12-132687314-A-T
Variant summary
Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PVS1_ModeratePS1_ModeratePP5
The NM_006231.4(POLE):c.2T>A(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 0.0000167 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: 0.0000497 AC XY: 3AN XY: 60308
GnomAD4 exome AF: 0.0000178 AC: 24AN: 1349202Hom.: 0 Cov.: 32 AF XY: 0.0000195 AC XY: 13AN XY: 665772
GnomAD4 genome AF: 0.00000659 AC: 1AN: 151838Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1AN XY: 74160
ClinVar
Submissions by phenotype
not provided Pathogenic:1Uncertain:1
The c.2T>A variant in the POLE gene alters 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>A was not observed at a significant allele frequency in large population cohorts (Lek 2016). While missense variants located within the exonuclease domain of the POLE gene have been recognized as an underlying cause of Polymerase Proofreading-Associated Polyposis (PPAP), an autosomal dominant condition associated with polyposis and an increased risk for colon cancer (Palles 2013, Spier 2015), there are no data to support that loss-of-function variants, such as this one, confer the same cancer risks. Smith et al. (2013) identified a POLE frameshift variant in a 26 year old with a history of colorectal cancer, but no information about family history was provided. We therefore consider POLE c.2T>A to be a variant of unknown significance with respect to cancer. A recessive disease associated with POLE has been reported in the literature. In one large consanguineous family, 14 affected relatives with a syndrome called FILS (facial dysmorphism, immunodeficiency, livedo, and short stature) were all found to be homozygous for POLE c.4444+3A>G, a splice variant which results in a small proportion (~10%) of normal POLE transcript (Pachlopnik Schmid 2012). In addition, an unrelated individual with a suspected chromosome instability syndrome was also found to be homozygous for POLE c.4444+3A>G (Thiffault 2015). We cannot assess whether the variant identified in the current patient would cause the same recessive disease. Individuals and family members of reproductive age may choose to consider assessment of potential reproductive risks. -
This sequence change affects the initiator methionine of the POLE mRNA. The next in-frame methionine is located at codon 44. This variant is present in population databases (no rsID available, gnomAD 0.008%). 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: 473569). 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>A), located in coding exon 1 of the POLE gene, results from a T to A 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). 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. Although biallelic loss of function of POLE has been associated with autosomal recessive POLE deficiency, haploinsufficiency of POLE has not been established as a mechanism of disease for POLE-related polymerase proofreading-associated polyposis (PPAP) and POLE-related CMMRD-like syndrome. Based on the supporting evidence, this variant is expected to be causative of POLE deficiency when present along with a second pathogenic variant on the other allele; however, its clinical significance for PPAP and POLE-related CMMRD-like syndrome is unclear. -
Facial dysmorphism-immunodeficiency-livedo-short stature syndrome;CN280943:Familial colorectal cancer Other:1
Variant interpreted as Uncertain significance and reported on 02-11-2020 by Invitae. GenomeConnect-Invitae Patient Insights Network assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. Registry team members make no attempt to reinterpret the clinical significance of the variant. Phenotypic details are available under supporting information. -
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at