rs80357235

Positions:

• chr17-43094410-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_007294.4(BRCA1):​c.1121C>T​(p.Thr374Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,832 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. TL374I?) has been classified as Pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: BRCA1 NM_007294.4 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:4 B:1
• Conservation: PhyloP100: 2.31

Genes affected

BRCA1 (HGNC:1100): (BRCA1 DNA repair associated) This gene encodes a 190 kD nuclear phosphoprotein that plays a role in maintaining genomic stability, and it also acts as a tumor suppressor. The BRCA1 gene contains 22 exons spanning about 110 kb of DNA. The encoded protein combines with other tumor suppressors, DNA damage sensors, and signal transducers to form a large multi-subunit protein complex known as the BRCA1-associated genome surveillance complex (BASC). This gene product associates with RNA polymerase II, and through the C-terminal domain, also interacts with histone deacetylase complexes. This protein thus plays a role in transcription, DNA repair of double-stranded breaks, and recombination. Mutations in this gene are responsible for approximately 40% of inherited breast cancers and more than 80% of inherited breast and ovarian cancers. Alternative splicing plays a role in modulating the subcellular localization and physiological function of this gene. Many alternatively spliced transcript variants, some of which are disease-associated mutations, have been described for this gene, but the full-length natures of only some of these variants has been described. A related pseudogene, which is also located on chromosome 17, has been identified. [provided by RefSeq, May 2020]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
BRCA1	NM_007294.4	c.1121C>T	p.Thr374Ile	missense_variant	10/23	ENST00000357654.9	NP_009225.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
BRCA1	ENST00000357654.9	c.1121C>T	p.Thr374Ile	missense_variant	10/23	1	NM_007294.4	ENSP00000350283	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461832 Hom.: 0 Cov.: 34 AF XY: 0.00000138 AC XY: 1 AN XY: 727218

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:4 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Hereditary cancer-predisposing syndrome Uncertain:1 Benign:1

Likely benign, criteria provided, single submitter	curation	University of Washington Department of Laboratory Medicine, University of Washington	Mar 23, 2023	Missense variant in a coldspot region where missense variants are very unlikely to be pathogenic (PMID:31911673). -
Uncertain significance, criteria provided, single submitter	clinical testing	Ambry Genetics	May 29, 2024	The p.T374I variant (also known as c.1121C>T), located in coding exon 9 of the BRCA1 gene, results from a C to T substitution at nucleotide position 1121. The threonine at codon 374 is replaced by isoleucine, an amino acid with similar properties. This alteration (designated 1240C>T) has been identified in a Spanish breast cancer family (Díez O et al, Int. J. Cancer 1999 Nov; 83(4):465-9). This amino acid position is well conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Mar 21, 2021

Variant summary: BRCA1 c.1121C>T (p.Thr374Ile) results in a non-conservative amino acid change located in the BRCA1, serine-rich domain (IPR025994) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251220 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. c.1121C>T has been reported in the literature under a legacy nomenclature of 1240C>T in a family with individuals affected with Hereditary Breast And Ovarian Cancer Syndrome (Diez_1999). In this family it was reported to co-occur in cis with another adjacent truncation variant reported as 1241delC. The PTT (protein truncation testing) identified a truncated protein product in the probands sample. She had been diagnosed as having BC at 28 years of age. This report does not provide unequivocal conclusions about association of the variant in isolation with Hereditary Breast And Ovarian Cancer Syndrome. To our knowledge, no conclusive experimental evidence demonstrating an impact on protein function has been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation and classified the variant as uncertain significance. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Breast-ovarian cancer, familial, susceptibility to, 1 Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Breast Cancer Information Core (BIC) (BRCA1)

Jan 15, 1999

- -

Hereditary breast ovarian cancer syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jul 10, 2022

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt BRCA1 protein function. ClinVar contains an entry for this variant (Variation ID: 54136). This missense change has been observed in individual(s) with breast and/or ovarian cancer (PMID: 10508480). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with isoleucine, which is neutral and non-polar, at codon 374 of the BRCA1 protein (p.Thr374Ile). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.29
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.57	D;.;.;.;T;T;.;.;T
Eigen	Uncertain	0.55
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Uncertain	0.83	D
LIST_S2	Uncertain	0.88	D;D;D;D;D;D;D;D;D
M_CAP	Uncertain	0.24	D
MetaRNN	Uncertain	0.72	D;D;D;D;D;D;D;D;D
MetaSVM	Uncertain	0.36	D
MutationAssessor	Pathogenic	3.0	M;M;.;.;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D;N;N;N;N;N;N
PrimateAI	Benign	0.40	T
PROVEAN	Pathogenic	-5.5	D;D;D;D;.;D;D;D;D
REVEL	Pathogenic	0.68
Sift	Uncertain	0.0080	D;D;D;D;.;D;D;D;D
Sift4G	Uncertain	0.013	D;D;D;D;.;D;.;D;D
Polyphen		1.0	D;.;.;P;.;.;.;.;.
Vest4		0.61
MutPred		0.43		Gain of helix (P = 0.0078);Gain of helix (P = 0.0078);.;Gain of helix (P = 0.0078);.;Gain of helix (P = 0.0078);.;.;Gain of helix (P = 0.0078);
MVP		0.96
MPC		0.35
ClinPred		0.98	D
GERP RS		2.7
Varity_R		0.21
gMVP		0.10

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs80357235; hg19: chr17-41246427;