Gene

BTD

biotinidase

Cytogenetic location: 3p25.1
Coordinates: Chromosome 3: 15,601,745–15,653,714 (GRCh38)
Exons: 4 exons across 52 kb
Protein: 523 amino acids
Inheritance: Autosomal recessive
MANE Select transcript: ENST00000643237.3NM_001370658.1
Locus type: gene with protein product

Very high
Confident
Low
Very low

Reference genomeGRCh38hg38

Positions on gene and variant pages follow this choice, in this browser.

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Curated reports relevant to this gene

Biotinidase & Holocarboxylase Deficiency
- Biotinidase and Holocarboxylase Synthetase Deficiency (Multiple Carboxylase Deficiency)Autosomal recessive
  Caused by variants in BTD or HLCS, these conditions can lead to seizures, skin rash, hair loss, hearing and vision loss and metabolic crises if untreated; some BTD variants cause only partial enzyme deficiency, which is usually mild.
  - ClinGen rates the link definitive
  - 7 GenCC submitters rate it definitive or strong
  - On the ACMG secondary findings list
  What knowing changes
  Knowing allows inexpensive lifelong biotin treatment, which can prevent the serious neurological and metabolic effects of profound deficiency.

Broader groupings

Leigh Syndrome
- One of 69 genes linked to it
  A progressive neurological disease defined by specific neuropathological features associating brainstem and basal ganglia lesions.
  - ClinGen rates the link moderate

Inheritance

Autosomal recessive: It takes a changed copy from each parent. With one, you are a carrier and usually unaffected; when both parents are carriers, each child has a one-in-four chance of inheriting two.

How BTD is laid out

Coding sequence
Untranslated region
Intron
Direction of transcription
Known disease-causing sites
Stretches short reads find hard
Variants with a page

Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.

Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).

Nearby genes from Ensembl release 116, on GRCh38.

Exons make up 10 kb of the gene's 52 kb; 1,572 of those bases code for the protein.

How a genome test reads BTD

213

positions in BTD where ClinVar classes a change as pathogenic or likely pathogenic

None of them falls in a region short reads find hard.

A whole genome covers all 52 kb of BTD, introns included, not only the 10 kb of exons.

Variants with a page (112)

The BTD variants with a page here, most review stars first. Each page describes ClinVar's public record of the variant, never a result.

Variant	HGVS c.	Exon or intron	Position (GRCh38)	ClinVar classification	Review status
A142V	c.425C>T	Exon 4	15,644,341	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
A217T	c.649G>A	Exon 4	15,644,565	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
A269V	c.806C>T	Exon 4	15,644,722	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
A279P	c.835G>C	Exon 4	15,644,751	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
A419D	c.1256C>A	Exon 4	15,645,172	Pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
A458P	c.1372G>C	Exon 4	15,645,288	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
c.-17+1G>A		Intron 1	15,601,895	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
c.-17+2T>C		Intron 1	15,601,896	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
c.250-15del		Intron 2	15,641,892	Pathogenic/likely pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts
c.359G>A		Exon 3	15,642,017	Pathogenic	2 stars out of 4 criteria provided, multiple submitters, no conflicts

See all 112 BTD variants →

Traits linked to BTD

The Human Phenotype Ontology lists these as features of the rare conditions BTD can cause. Each trait's page lists the other genes linked to it.

Abnormality of the nervous system

Show 6 more traits

Abnormality of the immune system

Abnormality of the eye

Abnormality of the respiratory system

Abnormality of the digestive system

Laboratory abnormality

Abnormality of the ear

Abnormality of the musculoskeletal system

External links

Gene records

Transcript

Protein

Variants

Clinical

Where this comes from

HGNC: the gene's symbol, name, other symbols and location.
MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
The ACMG secondary findings list, SF v3.2.
ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
Data release 2026.10.16-c6eea6bf.

Cite this page

APA

Dante Labs. (n.d.). BTD gene: biotinidase. Retrieved 16 October 2026, from https://dantelabs.com/genes/btd

Vancouver

Dante Labs. BTD gene: biotinidase [Internet]. [cited 16 October 2026]. Available from: https://dantelabs.com/genes/btd

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