Traits

Traits linked to MID1

midline 1

The Human Phenotype Ontology links 94 traits to MID1, by body system: features seen in people with one of the gene's rare conditions.

MID1

Abnormality of head or neck

Trait	How often it is seen
Corners of eye widely separated	Always
Long philtrum	Very often (80–99%)
Prominent forehead	Very often (80–99%)
Wide nasal bridge	Very often (80–99%)
Abnormal facial shape	Often (30–79%)
Cleft lip	Often (30–79%)
Cleft palate	Often (30–79%)
Nasal tip, upturned	Often (30–79%)
Widow's peak	Often (30–79%)
Abnormally small head	Sometimes (5–29%)
Cleft upper lip	Sometimes (5–29%)
Dandy-Walker malformation	Sometimes (5–29%)
Deformity of the skull	Sometimes (5–29%)
Downward slanting of the opening between the eyelids	Sometimes (5–29%)
High palate	Sometimes (5–29%)
Little lower jaw	Sometimes (5–29%)
One sided cleft upper lip	Sometimes (5–29%)
Only one upper front tooth	Sometimes (5–29%)
Pit in front of the ear	Sometimes (5–29%)
Prominent metopic ridge	Sometimes (5–29%)
Smooth philtrum	Sometimes (5–29%)
Wide fontanelles	Sometimes (5–29%)
Wider-than-typical soft spot of skull	Sometimes (5–29%)
Born with teeth	Rarely (1–4%)
Failure of development of between one and six teeth	Rarely (1–4%)
Tongue tied	Rarely (1–4%)
Abnormal nasopharynx morphology	Not recorded
Frontal bossing	Not recorded
Thin red part of the upper lip	Not recorded

Abnormality of the nervous system

Trait	How often it is seen
Abnormal corpus callosum morphology	Often (30–79%)
Cerebellar vermis hypoplasia	Often (30–79%)
Global developmental delay	Often (30–79%)
Intellectual disability	Often (30–79%)
Neurodevelopmental delay	Often (30–79%)
Short attention span	Often (30–79%)
Specific learning disability	Often (30–79%)
Ventriculomegaly	Often (30–79%)
Abnormal shape of brain	Sometimes (5–29%)
Agenesis of corpus callosum	Sometimes (5–29%)
Aplasia/Hypoplasia of the cerebellar vermis	Sometimes (5–29%)
Autism spectrum disorder	Sometimes (5–29%)
Delayed ability to walk	Sometimes (5–29%)
Intellectual disability, mild	Sometimes (5–29%)
Poor speech	Sometimes (5–29%)
Underdevelopment of part of brain called corpus callosum	Sometimes (5–29%)

Abnormality of the genitourinary system

Trait	How often it is seen
Hypospadias	Very often (80–99%)
Abnormality of the genitourinary system	Sometimes (5–29%)
Cleft of scrotum	Sometimes (5–29%)
Congenital posterior urethral valve	Sometimes (5–29%)
Enlarged ovaries	Sometimes (5–29%)
Hydronephrosis	Sometimes (5–29%)
Scrotum surrounds penis	Sometimes (5–29%)
Short penis	Sometimes (5–29%)
Undescended testes	Sometimes (5–29%)
Urinary tract abnormalities	Sometimes (5–29%)
Vesicoureteral reflux	Sometimes (5–29%)
Heart shaped uterus	Rarely (1–4%)

Abnormality of the digestive system

Trait	How often it is seen
Poor swallowing	Very often (80–99%)
Abnormal anus position	Sometimes (5–29%)
Abnormal connection between trachea and esophagus	Sometimes (5–29%)
Absent anus	Sometimes (5–29%)
Feeding difficulties in infancy	Sometimes (5–29%)
Inguinal hernia	Sometimes (5–29%)
Omphalocele	Sometimes (5–29%)
Rectourethral fistula	Sometimes (5–29%)
Umbilical hernia	Sometimes (5–29%)
Acid reflux	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Abnormality of the heart	Sometimes (5–29%)
An opening in the wall separating the top two chambers of the heart	Sometimes (5–29%)
Bulge in wall of root of large artery that carries blood away from heart	Sometimes (5–29%)
Hole in heart wall separating two lower heart chambers	Sometimes (5–29%)
Narrowing of aorta	Sometimes (5–29%)
Patent ductus arteriosus	Sometimes (5–29%)
Patent foramen ovale	Sometimes (5–29%)
Persistent left superior vena cava	Sometimes (5–29%)

Abnormality of the respiratory system

Trait	How often it is seen
Laryngeal cleft	Often (30–79%)
Noisy breathing	Sometimes (5–29%)
Floppy windpipe	Rarely (1–4%)
Aspiration	Not recorded
Posterior pharyngeal cleft	Not recorded

Abnormality of the eye

Trait	How often it is seen
Wide-set eyes	Very often (80–99%)
Drooping upper eyelid	Often (30–79%)
Abnormality of refraction	Rarely (1–4%)
Cross-eyed	Rarely (1–4%)

Abnormality of the ear

Trait	How often it is seen
Ears rotated toward back of head	Sometimes (5–29%)
Hearing impairment	Sometimes (5–29%)
Low-set ears	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Congenital diaphragmatic hernia	Sometimes (5–29%)
Vertebral segmentation defect	Rarely (1–4%)

Growth abnormality

Trait	How often it is seen
Short stature	Often (30–79%)
Growth delay	Sometimes (5–29%)

Abnormality of the endocrine system

Trait	How often it is seen
Thyroglossal cyst	Rarely (1–4%)

Abnormality of the immune system

Trait	How often it is seen
Recurrent aspiration pneumonia	Sometimes (5–29%)

Abnormality of the voice

Trait	How often it is seen
Hoarse voice	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 MID1 and how often each is seen. Find out more at hpo.jax.org.

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