NM_000398.7:c.464-2A>C

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1_ModeratePP5_Very_Strong

The NM_000398.7(CYB5R3):c.464-2A>C variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000745 in 1,610,050 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000055 ( 0 hom. )

Consequence

CYB5R3
NM_000398.7 splice_acceptor, intron

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6

Conservation

PhyloP100: 7.98

Publications

0 publications found

Variant links:

Genes affected

CYB5R3 (HGNC:2873): (cytochrome b5 reductase 3) This gene encodes cytochrome b5 reductase, which includes a membrane-bound form in somatic cells (anchored in the endoplasmic reticulum, mitochondrial and other membranes) and a soluble form in erythrocytes. The membrane-bound form exists mainly on the cytoplasmic side of the endoplasmic reticulum and functions in desaturation and elongation of fatty acids, in cholesterol biosynthesis, and in drug metabolism. The erythrocyte form is located in a soluble fraction of circulating erythrocytes and is involved in methemoglobin reduction. The membrane-bound form has both membrane-binding and catalytic domains, while the soluble form has only the catalytic domain. Alternate splicing results in multiple transcript variants. Mutations in this gene cause methemoglobinemias. [provided by RefSeq, Jan 2010]

CYB5R3 Gene-Disease associations (from GenCC):

methemoglobinemia
Inheritance: AR Classification: DEFINITIVE Submitted by: Illumina
methemoglobinemia due to deficiency of methemoglobin reductase
Inheritance: AR Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
hereditary methemoglobinemia
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

CYB5R3 links:

ENSG00000289517 (HGNC:):

ENSG00000289517 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 10 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.09271523 fraction of the gene. Cryptic splice site detected, with MaxEntScore 5.3, offset of 5, new splice context is: cttctctctcccccgggaAGttc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.

PP5

Variant 22-42627690-T-G is Pathogenic according to our data. Variant chr22-42627690-T-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 245.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CYB5R3	NM_000398.7 link	c.464-2A>C		splice_acceptor_variant, intron_variant	Intron 5 of 8	ENST00000352397.10	NP_000389.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CYB5R3	ENST00000352397.10 link	c.464-2A>C		splice_acceptor_variant, intron_variant	Intron 5 of 8	1	NM_000398.7	ENSP00000338461.6
ENSG00000289517	ENST00000617178.5 link	n.-4A>C		upstream_gene_variant		1		ENSP00000482500.2

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

151992

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000967

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000795

AC:

AN:

251442

AF XY:

0.00000736

show subpopulations

Gnomad AFR exome

AF:

0.000123

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000549

AC:

AN:

1458058

Hom.:

Cov.:

AF XY:

0.00000413

AC XY:

AN XY:

725664

show subpopulations

African (AFR)

AF:

0.000240

AC:

AN:

33368

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26118

East Asian (EAS)

AF:

0.00

AC:

AN:

39686

South Asian (SAS)

AF:

0.00

AC:

AN:

86192

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53412

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1108516

Other (OTH)

AF:

0.00

AC:

AN:

60284

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.463

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000263

AC:

AN:

151992

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74264

show subpopulations

African (AFR)

AF:

0.0000967

AC:

AN:

41356

American (AMR)

AF:

0.00

AC:

AN:

15260

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5178

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10606

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67982

Other (OTH)

AF:

0.00

AC:

AN:

2086

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.663

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000329

Hom.:

Bravo

AF:

0.0000529

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Deficiency of cytochrome-b5 reductase

Pathogenic:3

May 28, 2019

Mendelics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Feb 19, 2024

Revvity Omics, Revvity

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Jul 05, 2022

Laboratorio de Genetica e Diagnostico Molecular, Hospital Israelita Albert Einstein

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

ACMG classification criteria: PVS1 very strong, PS3 supporting, PS4 moderated, PM2 moderated, PM3 moderated, PP4

not provided

Pathogenic:2

Dec 12, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change affects an acceptor splice site in intron 5 of the CYB5R3 gene. RNA analysis indicates that disruption of this splice site induces altered splicing and likely results in a shortened protein product. This variant is present in population databases (rs794728013, gnomAD 0.02%). Disruption of this splice site has been observed in individuals with methemoglobinemia (PMID: 9266404; internal data). ClinVar contains an entry for this variant (Variation ID: 245). Studies have shown that disruption of this splice site results in skipping of exon 6, but is expected to preserve the integrity of the reading-frame (PMID: 9266404). For these reasons, this variant has been classified as Pathogenic.

May 05, 2022

GeneDx

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Canonical splice site variant expected to result in aberrant splicing, and in vitro studies demonstrate altered splicing (Maran et al., 2005); This variant is associated with the following publications: (PMID: 31898843, 25525159, 15921385, 15744830, 9266404)

METHEMOGLOBINEMIA, TYPE II

Pathogenic:1

May 01, 2005

OMIM

Significance:Pathogenic

Review Status:no assertion criteria provided

Collection Method:literature only

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.45

BayesDel_noAF

Pathogenic

0.35

CADD

Pathogenic

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.0

.;.;.;.;.;.

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

0.87

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Benign

0.0

.;.;.;.;.;.

MetaRNN

Benign

0.0

.;.;.;.;.;.

MutationAssessor

Benign

0.0

.;.;.;.;.;.

PhyloP100

8.0

PROVEAN

Benign

0.0

.;.;.;.;.;.

REVEL

Benign

0.0

Sift

Pathogenic

0.0

.;.;.;.;.;.

Sift4G

Pathogenic

0.0

.;.;.;.;.;.

Vest4

0.0

GERP RS

4.3

Mutation Taster

=0/100

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.93

SpliceAI score (max)

0.99

Details are displayed if max score is > 0.2

DS_AL_spliceai

0.99

Position offset: -2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over