5-112835024-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1 PP3_Moderate

The NM_000038.6(APC):c.1817T>C(p.Ile606Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,830 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 Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I606M) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: APC NM_000038.6 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.67

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM1: In a repeat ARM 4 (size 46) in uniprot entity APC_HUMAN there are 7 pathogenic changes around while only 1 benign (88%) in NM_000038.6
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.871

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APC	NM_000038.6	c.1817T>C	p.Ile606Thr	missense_variant	15/16	ENST00000257430.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APC	ENST00000257430.9	c.1817T>C	p.Ile606Thr	missense_variant	15/16	5	NM_000038.6	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251298 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135808

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000479 AC: 7 AN: 1461830 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727216

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial adenomatous polyposis 1 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Jun 22, 2023	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Oct 20, 2023	This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 606 of the APC protein (p.Ile606Thr). This variant is present in population databases (rs781337455, gnomAD 0.0009%). 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: 537509). 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. 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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 18, 2023

The p.I606T variant (also known as c.1817T>C), located in coding exon 14 of the APC gene, results from a T to C substitution at nucleotide position 1817. The isoleucine at codon 606 is replaced by threonine, an amino acid with similar properties. This alteration was also detected on a 25-gene panel test in a woman of Western/Northern European ancestry who was diagnosed with breast cancer before age 50 (Tung N et al. Cancer, 2015 Jan;121:25-33). This amino acid position is highly 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	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.37	D
BayesDel_noAF	Pathogenic	0.30
Cadd	Pathogenic	27
Dann	Uncertain	1.0
Eigen	Pathogenic	0.87
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D;.;D;D;D
M_CAP	Uncertain	0.086	D
MetaRNN	Pathogenic	0.87	D;D;D;D;D
MetaSVM	Uncertain	0.099	D
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.92	D
PROVEAN	Pathogenic	-4.5	D;D;D;D;.
REVEL	Pathogenic	0.81
Sift	Uncertain	0.015	D;D;D;D;.
Sift4G	Uncertain	0.0020	D;D;D;D;D
Polyphen		1.0	.;D;D;.;.
Vest4		0.98, 0.96
MutPred		0.75		.;Gain of disorder (P = 0.0278);Gain of disorder (P = 0.0278);Gain of disorder (P = 0.0278);.;
MVP		0.95
ClinPred		0.98	D
GERP RS		5.9
Varity_R		0.85
gMVP		0.79

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

LitVar

Other links and lift over

dbSNP: rs781337455; hg19: chr5-112170721; COSMIC: COSV57326533;