Genetic Variant MMACHC:p.Arg206Trp (chr1-45508982-C-T) – ACMG Classification: Pathogenic (19 pts)

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1PM2PM5PP2PP3_StrongPP5_Very_Strong

The NM_015506.3(MMACHC):c.616C>T(p.Arg206Trp) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000682 in 1,614,050 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R206P) has been classified as Likely pathogenic.

Frequency

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

Exomes 𝑓: 0.0000068 ( 0 hom. )

Consequence

MMACHC
NM_015506.3 missense

Scores

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:5U:1

Conservation

PhyloP100: -0.0290

Publications

14 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 19 ACMG points.

PM1

In a chain Cyanocobalamin reductase / alkylcobalamin dealkylase (size 281) in uniprot entity MMAC_HUMAN there are 42 pathogenic changes around while only 16 benign (72%) 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 chr1-45508983-G-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 558321.

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, 0.992

PP5

Variant 1-45508982-C-T is Pathogenic according to our data. Variant chr1-45508982-C-T is described in ClinVar as Pathogenic. ClinVar VariationId is 203832.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.616C>T	p.Arg206Trp	missense	Exon 4 of 4	NP_056321.2	Q9Y4U1
	MMACHC	NM_001330540.2		c.445C>T	p.Arg149Trp	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.616C>T	p.Arg206Trp	missense	Exon 4 of 4	ENSP00000383840.4	Q9Y4U1
MMACHC	ENST00000616135.1	TSL:2	c.445C>T	p.Arg149Trp	missense	Exon 4 of 5	ENSP00000478859.1	A0A0C4DGU2
MMACHC	ENST00000933807.1		c.421C>T	p.Arg141Trp	missense	Exon 3 of 3	ENSP00000603866.1

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152168

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:

0.00

Gnomad FIN

AF:

0.0000941

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000401

AC:

AN:

249530

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.0000556

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000684

AC:

AN:

1461882

Hom.:

Cov.:

AF XY:

0.00000550

AC XY:

AN XY:

727244

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33480

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.0000504

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.000173

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00000450

AC:

AN:

1112006

Other (OTH)

AF:

0.0000166

AC:

AN:

60396

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.490

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:

152168

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74350

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41424

American (AMR)

AF:

0.00

AC:

AN:

15272

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.0000941

AC:

AN:

10626

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68028

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.575

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome 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

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ClinVar

ClinVar submissions

Significance:Pathogenic

Revision:criteria provided, multiple submitters, no conflicts

View on ClinVar

Pathogenic

VUS

Benign

Condition

Cobalamin C disease (6)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.82

BayesDel_addAF

Pathogenic

0.40

BayesDel_noAF

Pathogenic

0.50

CADD

Uncertain

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.93

Eigen

Uncertain

0.40

Eigen_PC

Uncertain

0.28

FATHMM_MKL

Uncertain

0.91

LIST_S2

Uncertain

0.92

M_CAP

Pathogenic

0.68

MetaRNN

Pathogenic

0.99

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

3.4

PhyloP100

-0.029

PrimateAI

Uncertain

0.59

PROVEAN

Pathogenic

-7.8

REVEL

Pathogenic

0.89

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0

Polyphen

1.0

Vest4

0.94

MutPred

0.96

Loss of disorder (P = 0.0516)

MVP

0.97

MPC

0.081

ClinPred

1.0

GERP RS

1.4

Varity_R

0.97

gMVP

0.98

Mutation Taster

=1/99

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

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over