19-40846953-C-T

Variant names:

• chr19-40846953-C-T
• rs374784083
• NM_000762.6:c.753G>A

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 2P and 3B. PM2 BP4_Moderate BP7

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
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.418
• Publications: 1 publications found

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)

ENSG00000268797 (HGNC:):

ACMG classification

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.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000762.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CYP2A6	NM_000762.6	MANE Select	c.753G>A	p.Lys251Lys	synonymous	Exon 5 of 9	NP_000753.3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CYP2A6	ENST00000301141.10	TSL:1 MANE Select	c.753G>A	p.Lys251Lys	synonymous	Exon 5 of 9	ENSP00000301141.4	P11509
	CYP2A6	ENST00000596719.5	TSL:1	n.604G>A		non_coding_transcript_exon	Exon 4 of 6
	CYP2A6	ENST00000600495.1	TSL:1	n.*565G>A		non_coding_transcript_exon	Exon 5 of 6	ENSP00000472905.1	M0R2Z4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1460256 Hom.: 0 Cov.: 31 AF XY: 0.00000551 AC XY: 4 AN XY: 726434

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

African (AFR) AF: 0.00 AC: 0 AN: 33456

American (AMR) AF: 0.00 AC: 0 AN: 44714

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.0000260 AC: 1 AN: 38438

South Asian (SAS) AF: 0.0000348 AC: 3 AN: 86150

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53370

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111950

Other (OTH) AF: 0.00 AC: 0 AN: 60280

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0000000286219), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000113

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.43
CADD	Benign	5.4
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

Other links and lift over

dbSNP: rs374784083; hg19: chr19-41352858;