2-21001550-C-A

Variant summary

Our verdict is Benign. Variant got -13 ACMG points: 0P and 13B. BP4_Strong BP6 BS1 BS2

The NM_000384.3(APOB):c.*180G>T variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00314 in 604,946 control chromosomes in the GnomAD database, including 21 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.0075 (11 hom., cov: 32)
  • Exomes 𝑓: 0.0017 (10 hom.)
• Consequence: APOB NM_000384.3 3_prime_UTR
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:1
• Conservation: PhyloP100: 0.381

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 Benign. Variant got -13 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.86).
• BP6: Variant 2-21001550-C-A is Benign according to our data. Variant chr2-21001550-C-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 334059.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=1, Likely_benign=1}. Variant chr2-21001550-C-A is described in Lovd as [Likely_benign].
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00749 (1140/152158) while in subpopulation AFR AF= 0.0247 (1024/41502). AF 95% confidence interval is 0.0234. There are 11 homozygotes in gnomad4. There are 558 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 11 SD gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
APOB	NM_000384.3	c.*180G>T		3_prime_UTR_variant	29/29	ENST00000233242.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
APOB	ENST00000233242.5	c.*180G>T		3_prime_UTR_variant	29/29	1	NM_000384.3	P1

Frequencies

GnomAD3 genomes AF: 0.00745 AC: 1132 AN: 152040 Hom.: 11 Cov.: 32

Gnomad AFR AF: 0.0246

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00374

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00891

Gnomad FIN AF: 0.0000945

Gnomad MID AF: 0.00316

Gnomad NFE AF: 0.0000882

Gnomad OTH AF: 0.00383

GnomAD4 exome AF: 0.00168 AC: 760 AN: 452788 Hom.: 10 Cov.: 5 AF XY: 0.00199 AC XY: 474 AN XY: 238522

Gnomad4 AFR exome AF: 0.0240

Gnomad4 AMR exome AF: 0.00215

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00807

Gnomad4 FIN exome AF: 0.000100

Gnomad4 NFE exome AF: 0.000148

Gnomad4 OTH exome AF: 0.00222

GnomAD4 genome AF: 0.00749 AC: 1140 AN: 152158 Hom.: 11 Cov.: 32 AF XY: 0.00750 AC XY: 558 AN XY: 74374

Gnomad4 AFR AF: 0.0247

Gnomad4 AMR AF: 0.00373

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00892

Gnomad4 FIN AF: 0.0000945

Gnomad4 NFE AF: 0.0000882

Gnomad4 OTH AF: 0.00379

Alfa AF: 0.00157 Hom.: 2

Bravo AF: 0.00819

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Familial hypobetalipoproteinemia 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Hypercholesterolemia, autosomal dominant, type B Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.86
Cadd	Benign	0.53
Dann	Benign	0.62
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

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: rs12720763; hg19: chr2-21224422;