Genetic Variant CYP2A6:p.Lys251Lys (chr19-40846953-C-T) – ACMG Classification: Likely_benign (-1 pts)

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2BP4_ModerateBP7

The NM_000762.6(CYP2A6):c.753G>A(p.Lys251Lys) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,460,256 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000027 ( 0 hom. )

Consequence

CYP2A6
NM_000762.6 synonymous

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -0.418

Publications

1 publications found

Variant links:

Genes affected

CYP2A6 (HGNC:2610): (cytochrome P450 family 2 subfamily A member 6) This gene, CYP2A6, encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This protein localizes to the endoplasmic reticulum and its expression is induced by phenobarbital. The enzyme is known to hydroxylate coumarin, and also metabolizes nicotine, aflatoxin B1, nitrosamines, and some pharmaceuticals. Individuals with certain allelic variants are said to have a poor metabolizer phenotype, meaning they do not efficiently metabolize coumarin or nicotine. This gene is part of a large cluster of cytochrome P450 genes from the CYP2A, CYP2B and CYP2F subfamilies on chromosome 19q. The gene was formerly referred to as CYP2A3; however, it has been renamed CYP2A6. [provided by RefSeq, Jul 2008]

CYP2A6 Gene-Disease associations (from GenCC):

coumarin resistance
Inheritance: Unknown Classification: NO_KNOWN Submitted by: Labcorp Genetics (formerly Invitae)
nicotine dependence
Inheritance: Unknown Classification: NO_KNOWN Submitted by: Labcorp Genetics (formerly Invitae)

CYP2A6 links:

ENSG00000268797 (HGNC:):

ENSG00000268797 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.43).

BP7

Synonymous conserved (PhyloP=-0.418 with no splicing effect.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CYP2A6	NM_000762.6 link	c.753G>A	p.Lys251Lys	synonymous_variant	Exon 5 of 9	ENST00000301141.10	NP_000753.3	P11509

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CYP2A6	ENST00000301141.10 link	c.753G>A	p.Lys251Lys	synonymous_variant	Exon 5 of 9	1	NM_000762.6	ENSP00000301141.4		P11509
ENSG00000268797	ENST00000601627.1 link	n.118-45038C>T		intron_variant	Intron 1 of 3	3		ENSP00000469533.1		M0QY20

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

0.00000274

AC:

AN:

1460256

Hom.:

Cov.:

AF XY:

0.00000551

AC XY:

AN XY:

726434

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:

33456

American (AMR)

AF:

0.00

AC:

AN:

44714

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.0000260

AC:

AN:

38438

South Asian (SAS)

AF:

0.0000348

AC:

AN:

86150

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53370

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111950

Other (OTH)

AF:

0.00

AC:

AN:

60280

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.388

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.:

Bravo

AF:

0.0000113

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.43

CADD

Benign

5.4

(source)

DANN

Benign

0.62

PhyloP100

-0.42

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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19-40846953-C-T

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over