rs121965014

Variant names:

• chr22-42630986-G-A
• rs121965014
• NM_000398.7:c.229C>T

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000398.7(CYB5R3):​c.229C>T​(p.Gln77*) variant causes a stop gained, splice region change. The variant allele was found at a frequency of 0.000000684 in 1,461,384 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CYB5R3 NM_000398.7 stop_gained, splice_region
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 5.41
• Publications: 2 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

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 22-42630986-G-A is Pathogenic according to our data. Variant chr22-42630986-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 247.Status of the report is criteria_provided_single_submitter, 1 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.229C>T	p.Gln77*	stop_gained splice_region	Exon 4 of 9	NP_000389.1	P00387-1
	CYB5R3	NM_001171660.2		c.328C>T	p.Gln110*	stop_gained splice_region	Exon 4 of 9	NP_001165131.1	P00387-3
	CYB5R3	NM_001129819.2		c.160C>T	p.Gln54*	stop_gained splice_region	Exon 4 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.229C>T	p.Gln77*	stop_gained splice_region	Exon 4 of 9	ENSP00000338461.6	P00387-1
	CYB5R3	ENST00000407332.6	TSL:1	c.247C>T	p.Gln83*	stop_gained splice_region	Exon 4 of 9	ENSP00000384457.2	A0A8J8Z3C6
	CYB5R3	ENST00000470741.1	TSL:1	n.2363C>T		non_coding_transcript_exon	Exon 1 of 6

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461384 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726934

African (AFR) AF: 0.00 AC: 0 AN: 33474

American (AMR) AF: 0.00 AC: 0 AN: 44688

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26114

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86124

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53340

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111800

Other (OTH) AF: 0.00 AC: 0 AN: 60380

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
1	-	-	METHEMOGLOBINEMIA, TYPE II (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.62	D
BayesDel_noAF	Pathogenic	0.65
CADD	Pathogenic	45
DANN	Uncertain	1.0
Eigen	Pathogenic	0.76
Eigen_PC	Uncertain	0.58
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		5.4
Vest4		0.92
GERP RS		3.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Mutation Taster		=0/200	disease causing (ClinVar)

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: rs121965014; hg19: chr22-43026992;