dbSNP rs140522266: MMACHC:p.Gly147Asp (chr1-45508806-G-A) – ACMG Classification: Pathogenic (23 pts)

Variant summary

Our verdict is Pathogenic. The variant received 23 ACMG points: 23P and 0B. PS3PM1PM2PM5PP2PP3_StrongPP5_Very_Strong

The NM_015506.3(MMACHC):c.440G>A(p.Gly147Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000496 in 1,613,972 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 Likely pathogenic (★★). ClinVar reports functional evidence for this variant: "SCV000699399: "In addition, p.Gly147Ala is also classified as pathogenic in ClinVar, suggesting Gly147 is critical for MMACHC function, which is confirmed by a functional study showed that G147D mutation was unable to bind either hydroxyl form of vitamin B12 (OHCbl) or cyano derivative (CNCbl)."" and additional evidence is available in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G147A) has been classified as Likely pathogenic.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000048 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 missense

Scores

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:10

Conservation

PhyloP100: 9.36

Publications

23 publications found

Variant links:

Genes affected

MMACHC (HGNC:24525): (metabolism of cobalamin associated C) The exact function of the protein encoded by this gene is not known, however, its C-terminal region shows similarity to TonB, a bacterial protein involved in energy transduction for cobalamin (vitamin B12) uptake. Hence, it is postulated that this protein may have a role in the binding and intracellular trafficking of cobalamin. Mutations in this gene are associated with methylmalonic aciduria and homocystinuria type cblC. [provided by RefSeq, Oct 2009]

MMACHC Gene-Disease associations (from GenCC):

methylmalonic aciduria and homocystinuria type cblC
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, ClinGen, Labcorp Genetics (formerly Invitae), Ambry Genetics, Myriad Women’s Health

MMACHC links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 23 ACMG points.

PS3

PS3 evidence extracted from ClinVar submissions: SCV000699399: "In addition, p.Gly147Ala is also classified as pathogenic in ClinVar, suggesting Gly147 is critical for MMACHC function, which is confirmed by a functional study showed that G147D mutation was unable to bind either hydroxyl form of vitamin B12 (OHCbl) or cyano derivative (CNCbl)."; SCV000762775: Experimental studies have shown that this missense change affects MMACHC function (PMID: 19700356).

PM1

In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 6 uncertain in NM_015506.3

PM2

Very rare variant in population databases, with high coverage;

PM5

Other missense variant is known to change same aminoacid residue: Variant chr1-45508806-G-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 203828.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

PP2

Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 28 curated pathogenic missense variants (we use a threshold of 10). The gene has 7 curated benign missense variants. Gene score misZ: -1.0759 (below the threshold of 3.09). Trascript score misZ: -0.13772 (below the threshold of 3.09). GenCC associations: The gene is linked to methylmalonic aciduria and homocystinuria type cblC.

PP3

MetaRNN computational evidence supports a deleterious effect, 0.99

PP5

Variant 1-45508806-G-A is Pathogenic according to our data. Variant chr1-45508806-G-A is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 203829.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_015506.3. 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
	MMACHC	NM_015506.3	MANE Select	c.440G>A	p.Gly147Asp	missense	Exon 4 of 4	NP_056321.2	Q9Y4U1
	MMACHC	NM_001330540.2		c.269G>A	p.Gly90Asp	missense	Exon 4 of 4	NP_001317469.1	A0A0C4DGU2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
MMACHC	ENST00000401061.9	TSL:2 MANE Select	c.440G>A	p.Gly147Asp	missense	Exon 4 of 4	ENSP00000383840.4	Q9Y4U1
MMACHC	ENST00000616135.1	TSL:2	c.269G>A	p.Gly90Asp	missense	Exon 4 of 5	ENSP00000478859.1	A0A0C4DGU2
MMACHC	ENST00000933807.1		c.245G>A	p.Gly82Asp	missense	Exon 3 of 3	ENSP00000603866.1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152178

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000161

AC:

AN:

248850

AF XY:

0.0000148

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000291

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000266

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000479

AC:

AN:

1461678

Hom.:

Cov.:

AF XY:

0.00000550

AC XY:

AN XY:

727128

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33476

American (AMR)

AF:

0.0000448

AC:

AN:

44666

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26120

East Asian (EAS)

AF:

0.0000756

AC:

AN:

39696

South Asian (SAS)

AF:

0.00

AC:

AN:

86226

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53416

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00000180

AC:

AN:

1111920

Other (OTH)

AF:

0.00

AC:

AN:

60392

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.468

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:

0.00000657

AC:

AN:

152294

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74462

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41556

American (AMR)

AF:

0.00

AC:

AN:

15298

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5182

South Asian (SAS)

AF:

0.000207

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10612

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68030

Other (OTH)

AF:

0.00

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

ExAC

AF:

0.0000248

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

EpiCase

AF:

0.00

EpiControl

AF:

0.000119

ClinVar

ClinVar submissions

Significance:Pathogenic/Likely pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

Cobalamin C disease (8)

Methylmalonic acidemia with homocystinuria cblC (1)

not provided (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.96

BayesDel_addAF

Pathogenic

0.50

BayesDel_noAF

Pathogenic

0.57

CADD

Uncertain

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.93

Eigen

Pathogenic

0.92

Eigen_PC

Pathogenic

0.89

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Benign

0.81

M_CAP

Pathogenic

0.52

MetaRNN

Pathogenic

0.99

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.3

PhyloP100

9.4

PrimateAI

Uncertain

0.70

PROVEAN

Pathogenic

-6.2

REVEL

Pathogenic

0.95

Sift

Uncertain

0.0020

Sift4G

Pathogenic

0.0

Polyphen

0.99

Vest4

0.94

MutPred

0.96

Loss of glycosylation at S146 (P = 0.0328)

MVP

0.98

MPC

0.079

ClinPred

0.97

GERP RS

5.6

Varity_R

0.95

gMVP

0.98

Mutation Taster

=2/98

disease causing (ClinVar)

(source)

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over