rs746085723

Variant names:

• chr6-49453583-A-T
• rs746085723
• NM_000255.4:c.1083+2T>A

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.1083+2T>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000188 in 1,591,744 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 Pathogenic (★★).

• Frequency:
  • Genomes: 𝑓 0.000013 (0 hom., cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: MMUT NM_000255.4 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 8.90
• Publications: 0 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: ClinGen, Labcorp Genetics (formerly Invitae), 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: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 6-49453583-A-T is Pathogenic according to our data. Variant chr6-49453583-A-T is described in ClinVar as Pathogenic. ClinVar VariationId is 495775.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
MMUT	NM_000255.4	c.1083+2T>A		splice_donor_variant, intron_variant	Intron 5 of 12	ENST00000274813.4	NP_000246.2
MMUT	XM_005249143.4	c.1083+2T>A		splice_donor_variant, intron_variant	Intron 5 of 12		XP_005249200.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMUT	ENST00000274813.4	c.1083+2T>A		splice_donor_variant, intron_variant	Intron 5 of 12	1	NM_000255.4	ENSP00000274813.3

Frequencies

GnomAD3 genomes AF: 0.0000132 AC: 2 AN: 151984 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000483

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: 0.00000799 AC: 2 AN: 250466 AF XY: 0.00000738

Gnomad AFR exome AF: 0.000124

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: 6.95e-7 AC: 1 AN: 1439760 Hom.: 0 Cov.: 27 AF XY: 0.00000139 AC XY: 1 AN XY: 717282

African (AFR) AF: 0.0000303 AC: 1 AN: 32962

American (AMR) AF: 0.00 AC: 0 AN: 44586

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25838

East Asian (EAS) AF: 0.00 AC: 0 AN: 39406

South Asian (SAS) AF: 0.00 AC: 0 AN: 84866

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52946

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5710

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1093876

Other (OTH) AF: 0.00 AC: 0 AN: 59570

GnomAD4 genome AF: 0.0000132 AC: 2 AN: 151984 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74254

African (AFR) AF: 0.0000483 AC: 2 AN: 41400

American (AMR) AF: 0.00 AC: 0 AN: 15272

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5198

South Asian (SAS) AF: 0.00 AC: 0 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10488

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68012

Other (OTH) AF: 0.00 AC: 0 AN: 2088

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:1

Oct 15, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 5 of the MUT gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in MUT are known to be pathogenic (PMID: 15781192). This variant is present in population databases (rs746085723, gnomAD 0.01%). Disruption of this splice site has been observed in individual(s) with methylmalonic acidemia (PMID: 16281286). ClinVar contains an entry for this variant (Variation ID: 495775). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Methylmalonic acidemia Pathogenic:1

Oct 24, 2016

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The MUT c.1083+2T>A variant involves the alteration of the GT donor splice site of intron 5, which 5/5 splice prediction tools predict abrogation of the donor site. This variant was found in 1/119390 control chromosomes at a frequency of 0.0000084, which does not exceed the estimated maximal expected allele frequency of a pathogenic MUT variant (0.0024152). This variant has been reported in one patient with Methylmalonic Acidemia who was compound heterozygous with another variant c.1328dupT. Taken together, this variant is classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Uncertain	0.050
CADD	Pathogenic	29
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.96
FATHMM_MKL	Pathogenic	0.97	D
PhyloP100		8.9
GERP RS		5.8
Mutation Taster		=7/92	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.92
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.99		Position offset: 2

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

Other links and lift over

dbSNP: rs746085723; hg19: chr6-49421296;