Traits

Traits linked to RTL1

retrotransposon Gag like 1

The Human Phenotype Ontology links 168 traits to RTL1, by body system: features seen in people with one of the gene's rare conditions.

RTL1

Abnormality of head or neck

Trait	How often it is seen
Abnormal facial shape	Very often (80–99%)
Abnormally large tongue	Often (30–79%)
Chin with horizontal crease	Often (30–79%)
Deep philtrum	Often (30–79%)
Depressed nasal bridge	Often (30–79%)
Hairy forehead	Often (30–79%)
Prominent forehead	Often (30–79%)
Receding chin	Often (30–79%)
Short neck	Often (30–79%)
Short opening between the eyelids	Often (30–79%)
Abnormally small head	Sometimes (5–29%)
Asymmetry of the posterior head	Sometimes (5–29%)
Bifid uvula	Sometimes (5–29%)
Big lower jaw	Sometimes (5–29%)
Broad forehead	Sometimes (5–29%)
Chin with H-shaped crease	Sometimes (5–29%)
Cleft palate	Sometimes (5–29%)
Decreased facial expression	Sometimes (5–29%)
Decreased size of maxilla	Sometimes (5–29%)
Dense bone of skull base	Sometimes (5–29%)
Downturned corners of mouth	Sometimes (5–29%)
Drooling	Sometimes (5–29%)
Exaggerated cupid's bow	Sometimes (5–29%)
Extra bones within cranial sutures	Sometimes (5–29%)
Eye folds	Sometimes (5–29%)
Frontal bossing	Sometimes (5–29%)
Full cheeks	Sometimes (5–29%)
Full lips	Sometimes (5–29%)
High palate	Sometimes (5–29%)
Little lower jaw	Sometimes (5–29%)
Long philtrum	Sometimes (5–29%)
Narrow eyelid opening	Sometimes (5–29%)
Narrow forehead	Sometimes (5–29%)
Narrow mouth	Sometimes (5–29%)
Narrow opening between the eyelids	Sometimes (5–29%)
Nasal tip, upturned	Sometimes (5–29%)
Open mouth	Sometimes (5–29%)
Prominent area between the eyebrows	Sometimes (5–29%)
Redundant neck skin	Sometimes (5–29%)
Relatively large head	Sometimes (5–29%)
Short philtrum	Sometimes (5–29%)
Tented mouth	Sometimes (5–29%)
Wide nasal bridge	Sometimes (5–29%)
Wide nose	Sometimes (5–29%)
Wider-than-typical soft spot of skull	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Short foot	Very often (80–99%)
Small hand	Very often (80–99%)
Limb undergrowth	Often (30–79%)
Abnormality of the outermost finger bone	Sometimes (5–29%)
Acromicria	Sometimes (5–29%)
Bowed shankbone	Sometimes (5–29%)
Broad outermost finger bone	Sometimes (5–29%)
Coxa valga	Sometimes (5–29%)
Curvature of digit	Sometimes (5–29%)
Curvature of middle finger	Sometimes (5–29%)
Flexion contracture of finger	Sometimes (5–29%)
Front half of foot turns inward	Sometimes (5–29%)
Interphalangeal joint contracture of finger	Sometimes (5–29%)
Inward turned thumb	Sometimes (5–29%)
Long toe	Sometimes (5–29%)
Metaphyseal spurs	Sometimes (5–29%)
Overlapping toe	Sometimes (5–29%)
Prominent heel bone	Sometimes (5–29%)
Short neck of thighbone	Sometimes (5–29%)
Short shinbone	Sometimes (5–29%)
Shortened 1st long bone of hand	Sometimes (5–29%)
Single transverse palmar crease	Sometimes (5–29%)
Small end part of innermost shankbone	Sometimes (5–29%)
Thumb contracture	Sometimes (5–29%)
Ulnar deviation of the wrist	Sometimes (5–29%)
Upper limb undergrowth	Sometimes (5–29%)
Wrist flexion contracture	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Coat hanger sign of ribs	Always
Double-Jointed	Very often (80–99%)
Low muscle tone	Very often (80–99%)
Small chest	Very often (80–99%)
Abnormality of the skeletal system	Often (30–79%)
Flexed joint that cannot be straightened	Often (30–79%)
Funnel chest	Often (30–79%)
Hypoplastic iliac wing	Often (30–79%)
Kyphoscoliosis	Often (30–79%)
Low muscle tone, in neonatal onset	Often (30–79%)
Abnormality of the costochondral junction	Sometimes (5–29%)
Absent glenoid fossa	Sometimes (5–29%)
Anterior rib cupping	Sometimes (5–29%)
Decreased muscle tone in infant	Sometimes (5–29%)
Long collarbone	Sometimes (5–29%)
Missing part of vertebrae	Sometimes (5–29%)
Narrow chest	Sometimes (5–29%)
Permanent flexion of the finger or toe	Sometimes (5–29%)
Prominent sternum	Sometimes (5–29%)
Scoliosis	Sometimes (5–29%)
Short ribs	Sometimes (5–29%)
Small shoulder blade	Sometimes (5–29%)
Small wings of the pelvic girdle	Sometimes (5–29%)
Speckled calcifications in end part of bone	Sometimes (5–29%)
Wavy ribs	Sometimes (5–29%)

Abnormality of the nervous system

Trait	How often it is seen
Delayed speech and language development	Very often (80–99%)
Global developmental delay	Very often (80–99%)
Intellectual disability, mild	Very often (80–99%)
Motor delay	Very often (80–99%)
Intellectual disability	Often (30–79%)
Autism spectrum disorder	Sometimes (5–29%)
Delayed motor skills	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Fewer or absent grooves in brain	Sometimes (5–29%)
Moderate global developmental delay	Sometimes (5–29%)
Poor eye contact	Sometimes (5–29%)
Poor fine motor coordination	Sometimes (5–29%)
Poor social interactions	Sometimes (5–29%)
Severe global developmental delay	Sometimes (5–29%)
Spinal dysraphism	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Feeding difficulties	Very often (80–99%)
Feeding difficulties in infancy	Very often (80–99%)
Gap between large left and right abdominal muscles	Often (30–79%)
Inguinal hernia	Often (30–79%)
Poor suck	Often (30–79%)
Umbilical hernia	Often (30–79%)
Belly sticks out	Sometimes (5–29%)
Enlarged liver	Sometimes (5–29%)
Gastrostomy tube feeding in infancy	Sometimes (5–29%)
Hepatoblastoma	Sometimes (5–29%)
Hernia of the abdominal wall	Sometimes (5–29%)
Omphalocele	Sometimes (5–29%)
Pyloric stenosis	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Abnormal aortic arch morphology	Sometimes (5–29%)
Abnormality of the heart	Sometimes (5–29%)
An opening in the wall separating the top two chambers of the heart	Sometimes (5–29%)
Avascular peripheral retina	Sometimes (5–29%)
Enlarged and thickened heart muscle	Sometimes (5–29%)
Enlarged liver and spleen	Sometimes (5–29%)
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)
Increased blood pressure in blood vessels of lungs	Sometimes (5–29%)
Narrowing of lung artery	Sometimes (5–29%)

Growth abnormality

Trait	How often it is seen
Growth delay as children	Very often (80–99%)
Prenatal growth deficiency	Very often (80–99%)
Birth weight > 90th percentile	Often (30–79%)
Growth delay	Often (30–79%)
Obesity	Often (30–79%)
Short stature	Often (30–79%)
Small for gestational age	Often (30–79%)
Truncal obesity	Often (30–79%)
General overgrowth	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Abnormality of the genitourinary system	Sometimes (5–29%)
Hydronephrosis	Sometimes (5–29%)
Underdevelopment of external reproductive organs	Sometimes (5–29%)
Undescended testes	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Respiratory failure	Often (30–79%)
Poorly developed lungs	Sometimes (5–29%)
Softening of voice box tissue	Sometimes (5–29%)
Stiff lung or chest wall causing decreased lung volume	Sometimes (5–29%)

Abnormality of prenatal development or birth

Trait	How often it is seen
High levels of amniotic fluid	Very often (80–99%)
Large placenta	Very often (80–99%)
Premature birth	Often (30–79%)

Abnormality of the breast

Trait	How often it is seen
Inverted nipples	Sometimes (5–29%)
Small nipples	Sometimes (5–29%)
Wide-spaced nipples	Sometimes (5–29%)

Abnormality of the ear

Trait	How often it is seen
Small ears	Often (30–79%)
Ears rotated toward back of head	Sometimes (5–29%)
Recurrent middle ear infection	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Deeply set eye	Sometimes (5–29%)
Inward turning cross eyed	Sometimes (5–29%)

Abnormality of the integument

Trait	How often it is seen
Hanging skin	Sometimes (5–29%)
Small nail	Sometimes (5–29%)

Laboratory abnormality

Trait	How often it is seen
Elevated serum cholesterol	Sometimes (5–29%)
Maturity-onset diabetes of the young	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Early onset of puberty	Very often (80–99%)

Abnormality of the voice

Trait	How often it is seen
Hoarse cry	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 RTL1 and how often each is seen. Find out more at hpo.jax.org.

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