5-112840492-C-A

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_000038.6(APC):c.4898C>A(p.Thr1633Lys) 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 1,461,864 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. T1633I) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

APC
NM_000038.6 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:4

Conservation

PhyloP100: 3.43

Publications

4 publications found

Variant links:

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 Gene-Disease associations (from GenCC):

classic or attenuated familial adenomatous polyposis
Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
desmoid tumor
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp
familial adenomatous polyposis 1
Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Ambry Genetics
gastric adenocarcinoma and proximal polyposis of the stomach
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), ClinGen, Orphanet
sarcoma
Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
APC-related attenuated familial adenomatous polyposis
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Turcot syndrome with polyposis
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Cenani-Lenz syndactyly syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

APC links:

ENSG00000258864 (HGNC:):

ENSG00000258864 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
APC	NM_000038.6 link	c.4898C>A	p.Thr1633Lys	missense_variant	Exon 16 of 16	ENST00000257430.9	NP_000029.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
APC	ENST00000257430.9 link	c.4898C>A	p.Thr1633Lys	missense_variant	Exon 16 of 16	5	NM_000038.6	ENSP00000257430.4
ENSG00000258864	ENST00000520401.1 link	n.228+11520C>A		intron_variant	Intron 3 of 7	3		ENSP00000454861.1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461864

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727236

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26134

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111988

Other (OTH)

AF:

0.00

AC:

AN:

60392

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.375

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

Alfa

AF:

0.00

Hom.:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:2

Nov 27, 2023

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant does not alter protein structure/function; Observed only in unaffected controls is a study of individuals with colorectal adenomas (PMID: 18199528); This variant is associated with the following publications: (PMID: 18199528) -

Dec 01, 2023

CeGaT Center for Human Genetics Tuebingen

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

APC: PM2 -

Familial adenomatous polyposis 1

Uncertain:1

Apr 22, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces threonine, which is neutral and polar, with lysine, which is basic and polar, at codon 1633 of the APC protein (p.Thr1633Lys). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with APC-related conditions. ClinVar contains an entry for this variant (Variation ID: 537555). 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 APC protein function with a negative predictive value of 95%. 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. -

Hereditary cancer-predisposing syndrome

Uncertain:1

May 30, 2023

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The p.T1633K variant (also known as c.4898C>A), located in coding exon 15 of the APC gene, results from a C to A substitution at nucleotide position 4898. The threonine at codon 1633 is replaced by lysine, an amino acid with similar properties. This alteration was not observed in 691 North American patients with colorectal adenomas, but was observed in 1/969 matched healthy controls (Azzopardi D et al. Cancer Res. 2008 Jan; 68(2):358-63). This amino acid position is well conserved in available vertebrate species. In addition, in silico predictors for this gene do not accurately predict pathogenicity. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.38

BayesDel_addAF

Pathogenic

0.21

BayesDel_noAF

Uncertain

0.060

CADD

Uncertain

(source)

DANN

Benign

0.97

DEOGEN2

Uncertain

0.46

T;T

Eigen

Uncertain

0.29

Eigen_PC

Uncertain

0.41

FATHMM_MKL

Uncertain

0.90

LIST_S2

Benign

0.81

.;T

M_CAP

Benign

0.052

MetaRNN

Uncertain

0.73

D;D

MetaSVM

Uncertain

-0.037

MutationAssessor

Benign

0.55

N;N

PhyloP100

3.4

PrimateAI

Uncertain

0.60

PROVEAN

Benign

-0.87

N;N

REVEL

Uncertain

0.52

Sift

Benign

0.063

T;T

Sift4G

Benign

0.092

T;T

Polyphen

0.84

P;P

Vest4

0.67

MutPred

0.38

Gain of methylation at T1633 (P = 0.0055);Gain of methylation at T1633 (P = 0.0055);

MVP

0.93

ClinPred

0.47

GERP RS

5.6

Varity_R

0.23

gMVP

0.58

Mutation Taster

=39/61

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over