chr2-21015152-A-G

Position:

• chr2-21015152-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000384.3(APOB):​c.3617T>C​(p.Met1206Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,864 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 14/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: APOB NM_000384.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.458

Genes affected

APOB (HGNC:603): (apolipoprotein B) This gene product is the main apolipoprotein of chylomicrons and low density lipoproteins (LDL), and is the ligand for the LDL receptor. It occurs in plasma as two main isoforms, apoB-48 and apoB-100: the former is synthesized exclusively in the gut and the latter in the liver. The intestinal and the hepatic forms of apoB are encoded by a single gene from a single, very long mRNA. The two isoforms share a common N-terminal sequence. The shorter apoB-48 protein is produced after RNA editing of the apoB-100 transcript at residue 2180 (CAA->UAA), resulting in the creation of a stop codon, and early translation termination. Mutations in this gene or its regulatory region cause hypobetalipoproteinemia, normotriglyceridemic hypobetalipoproteinemia, and hypercholesterolemia due to ligand-defective apoB, diseases affecting plasma cholesterol and apoB levels. [provided by RefSeq, Dec 2019]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.1375952).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APOB	NM_000384.3	c.3617T>C	p.Met1206Thr	missense_variant	23/29	ENST00000233242.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APOB	ENST00000233242.5	c.3617T>C	p.Met1206Thr	missense_variant	23/29	1	NM_000384.3	P1
APOB	ENST00000673739.2	c.*2923T>C		3_prime_UTR_variant, NMD_transcript_variant	22/25
APOB	ENST00000673882.2	c.*2712T>C		3_prime_UTR_variant, NMD_transcript_variant	21/23

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461864 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 727240

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: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Hypercholesterolemia, autosomal dominant, type B;C4551990:Familial hypobetalipoproteinemia 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 09, 2016

This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a APOB-related disease. In summary, this is a novel missense change that is not predicted to affect protein function or cause disease. However, the evidence is insufficient at this time to prove that conclusively. It has been classified as a Variant of Uncertain Significance. The threonine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. In addition, algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies. This sequence change replaces methionine with threonine at codon 1206 of the APOB protein (p.Met1206Thr). The methionine residue is weakly conserved and there is a moderate physicochemical difference between methionine and threonine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.066
BayesDel_addAF	Benign	-0.44	T
BayesDel_noAF	Benign	-0.86
CADD	Benign	0.0020
DANN	Benign	0.23
Eigen	Benign	-1.8
Eigen_PC	Benign	-1.9
FATHMM_MKL	Benign	0.17	N
M_CAP	Benign	0.0075	T
MetaRNN	Benign	0.14	T
MetaSVM	Benign	-0.91	T
MutationTaster	Benign	1.0	N
PrimateAI	Benign	0.22	T
PROVEAN	Benign	-0.44	N
REVEL	Benign	0.024
Sift	Benign	0.55	T
Sift4G	Benign	0.28	T
Vest4		0.020
MutPred		0.28		Gain of ubiquitination at K1202 (P = 0.1215);
MVP		0.23
MPC		0.040
ClinPred		0.032	T
GERP RS		-11
gMVP		0.22

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: rs878853972; hg19: chr2-21238024;