Traits

Traits linked to MAN1B1

mannosidase alpha class 1B member 1

The Human Phenotype Ontology links 67 traits to MAN1B1, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of head or neck

Trait	How often it is seen
Abnormal facial shape	Very often (80–99%)
Downward slanting of the opening between the eyelids	Very often (80–99%)
Big calvaria	Often (30–79%)
Broad eyebrow	Often (30–79%)
Bulbous nose	Often (30–79%)
Limited hair on end of eyebrow	Often (30–79%)
Long eyebrows	Often (30–79%)
Long, narrow head	Often (30–79%)
Pointed chin	Often (30–79%)
Prominent nose	Often (30–79%)
Short philtrum	Often (30–79%)
Sparse eyebrow	Often (30–79%)
Thin red part of the upper lip	Often (30–79%)
Underdeveloped nasolabial fold	Often (30–79%)
Wide nasal bridge	Often (30–79%)
Flat back of skull	Sometimes (5–29%)
Frontal bossing	Sometimes (5–29%)
Highly arched eyebrow	Sometimes (5–29%)
Long face	Sometimes (5–29%)
Short chin	Sometimes (5–29%)
Short neck	Sometimes (5–29%)
Smooth philtrum	Sometimes (5–29%)
Wide nose	Sometimes (5–29%)
Zygomatic flattening	Sometimes (5–29%)
Eye folds	Rarely (1–4%)
Full lips	Rarely (1–4%)
Long eyelashes	Rarely (1–4%)
Outward turned lips	Rarely (1–4%)

Abnormality of the nervous system

Trait	How often it is seen
Global developmental delay	Always
Intellectual disability	Always
IQ between 34 and 49	Always
Motor delay	Always
Abnormal shape of brain	Often (30–79%)
Intellectual disability, mild	Often (30–79%)
Poor speech	Often (30–79%)
Aggressive behavior	Sometimes (5–29%)
Ataxia	Sometimes (5–29%)
Autism	Sometimes (5–29%)
Autism spectrum disorder	Sometimes (5–29%)
Behavioral abnormality	Sometimes (5–29%)
Epilepsy	Sometimes (5–29%)
Increased appetite	Sometimes (5–29%)
Intellectual disability, severe	Sometimes (5–29%)
Small cerebellum	Sometimes (5–29%)
Wide based walk	Sometimes (5–29%)
Periventricular heterotopia	Rarely (1–4%)
Resting tremor	Rarely (1–4%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Decreased muscle tone in infant	Very often (80–99%)
Double-Jointed	Often (30–79%)
Low muscle tone	Often (30–79%)
Flexed joint that cannot be straightened	Sometimes (5–29%)
Pigeon chest	Sometimes (5–29%)

Abnormality of the eye

Trait	How often it is seen
Cross-eyed	Often (30–79%)
Wide-set eyes	Often (30–79%)
Farsightedness	Sometimes (5–29%)

Abnormality of the integument

Trait	How often it is seen
Hanging skin	Often (30–79%)
Abnormal position of hair whorl	Sometimes (5–29%)
Multiple birthmarks	Rarely (1–4%)

Growth abnormality

Trait	How often it is seen
Truncal obesity	Often (30–79%)
Obesity	Sometimes (5–29%)
Short stature	Sometimes (5–29%)

Abnormality of limbs

Trait	How often it is seen
Curvature of little finger	Sometimes (5–29%)
Webbed 2nd and 3rd toes	Rarely (1–4%)

Abnormality of the ear

Trait	How often it is seen
Large ears	Always
Low-set ears	Often (30–79%)

Abnormality of the breast

Trait	How often it is seen
Inverted nipples	Often (30–79%)

Laboratory abnormality

Trait	How often it is seen
Type II transferrin isoform profile	Often (30–79%)

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 MAN1B1 and how often each is seen. Find out more at hpo.jax.org.

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