular tachycardia	Often (30–79%)
Abnormal heart valve morphology	Sometimes (5–29%)
Abnormal T-wave	Sometimes (5–29%)
Collection of dilated blood vessels that forms mass	Sometimes (5–29%)
Extra heart beat	Sometimes (5–29%)
High-output congestive heart failure	Sometimes (5–29%)
Left ventricular hypertrophy	Sometimes (5–29%)
Low blood pressure	Sometimes (5–29%)
Prolonged QT interval	Sometimes (5–29%)
ST segment depression	Sometimes (5–29%)
Elevated heart rate	Not recorded

Laboratory abnormality

Trait	How often it is seen
Malignant hyperthermia	Very often (80–99%)
Elevated blood creatine phosphokinase	Often (30–79%)
Fever	Often (30–79%)
High blood phosphate levels	Often (30–79%)
Metabolic acidosis	Often (30–79%)
Mildly elevated creatine kinase	Often (30–79%)
Abnormal levels of creatine kinase in blood	Sometimes (5–29%)
Elevated creatine kinase after exercise	Sometimes (5–29%)
Fluid retention	Sometimes (5–29%)
Increased circulating potassium concentration	Sometimes (5–29%)
Increased lactate in body	Sometimes (5–29%)
Low blood calcium levels	Sometimes (5–29%)
Myoglobinuria	Sometimes (5–29%)
Hydrops fetalis	Not recorded
Mixed respiratory and metabolic acidosis	Not recorded

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory function loss	Always
Functional respiratory abnormality	Often (30–79%)
High blood carbon dioxide level	Often (30–79%)
Increased respiratory rate or depth of breathing	Often (30–79%)
Crackles	Sometimes (5–29%)
Neonatal asphyxia	Sometimes (5–29%)
Reduced carbon dioxide in the blood	Sometimes (5–29%)
Respiratory failure	Sometimes (5–29%)
Neonatal respiratory distress	Rarely (1–4%)
Poorly developed lungs	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Always
Feeding difficulties in infancy	Often (30–79%)
Nausea	Often (30–79%)
Acute liver failure	Sometimes (5–29%)
Decreased liver function	Sometimes (5–29%)
Pyloric stenosis	Sometimes (5–29%)
Vomiting	Sometimes (5–29%)
Liver failure	Rarely (1–4%)

Abnormality of the genitourinary system

Trait	How often it is seen
Bilateral cryptorchidism	Always
Undescended testes	Often (30–79%)
Acute kidney injury	Sometimes (5–29%)
Loss of bladder control	Sometimes (5–29%)
Oliguria	Sometimes (5–29%)
Short penis	Sometimes (5–29%)
Smaller than typical growth of scrotum	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Drooping of both upper eyelids	Always
Drooping upper eyelid	Very often (80–99%)
Wide-set eyes	Very often (80–99%)
Paralysis or weakness of muscles within or surrounding outer part of eye	Often (30–79%)
Eye muscle paralysis	Sometimes (5–29%)
Weakness of muscles controlling eye movement	Sometimes (5–29%)

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Abnormality of the coagulation cascade	Sometimes (5–29%)
Bleeding tendency	Sometimes (5–29%)
Disseminated intravascular coagulation	Rarely (1–4%)
Low platelet count	Rarely (1–4%)

Abnormality of prenatal development or birth

Trait	How often it is seen
Feet or buttocks of fetus positioned near opening of uterus	Always
Less than 10 fetal movements in 12 hours	Always
High levels of amniotic fluid	Often (30–79%)
Fetal akinesia sequence	Rarely (1–4%)

Abnormality of the integument

Trait	How often it is seen
Thickened skin	Often (30–79%)
Flushing	Sometimes (5–29%)
Dry skin	Rarely (1–4%)
Lack of sweating	Rarely (1–4%)

Growth abnormality

Trait	How often it is seen
Faltering weight	Always
Birth weight > 90th percentile	Often (30–79%)
Short stature	Often (30–79%)
Severe growth delay in children	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Dizziness	Often (30–79%)
Low-set ears	Often (30–79%)
Prominent ear	Sometimes (5–29%)

Abnormal cellular phenotype

Trait	How often it is seen
Nemaline bodies	Always
Cardiomyocyte mitochondrial proliferation	Often (30–79%)

Abnormality of the immune system

Trait	How often it is seen
Recurrent respiratory infections	Often (30–79%)
Pneumonia	Sometimes (5–29%)

Abnormality of the voice

Trait	How often it is seen
Weak cry	Often (30–79%)
Inability to produce voice sounds	Sometimes (5–29%)

Constitutional symptom

Trait	How often it is seen
Fatigue	Often (30–79%)
Exercise-induced muscle pain	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 RYR1 and how often each is seen. Find out more at hpo.jax.org.

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