5-112766410-G-C

Position:

• chr5-112766410-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PM5

The NM_000038.6(APC):​c.220G>C​(p.Glu74Gln) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E74K) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: APC NM_000038.6 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 8.68

Genes affected

APC (HGNC:583): (APC regulator of WNT signaling pathway) This gene encodes a tumor suppressor protein that acts as an antagonist of the Wnt signaling pathway. It is also involved in other processes including cell migration and adhesion, transcriptional activation, and apoptosis. Defects in this gene cause familial adenomatous polyposis (FAP), an autosomal dominant pre-malignant disease that usually progresses to malignancy. Mutations in the APC gene have been found to occur in most colorectal cancers, where disease-associated mutations tend to be clustered in a small region designated the mutation cluster region (MCR) and result in a truncated protein product. [provided by RefSeq, Jun 2022]

APC (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr5-112766410-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
APC	NM_000038.6	c.220G>C	p.Glu74Gln	missense_variant, splice_region_variant	3/16	ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9	c.220G>C	p.Glu74Gln	missense_variant, splice_region_variant	3/16	5	NM_000038.6	ENSP00000257430.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 27

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Jan 16, 2021

Variant summary: APC c.220G>C (p.Glu74Gln), located in the exonic splice region as the last nucleotide alteration of APC exon 3, results in a conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a benign effect of the variant on protein function. Several computational tools predict a significant impact on normal splicing: Four predict the variant abolishes the canonical 5' splicing donor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 250308 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.220G>C in individuals affected with Familial Adenomatous Polyposis and no experimental evidence demonstrating its impact on protein function have been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as uncertain significance based upon identical ascertainment criteria. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Familial adenomatous polyposis 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 13, 2020

In summary, this is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. Nucleotide substitutions within the consensus splice site are relatively common causes of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of nucleotide changes on RNA splicing suggest that this variant may alter RNA splicing, but this prediction has not been confirmed by published transcriptional studies. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a APC-related disease. This sequence change replaces glutamic acid with glutamine at codon 74 of the APC protein (p.Glu74Gln). The glutamic acid residue is highly conserved and there is a small physicochemical difference between glutamic acid and glutamine. This variant also falls at the last nucleotide of exon 3 of the APC coding sequence, which is part of the consensus splice site for this exon. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.25
BayesDel_addAF	Uncertain	0.12	D
BayesDel_noAF	Uncertain	-0.060
CADD	Pathogenic	35
DANN	Uncertain	1.0
DEOGEN2	Benign	0.31	T;.;D;D;T
Eigen	Uncertain	0.44
Eigen_PC	Uncertain	0.52
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.95	D;D;.;D;D
MetaRNN	Benign	0.27	T;T;T;T;T
MetaSVM	Uncertain	0.17	D
MutationAssessor	Benign	1.8	.;.;L;L;.
PrimateAI	Uncertain	0.62	T
PROVEAN	Benign	-1.2	N;N;N;N;N
REVEL	Benign	0.20
Sift	Benign	0.11	T;D;T;T;D
Sift4G	Uncertain	0.038	D;T;T;T;T
Polyphen		0.86	.;.;P;P;.
Vest4		0.62, 0.61
MutPred		0.10		Gain of MoRF binding (P = 0.0542);.;Gain of MoRF binding (P = 0.0542);Gain of MoRF binding (P = 0.0542);Gain of MoRF binding (P = 0.0542);
MVP		0.82
ClinPred		0.90	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.8
Varity_R		0.22
gMVP		0.30

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.90		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.69		Position offset: 15
DS_DL_spliceai		0.90		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs876658941; hg19: chr5-112102107;