12-132687314-A-G
Variant summary
Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PVS1_ModeratePS1_ModeratePP5
The NM_006231.4(POLE):āc.2T>Cā(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000107 in 1,501,040 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).
Frequency
Consequence
NM_006231.4 start_lost
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Uncertain_significance. Variant got 5 ACMG points.
Transcripts
RefSeq
Ensembl
Frequencies
GnomAD3 genomes AF: 0.00000659 AC: 1AN: 151838Hom.: 0 Cov.: 33
GnomAD3 exomes AF: 0.0000276 AC: 3AN: 108772Hom.: 0 AF XY: 0.0000166 AC XY: 1AN XY: 60308
GnomAD4 exome AF: 0.0000111 AC: 15AN: 1349202Hom.: 0 Cov.: 32 AF XY: 0.00000751 AC XY: 5AN XY: 665772
GnomAD4 genome AF: 0.00000659 AC: 1AN: 151838Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0AN XY: 74160
ClinVar
Submissions by phenotype
not provided Pathogenic:2Uncertain:1
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The c.2T>C variant in the POLE gene results in the loss of the initiator Methionine codon, and the resultant protein would be described as p.Met1?" to signify that it is not known if the loss of Met1 prevents all protein translation or if an abnormal protein is produced using an alternate Methionine codon. This variant has not, to our knowledge, been published in the literature as pathogenic or benign. POLE c.2T>C was not observed in approximately 3,900 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, suggesting it is not a common benign variant in these populations. While some missense variants have been recognized as an underlying cause of Polymerase Proofreading-Associated Polyposis (PPAP), there are no data at this time to support that loss-of-function variants confer the same cancer risks. We therefore consider POLE c.2T>C to be a variant of unknown significance with respect to cancer.To date, the majority of publications regarding POLE and colorectal cancer risk are confined to missense variants within the exonuclease domain (Palles 2013, Spier 2015). However, a splice variant and a frameshift variant have been reported. Pachlopnik Schmid et al. (2012) observed a splice variant at the +3 position in intron 34, in the homozygous state, in 11 family members with facial dysmorphism, immunodeficiency, livedo, and short stature (FILS) from a large consanguineous family; however, they noted that all heterozygous carriers were asymptomatic and did not have a history of cancer. While Smith et al. (2013) identified a POLE frameshift variant in a 26 year old with a history of colorectal cancer, no family history was provided and segregation analysis was not completed. As described above, facial dysmorphism, immunodeficiency, livedo, and short stature (FILS) appears to be a rare autosomal recessive condition associated with two loss-of-function variants in POLE (Pachlopnik Schmid 2012). For individuals and family members of reproductive age, assessment of the reproductive risk associated with being a carrier of a potential loss of function POLE variant may be considered." -
This sequence change affects the initiator methionine of the POLE mRNA. The next in-frame methionine is located at codon 44. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. Disruption of the initiator codon has been observed in individual(s) with clinical features of autosomal recessive FILS syndrome (PMID: 30503519). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 246154). For these reasons, this variant has been classified as Pathogenic. -
Hereditary cancer-predisposing syndrome Uncertain:1
The p.M1? variant (also known as c.2T>C), located in coding exon 1 of the POLE gene, results from a T to C substitution at nucleotide position 2. This alters the methionine residue at the initiation codon (ATG). Another variant at this codon (c.1A>T) has been identified in conjunction with a second POLE variant (c.1686+32C>G) in individuals with features consistent with POLE deficiency; in at least one instance, the variants were identified in trans (Logan CV et al. Am J Hum Genet, 2018 Dec;103:1038-1044). This amino acid position is well conserved in available vertebrate species. In addition to the clinical data presented in the literature, sequence variations that modify the initiation codon are expected to result in either loss of translation initiation, N-terminal truncation, or cause a shift in the mRNA reading frame. Based on the supporting evidence, this alteration is pathogenic for POLE deficiency; however, the association of this alteration with POLE-related polymerase proofreading-associated polyposis (PPAP) and POLE-related CMMRD-like syndrome is unknown. -
Colorectal cancer, susceptibility to, 12;C3554576:Facial dysmorphism-immunodeficiency-livedo-short stature syndrome;C5193036:Intrauterine growth retardation, metaphyseal dysplasia, adrenal hypoplasia congenita, genital anomalies, and immunodeficiency Uncertain:1
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Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at