Is BTD p.Gln86Ter (c.256C>T) pathogenic?

BTD p.Gln86Ter (c.256C>T) is classified Pathogenic/Likely pathogenic in BTD (ClinVar, Multiple submitters, 3 submitters; last evaluated 2023-10-17). Absent from gnomAD v4.1; Associated with biotinidase deficiency.

What condition is associated with BTD p.Gln86Ter (c.256C>T)?

BTD p.Gln86Ter (c.256C>T) is associated with biotinidase deficiency (ClinVar).

How common is BTD p.Gln86Ter (c.256C>T) in the general population?

BTD p.Gln86Ter (c.256C>T) is absent from gnomAD v4.1 (gnomAD).

How is Biotinidase deficiency inherited?

Typically Autosomal recessive (Orphanet). A genetic counselor can assess individual risk for a family.

BTD p.Gln86Ter

c.256C>T · rs1553653062 · VCV554090

Pathogenic/Likely pathogenic Multiple submitters

Classification

Pathogenic/Likely pathogenic

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 3 submitters

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Not reported

no allele count reported in gnomAD v4.1 (AN 1,609,096)

Conditions

biotinidase deficiency

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Consequence	nonsense (stop-gain)	predicted loss-of-function
NMD	predicted	premature termination codon in exon 3 of 4
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.7	GERP 2.2, phastCons 1
Overall
CADD	40.0	PHRED · no single calibrated threshold — expert panels disagree

Predicted loss-of-function is descriptive, not an applied PVS1 code.

Population frequency

gnomAD v4.1 · exomes + genomes

No allele count reported in gnomAD v4.1 (AN 1,609,096). This is missing data, not an absence: the variant may or may not be present in gnomAD. Rarity (ACMG PM2) and BA1/BS1 cannot be assessed for it.

Variant & gene context

Gene: BTD
Protein: p.Gln86Ter
Coding: c.256C>T
MANE Select: NM_001370658
dbSNP: rs1553653062
Type: single nucleotide variant
Location: chr3:15641914 (GRCh38)
Gene constraint: LOEUF 1.22 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 86.77
Residue 86: the cn hydrolase domain

Full BTD gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

biotinidase deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Biotinidase deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Adolescent, Adult, Childhood, Infancy, Neonatal
Prevalence: 1-9 / 100 000 (Worldwide)

Similar variants

BTD p.Gln86fs Likely pathogenic ★ same residue
BTD p.Gln86Arg Uncertain significance ★ ⚠ same residue
BTD c.1330G>C Pathogenic ★★ same condition
BTD c.249+1G>T Likely pathogenic ★★ same condition
BTD c.400-2A>G Likely pathogenic ★★ same condition
BTD c.-17+2T>C Pathogenic/Likely pathogenic ★★ same condition
BTD p.Ala142Val Pathogenic/Likely pathogenic ★★ same condition
BTD p.Ala217Thr Pathogenic/Likely pathogenic ★★ ⚠ same condition

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/btd-p-gln86ter (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown