{{Rsnum
|rsid=55770810
|Gene=BRCA1
|Orientation=minus
|ReferenceAllele=C
|MissenseAllele=T
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
|Chromosome=17
|position=43063931
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
|Gene_s=BRCA1
}}[[rs55770810]], also known as R1699W, is a SNP in the [[BRCA1]] gene. The more common (C) allele encodes the amino acid arginine (R), while the rare (T) allele encodes a tryptophan (W). 

An analysis of sequence variants of unknown clinical significance in the [[BRCA1]] and [[BRCA2]] genes concluded that this SNP was among the top 10 (over both genes) likely to lead to [[breast cancer]], with a calculated odds of over 1,000:1 against this just being a spurious association. Although the clinical importance has not been proven, this may still be of use for genetic counseling.{{PMID|17924331|OA=1
}}

{{ClinVar
|rsid=55770810
|Reversed=1
|FwdREF=C
|FwdALT=A,T
|REF=G
|ALT=A,T
|RSPOS=41215948
|CHROM=17
|dbSNPBuildID=129
|SSR=0
|SAO=0
|VP=0x050360000000000002110100
|GENEINFO=BRCA1:672
|GENE_NAME=BRCA1
|GENE_ID=672
|WGT=0
|VC=SNV
|CLNALLE=1; 2
|CLNHGVS=NC_000017.10:g.41215948G>A; NC_000017.10:g.41215948G>T
|CLNSIG=5
|Tags=RV;PM;S3D;SLO;OTHERKG;LSD;OM
|CLNACC=RCV000048789.2; RCV000077595.2; RCV000048788.2
|CLNDBN=Familial cancer of breast; Breast-ovarian cancer, familial 1
|CLNDSDB=GeneReviews:MedGen:OMIM:SNOMED_CT; GeneReviews:MedGen:OMIM:Orphanet
|CLNDSDBID=NBK1247:C0346153:114480:254843006; NBK1247:C2676676:604370:145
|Disease=Familial cancer of breast; Breast-ovarian cancer
}}

{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}