--- title: "BTD C166G (c.496T>G, rs955385869) | Dante Labs" description: "ClinVar classifies BTD C166G as Likely pathogenic (criteria provided, multiple submitters, no conflicts). Where it sits in the genome, its predicted effect, and the Genome Test reports that look at it." url: "https://dantelabs.com/genes/btd/variants/c166g" --- 1. [Genes](https://dantelabs.com/genes) 2. [BTD](https://dantelabs.com/genes/btd) 3. BTD C166G Variant # BTD C166G NM_001370658.1(BTD):c.496T>G (p.Cys166Gly) Also known as - p.Cys166Gly - p.C166G - rs955385869 * ClinVar classification Likely pathogenic * Review status 2 stars out of 4 criteria provided, multiple submitters, no conflicts * Last evaluated 8 May 2023 Data current to ClinVar release 2026-10-12 · Dante Labs data release 2026.10.16-c6eea6bf Facts last changed 16 October 2026 ## Summary C166G is a missense variant in BTD: it changes a single amino acid in the protein the gene encodes. ClinVar classifies it as likely pathogenic for biotinidase deficiency (criteria provided, multiple submitters, no conflicts). ## ClinVar classifications | Condition | Classification | Review status | Submissions | Last evaluated | | ------------------------------------------------------------------------------------------------------------------------- | ----------------- | --------------------------------------------------------------------- | ------------- | -------------- | | biotinidase deficiency[ClinVar VCV000801945 (opens in a new tab)](https://www.ncbi.nlm.nih.gov/clinvar/variation/801945/) | Likely pathogenic | 2 stars out of 4 criteria provided, multiple submitters, no conflicts | 2 submissions | 8 May 2023 | Classifications as ClinVar records them in release 2026-10-12. ClinVar updates them as evidence is reviewed. ## Where it lies in BTD C166G lies in exon 4 of the 4 in BTD's MANE Select transcript, NM_001370658.1. [BTD variants in exon 4 →](https://dantelabs.com/genes/btd/variants?exon=4) [BTD's gene diagram →](https://dantelabs.com/genes/btd#gene-structure) ## Molecular details | Gene | [BTD](https://dantelabs.com/genes/btd) | | --------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------- | | Transcript | NM_001370658.1 MANE Select | | Coding DNA change (HGVS c.) | c.496T>G | | Protein change (HGVS p.) | p.Cys166Gly p.C166G | | Predicted consequence | Missense [missense_variant (opens in a new tab)](https://purl.obolibrary.org/obo/SO_0001583) | | Predicted impact | Moderate | | Position (GRCh38) | chr3:15644412 T>G | | Position (GRCh37) | chr3:15685919 T>G | | dbSNP ID | [rs955385869 (opens in a new tab)](https://www.ncbi.nlm.nih.gov/snp/rs955385869) | | ClinVar Variation ID | [VCV000801945 (opens in a new tab)](https://www.ncbi.nlm.nih.gov/clinvar/variation/801945/) | | ClinVar Allele ID | 790350 | | ClinGen Allele Registry ID | [CA70621546 (opens in a new tab)](https://reg.clinicalgenome.org/redmine/projects/registry/genboree_registry/by_canonicalid?canonicalid=CA70621546) | | ClinVar name | NM_001370658.1(BTD):c.496T>G (p.Cys166Gly) | ## BTD C166G in other databases - [ClinVar VCV000801945 (opens in a new tab)](https://www.ncbi.nlm.nih.gov/clinvar/variation/801945/) - [dbSNP rs955385869 (opens in a new tab)](https://www.ncbi.nlm.nih.gov/snp/rs955385869) - [ClinGen Allele Registry CA70621546 (opens in a new tab)](https://reg.clinicalgenome.org/redmine/projects/registry/genboree_registry/by_canonicalid?canonicalid=CA70621546) - [gnomAD 3-15644412-T-G (opens in a new tab)](https://gnomad.broadinstitute.org/variant/3-15644412-T-G?dataset=gnomad_r4) - [Ensembl rs955385869 (opens in a new tab)](https://www.ensembl.org/Homo_sapiens/Variation/Explore?v=rs955385869) ## Reports that look at this variant (1) These Genome Test condition reports include C166G among the variants they look at. | Report | Conditions | Inheritance | | ----------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------- | ------------------- | | [Biotinidase & Holocarboxylase Deficiency](https://dantelabs.com/conditions/biotinidase-and-holocarboxylase-deficiency) | Biotinidase and Holocarboxylase Synthetase Deficiency (Multiple Carboxylase Deficiency) | Autosomal recessive | ## Other variants in BTD - [A142V Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/a142v) - [A217T Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/a217t) - [A269V Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/a269v) - [A279P Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/a279p) - [A419D Pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/a419d) - [A458P Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/a458p) - [c.-17+1G>A Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/c--17plus1g-a) - [c.-17+2T>C Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/c--17plus2t-c) - [c.250-15del Pathogenic/likely pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/c-250-15del) - [c.359G>A Pathogenic 2 stars out of 4](https://dantelabs.com/genes/btd/variants/c-359g-a) [All BTD variants](https://dantelabs.com/genes/btd/variants) ## Limitations This page describes publicly available information about a genetic variant. It is not a diagnosis, and it says nothing about whether you or anyone else carries this variant. Classifications come from ClinVar and change as new evidence is reviewed. A classification here may differ from the one in ClinVar today, or from the one a laboratory reports. Whole genome sequencing with short reads can miss or miscall some variants, particularly in repeated or highly similar stretches of DNA and in large insertions, deletions or rearrangements. If you have questions about a variant in your own results or in your family, talk to a genetic counsellor or your doctor. ## Sources & credits - Classifications from ClinVar (release 2026-10-12), National Center for Biotechnology Information. - Condition terms from the Mondo Disease Ontology (release 2026-10-06), used under CC BY 4.0. - Gene symbols and names from the HUGO Gene Nomenclature Committee (release 2026-10-16). - Allele identifiers from the ClinGen Allele Registry (release 2026-10-16-c4908f54). - Reference SNP identifiers from dbSNP (release b157), National Center for Biotechnology Information. - Gene–disease links from the Gene Curation Coalition, GenCC (release 2026-10-16). - Difficult regions from the Genome in a Bottle Consortium (release v3.6). - Transcripts from MANE (release v1.5), NCBI and EMBL-EBI. - Predicted consequences from mehari (release 0.11.0), with transcript models from cdot. - Built from Dante Labs data release 2026.10.16-c6eea6bf of 16 October 2026. ## Cite this page APA > Dante Labs. (16 October 2026). BTD C166G (c.496T>G, rs955385869) (Version 2026.10.16-c6eea6bf). Retrieved 17 October 2026, from https\://dantelabs.com/genes/btd/variants/c166g Vancouver > Dante Labs. BTD C166G (c.496T>G, rs955385869) \[Internet]. Version 2026.10.16-c6eea6bf. 16 October 2026 \[cited 17 October 2026]. Available from: https\://dantelabs.com/genes/btd/variants/c166g Download citation [RIS](https://dantelabs.com/genes/btd/variants/c166g/cite.ris) [BibTeX](https://dantelabs.com/genes/btd/variants/c166g/cite.bib) [CSL-JSON](https://dantelabs.com/genes/btd/variants/c166g/cite.json) ## Read your whole genome From $449 Free shipping · Results in 6–8 weeks [Explore the Genome Test](https://dantelabs.com/whole-genome-sequencing)