NM_000398.7:c.757G>C

Variant names:

• chr22-42619922-C-G
• rs144071404
• NM_000398.7:c.757G>C

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PM5

The NM_000398.7(CYB5R3):​c.757G>C​(p.Val253Leu) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V253M) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: CYB5R3 NM_000398.7 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.50
• Publications: 0 publications found

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: DEFINITIVE, STRONG Submitted by: G2P, ClinGen, Labcorp Genetics (formerly Invitae)
• hereditary methemoglobinemia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ENSG00000289517 (HGNC:):

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr22-42619922-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 505719.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000398.7. 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
	CYB5R3	NM_000398.7	MANE Select	c.757G>C	p.Val253Leu	missense	Exon 9 of 9	NP_000389.1	P00387-1
	CYB5R3	NM_001171660.2		c.856G>C	p.Val286Leu	missense	Exon 9 of 9	NP_001165131.1	P00387-3
	CYB5R3	NM_001129819.2		c.688G>C	p.Val230Leu	missense	Exon 9 of 9	NP_001123291.1	P00387-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CYB5R3	ENST00000352397.10	TSL:1 MANE Select	c.757G>C	p.Val253Leu	missense	Exon 9 of 9	ENSP00000338461.6	P00387-1
	CYB5R3	ENST00000407332.6	TSL:1	c.775G>C	p.Val259Leu	missense	Exon 9 of 9	ENSP00000384457.2	A0A8J8Z3C6
	CYB5R3	ENST00000470741.1	TSL:1	n.2891G>C		non_coding_transcript_exon	Exon 6 of 6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.60
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Benign	0.33	T
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.51
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Benign	0.85	T
M_CAP	Uncertain	0.18	D
MetaRNN	Uncertain	0.67	D
MetaSVM	Pathogenic	0.81	D
MutationAssessor	Uncertain	2.7	M
PhyloP100		4.5
PrimateAI	Uncertain	0.66	T
PROVEAN	Uncertain	-2.4	N
REVEL	Pathogenic	0.77
Sift	Uncertain	0.0030	D
Sift4G	Uncertain	0.031	D
Polyphen		0.37	B
Vest4		0.50
MutPred		0.70		Loss of catalytic residue at V253 (P = 0.0382)
MVP		0.97
MPC		0.16
ClinPred		0.92	D
GERP RS		4.6
Varity_R		0.82
gMVP		0.60
Mutation Taster		=25/75	disease causing

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: rs144071404; hg19: chr22-43015928;