NM_000255.4:c.1420C>T

Variant names:

• chr6-49448840-G-A
• rs887126161
• NM_000255.4:c.1420C>T

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000255.4(MMUT):​c.1420C>T​(p.Arg474*) variant causes a stop gained change. The variant allele was found at a frequency of 0.00000753 in 1,461,044 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000075 (0 hom.)
• Consequence: MMUT NM_000255.4 stop_gained
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:8
• Conservation: PhyloP100: 6.52
• Publications: 4 publications found

Genes affected

MMUT (HGNC:7526): (methylmalonyl-CoA mutase) This gene encodes the mitochondrial enzyme methylmalonyl Coenzyme A mutase. In humans, the product of this gene is a vitamin B12-dependent enzyme which catalyzes the isomerization of methylmalonyl-CoA to succinyl-CoA, while in other species this enzyme may have different functions. Mutations in this gene may lead to various types of methylmalonic aciduria. [provided by RefSeq, Jul 2008]

MMUT Gene-Disease associations (from GenCC):

• methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, G2P
• vitamin B12-unresponsive methylmalonic acidemia type mut-

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• vitamin B12-unresponsive methylmalonic acidemia type mut0

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 18 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 6-49448840-G-A is Pathogenic according to our data. Variant chr6-49448840-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 554873.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000255.4. 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
	MMUT	NM_000255.4	MANE Select	c.1420C>T	p.Arg474*	stop_gained	Exon 7 of 13	NP_000246.2	P22033

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	MMUT	ENST00000274813.4	TSL:1 MANE Select	c.1420C>T	p.Arg474*	stop_gained	Exon 7 of 13	ENSP00000274813.3	P22033
	MMUT	ENST00000878060.1		c.1420C>T	p.Arg474*	stop_gained	Exon 7 of 13	ENSP00000548119.1
	MMUT	ENST00000878062.1		c.1420C>T	p.Arg474*	stop_gained	Exon 7 of 13	ENSP00000548121.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000796 AC: 2 AN: 251244 AF XY: 0.00

Gnomad AFR exome AF: 0.00

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: 0.00000880

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000753 AC: 11 AN: 1461044 Hom.: 0 Cov.: 30 AF XY: 0.00000550 AC XY: 4 AN XY: 726872

African (AFR) AF: 0.0000299 AC: 1 AN: 33432

American (AMR) AF: 0.00 AC: 0 AN: 44712

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26110

East Asian (EAS) AF: 0.00 AC: 0 AN: 39626

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86220

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53412

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

European-Non Finnish (NFE) AF: 0.00000720 AC: 8 AN: 1111408

Other (OTH) AF: 0.00 AC: 0 AN: 60358

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.00000756

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
2	-	-	Methylmalonic aciduria due to methylmalonyl-CoA mutase deficiency (2)
1	-	-	Likely inborn error of metabolism (1)
1	-	-	Methylmalonic acidemia (1)
1	-	-	Methylmalonic aciduria (1)
1	-	-	Methylmalonic aciduria due to complete methylmalonyl-CoA mutase deficiency (1)
1	-	-	MMUT-related disorder (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.56	D
BayesDel_noAF	Pathogenic	0.65
CADD	Pathogenic	40
DANN	Uncertain	1.0
Eigen	Pathogenic	0.86
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		6.5
Vest4		0.97
GERP RS		5.1
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: rs887126161; hg19: chr6-49416553;