Traits

Traits linked to BTD

biotinidase

The Human Phenotype Ontology links 49 traits to BTD, by body system: features seen in people with one of the gene's rare conditions.

Abnormality of the nervous system

Trait	How often it is seen
Abnormality of the nervous system	Often (30–79%)
Ataxia	Often (30–79%)
Brain imaging abnormality	Often (30–79%)
Epilepsy	Often (30–79%)
Global developmental delay	Often (30–79%)
Focal motor seizure	Sometimes (5–29%)
Generalized myoclonic seizure	Sometimes (5–29%)
Grand mal seizures	Sometimes (5–29%)
Infantile spasms	Sometimes (5–29%)
Intellectual disability	Sometimes (5–29%)
Lethargy	Sometimes (5–29%)
Myelopathy	Sometimes (5–29%)
Diffuse cerebellar atrophy	Not recorded
Diffuse cerebral atrophy	Not recorded

Abnormality of the immune system

Trait	How often it is seen
Abnormality of the immune system	Often (30–79%)
Skin rash	Often (30–79%)
Eczema	Sometimes (5–29%)
Recurrent Candida infection	Sometimes (5–29%)
Recurrent fungal infections	Sometimes (5–29%)
Recurrent viral infections	Sometimes (5–29%)
Recurrent skin infections	Not recorded
Seborrheic dermatitis	Not recorded

Abnormality of the eye

Trait	How often it is seen
Optic atrophy	Often (30–79%)
Abnormality of the eye	Sometimes (5–29%)
Blind spot	Sometimes (5–29%)
Damaged optic nerve	Sometimes (5–29%)
Nonprogressive visual loss	Sometimes (5–29%)
Visual loss	Not recorded

Abnormality of the respiratory system

Trait	How often it is seen
Apnea	Sometimes (5–29%)
Breathing difficulties	Sometimes (5–29%)
Increased respiratory rate or depth of breathing	Sometimes (5–29%)
Laryngeal stridor	Sometimes (5–29%)
Rapid breathing	Sometimes (5–29%)

Abnormality of the digestive system

Trait	How often it is seen
Diarrhea	Not recorded
Enlarged liver	Not recorded
Feeding difficulties in infancy	Not recorded
Vomiting	Not recorded

Laboratory abnormality

Trait	How often it is seen
Decreased circulating biotinidase concentration	Very often (80–99%)
Metabolic ketoacidosis	Very often (80–99%)
Organic aciduria	Very often (80–99%)
High blood ammonia levels	Often (30–79%)

Abnormality of the ear

Trait	How often it is seen
Sensorineural hearing impairment	Often (30–79%)
Hearing impairment	Sometimes (5–29%)

Abnormality of the musculoskeletal system

Trait	How often it is seen
Low muscle tone	Very often (80–99%)
Spastic paraparesis	Sometimes (5–29%)

Abnormality of head or neck

Trait	How often it is seen
Pink eye	Often (30–79%)

Abnormality of limbs

Trait	How often it is seen
Limb muscle weakness	Sometimes (5–29%)

Abnormality of the cardiovascular system

Trait	How often it is seen
Increased spleen size	Not recorded

Abnormality of the integument

Trait	How often it is seen
Hair loss	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 BTD and how often each is seen. Find out more at hpo.jax.org.

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