Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2
The NM_007294.4(BRCA1):c.3354G>T(p.Gln1118His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,038 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. Q1118E) has been classified as Uncertain significance.
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]
Verdict is Uncertain_significance. Variant got 2 ACMG points.
PM2
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PM2 - Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium
Very rare variant in population databases, with high coverage;
Uncertain significance, criteria provided, single submitter
clinical testing
Ambry Genetics
Jan 24, 2020
The p.Q1118H variant (also known as c.3354G>T), located in coding exon 9 of the BRCA1 gene, results from a G to T substitution at nucleotide position 3354. The glutamine at codon 1118 is replaced by histidine, an amino acid with highly similar properties. This amino acid position is not well conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -
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). -
not provided Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Women's Health and Genetics/Laboratory Corporation of America, LabCorp
Oct 13, 2016
Variant summary: The BRCA1 c.3354G>T (p.Gln1118His) variant involves the alteration of a non-conserved nucleotide. This variant is not located in any known domain (InterPro). 2/4 in silico tools predict a benign outcome for this variant. This variant is absent from 121140 control chromosomes from ExAC. The variant has been reported to co-occur with a known deleterious variant BRCA1 p.W1508X (BIC). Co-occurrence with the same pathogenic variant was noted in an internal sample undergoing genetic testing. This data strongly supports a benign outcome of Q1118H. Multiple clinical diagnostic laboratories have classified this variant as uncertain significance without evidence to independently evaluate. Taken together, this variant is classified as VUS-possibly benign variant based on two independent records of co-occurrence with the same pathgenic variant. -
Hereditary breast ovarian cancer syndrome Uncertain:1
Uncertain significance, criteria provided, single submitter
clinical testing
Invitae
Jul 12, 2023
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: 37525). This missense change has been observed in individual(s) with Breast Cancer Information Core database (PMID: 10923033). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glutamine, which is neutral and polar, with histidine, which is basic and polar, at codon 1118 of the BRCA1 protein (p.Gln1118His). -