Traits

Traits linked to MAN2B1

mannosidase alpha class 2B member 1

The Human Phenotype Ontology links 130 traits to MAN2B1, by body system: features seen in people with one of the gene's rare conditions.

MAN2B1

Abnormality of the nervous system

Trait	How often it is seen
Delayed speech and language development	Very often (80–99%)
Intellectual disability	Very often (80–99%)
Intellectual disability, mild	Very often (80–99%)
Specific learning disability	Very often (80–99%)
Ataxia	Often (30–79%)
Decrease in size of the outer layer of the brain due to loss of brain cells	Often (30–79%)
Degeneration of cerebellum	Often (30–79%)
Motor delay	Often (30–79%)
Short attention span	Often (30–79%)
Anxiety	Sometimes (5–29%)
Behavioral abnormality	Sometimes (5–29%)
Chiari malformation	Sometimes (5–29%)
Clumsiness	Sometimes (5–29%)
Confusion	Sometimes (5–29%)
Corpus callosum atrophy	Sometimes (5–29%)
Delusions	Sometimes (5–29%)
Depression	Sometimes (5–29%)
Drowsiness	Sometimes (5–29%)
Hallucinations	Sometimes (5–29%)
Subcortical cerebral atrophy	Sometimes (5–29%)
Communicating hydrocephalus	Rarely (1–4%)
Loss of speech	Rarely (1–4%)
Abnormal pyramidal sign	Not recorded
Babinski sign	Not recorded
Delayed myelination	Not recorded
Difficulty articulating speech	Not recorded
Gliosis	Not recorded
Global developmental delay	Not recorded
Inability to coordinate movements when walking	Not recorded
Increased reflexes	Not recorded
Limb ataxia	Not recorded
Spinocerebellar tract disease in lower limbs	Not recorded

Abnormality of head or neck

Trait	How often it is seen
Enlarged cisterna magna	Very often (80–99%)
Coarse facial features	Often (30–79%)
Facial shape deformation	Often (30–79%)
Abnormal sella turcica morphology	Sometimes (5–29%)
Abnormality of the sphenoid sinus	Sometimes (5–29%)
Abnormally large tongue	Sometimes (5–29%)
Big calvaria	Sometimes (5–29%)
Big lower jaw	Sometimes (5–29%)
Broad forehead	Sometimes (5–29%)
Broad head shape	Sometimes (5–29%)
Decreased facial muscle tone	Sometimes (5–29%)
Deformity of the skull	Sometimes (5–29%)
Depressed nasal bridge	Sometimes (5–29%)
Enlargement of skull bones	Sometimes (5–29%)
Flat face	Sometimes (5–29%)
Highly arched eyebrow	Sometimes (5–29%)
Increased thickness of skull cap	Sometimes (5–29%)
Prominent forehead	Sometimes (5–29%)
Short neck	Sometimes (5–29%)
Widely spaced teeth	Sometimes (5–29%)
Eye folds	Not recorded
Flat back of skull	Not recorded
Flat nose	Not recorded
Frontal bossing	Not recorded
Gum enlargement	Not recorded
Low frontal hairline	Not recorded
Midface retrusion	Not recorded
Thick eyebrow	Not recorded
Zygomatic flattening	Not recorded

Abnormality of the musculoskeletal system

Trait	How often it is seen
Abnormally shaped skeletal	Very often (80–99%)
Dysostosis multiplex	Very often (80–99%)
Low muscle tone	Often (30–79%)
Muscle tissue disease	Often (30–79%)
Breakdown of bone	Sometimes (5–29%)
Death of bone due to decreased blood supply	Sometimes (5–29%)
Double-Jointed	Sometimes (5–29%)
Flattened vertebrae	Sometimes (5–29%)
Funnel chest	Sometimes (5–29%)
Hypoplastic inferior ilia	Sometimes (5–29%)
Joint stiffness	Sometimes (5–29%)
Low muscle tone in trunk	Sometimes (5–29%)
Osteopenia	Sometimes (5–29%)
Pigeon chest	Sometimes (5–29%)
Spastic paraplegia	Sometimes (5–29%)
Thickened ribs	Sometimes (5–29%)
Abnormality of the rib cage	Not recorded
Displacement of one backbone compared to another	Not recorded
Generalized decreased muscle tone	Not recorded
Increased vertebral height	Not recorded
Involuntary muscle stiffness, contraction, or spasm	Not recorded
Thoracolumbar kyphosis	Not recorded

Abnormality of the eye

Trait	How often it is seen
Close sighted	Often (30–79%)
Clouding of the lens of the eye	Often (30–79%)
Cross-eyed	Often (30–79%)
Farsightedness	Often (30–79%)
Wide-set eyes	Often (30–79%)
Astigmatism	Sometimes (5–29%)
Bulging eye	Sometimes (5–29%)
Corneal opacity	Sometimes (5–29%)
Optic disc pallor	Sometimes (5–29%)
Impaired smooth pursuit	Not recorded
Involuntary, rapid, rhythmic eye movements	Not recorded
Retina degeneration	Not recorded

Abnormality of limbs

Trait	How often it is seen
Bilateral coxa valga	Sometimes (5–29%)
Club foot on both sides	Sometimes (5–29%)
Cortical thickening of long bone diaphyses	Sometimes (5–29%)
Knock knees	Sometimes (5–29%)
Talipes valgus	Sometimes (5–29%)
Bowed thighbone	Not recorded

Abnormality of the cardiovascular system

Trait	How often it is seen
Enlarged liver and spleen	Often (30–79%)
Mitral regurgitation	Sometimes (5–29%)
Aortic regurgitation	Rarely (1–4%)
Increased spleen size	Not recorded

Abnormality of the digestive system

Trait	How often it is seen
Recurrent gastroenteritis	Often (30–79%)
Umbilical hernia	Sometimes (5–29%)
Enlarged liver	Not recorded
Inguinal hernia	Not recorded

Abnormality of the ear

Trait	How often it is seen
Middle ear infection	Very often (80–99%)
Mixed hearing impairment	Often (30–79%)
Sensorineural hearing impairment	Sometimes (5–29%)
Large ears	Not recorded

Abnormality of the immune system

Trait	How often it is seen
Decreased immune function	Very often (80–99%)
Recurrent infections	Very often (80–99%)
Pneumonia	Often (30–79%)
Recurrent bacterial infections	Not recorded

Laboratory abnormality

Trait	How often it is seen
Decreased circulating alpha-mannosidase activity	Always
Abnormal circulating enzyme concentration or activity	Very often (80–99%)
Oligosacchariduria	Very often (80–99%)
Reduced leukocyte alpha-mannosidase activity	Not recorded

Abnormality of blood and blood-forming tissues

Trait	How often it is seen
Low blood cell count	Sometimes (5–29%)
Vacuolated lymphocytes	Not recorded

Abnormality of the integument

Trait	How often it is seen
Soft skin	Sometimes (5–29%)
Excessive hair growth	Not recorded

Growth abnormality

Trait	How often it is seen
Disproportionate tall stature	Sometimes (5–29%)
Growth delay	Not recorded

Abnormal cellular phenotype

Trait	How often it is seen
Decreased circulating antibody level	Not recorded

Abnormality of the genitourinary system

Trait	How often it is seen
Frequent urinary tract infections	Rarely (1–4%)

Constitutional symptom

Trait	How often it is seen
Lack of energy and strength	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 MAN2B1 and how often each is seen. Find out more at hpo.jax.org.

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