rs920825350

Variant names:

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM1PM2PP3_ModeratePP5

The NM_172250.3(MMAA):c.664A>G(p.Arg222Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,806 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 Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. R222R) has been classified as Likely benign.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 0.0000034 ( 0 hom. )

Consequence

MMAA
NM_172250.3 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1U:3

Conservation

PhyloP100: 2.44

Publications

1 publications found

Variant links:

Genes affected

MMAA (HGNC:18871): (metabolism of cobalamin associated A) The protein encoded by this gene is involved in the translocation of cobalamin into the mitochondrion, where it is used in the final steps of adenosylcobalamin synthesis. Adenosylcobalamin is a coenzyme required for the activity of methylmalonyl-CoA mutase. Defects in this gene are a cause of methylmalonic aciduria. [provided by RefSeq, Jul 2008]

MMAA Gene-Disease associations (from GenCC):

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

MMAA links:

ENSG00000248356 (HGNC:):

ENSG00000248356 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

PM1

In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 2 uncertain in NM_172250.3

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.894

PP5

Variant 4-145646087-A-G is Pathogenic according to our data. Variant chr4-145646087-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 522648.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MMAA	NM_172250.3 link	c.664A>G	p.Arg222Gly	missense_variant	Exon 4 of 7	ENST00000649156.2	NP_758454.1	Q8IVH4
MMAA	NM_001375644.1 link	c.664A>G	p.Arg222Gly	missense_variant	Exon 4 of 7		NP_001362573.1
MMAA	XM_011531684.4 link	c.664A>G	p.Arg222Gly	missense_variant	Exon 4 of 7		XP_011529986.1	Q8IVH4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MMAA	ENST00000649156.2 link	c.664A>G	p.Arg222Gly	missense_variant	Exon 4 of 7		NM_172250.3	ENSP00000497008.1		Q8IVH4

Frequencies

GnomAD3 genomes

Cov.:

GnomAD2 exomes

AF:

0.00000398

AC:

AN:

251422

AF XY:

0.00000736

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

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:

0.00000342

AC:

AN:

1461806

Hom.:

Cov.:

AF XY:

0.00000413

AC XY:

AN XY:

727200

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33480

American (AMR)

AF:

0.0000224

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39682

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53420

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111952

Other (OTH)

AF:

0.0000662

AC:

AN:

60390

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.515

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

Cov.:

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000756

Asia WGS

AF:

0.000289

AC:

AN:

3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:3

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Methylmalonic aciduria, cblA type

Pathogenic:1Uncertain:2

Aug 09, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 222 of the MMAA protein (p.Arg222Gly). This variant is present in population databases (no rsID available, gnomAD 0.003%). This variant has not been reported in the literature in individuals affected with MMAA-related conditions. ClinVar contains an entry for this variant (Variation ID: 522648). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt MMAA protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Dec 03, 2017

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Mar 11, 2025

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Inborn genetic diseases

Uncertain:1

May 24, 2023

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.664A>G (p.R222G) alteration is located in exon 4 (coding exon 3) of the MMAA gene. This alteration results from a A to G substitution at nucleotide position 664, causing the arginine (R) at amino acid position 222 to be replaced by a glycine (G). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Uncertain

0.54

BayesDel_addAF

Pathogenic

0.37

BayesDel_noAF

Pathogenic

0.38

CADD

Uncertain

(source)

DANN

Pathogenic

1.0

DEOGEN2

Pathogenic

0.81

D;.;D;D;D;D

Eigen

Uncertain

0.68

Eigen_PC

Uncertain

0.63

FATHMM_MKL

Uncertain

0.80

LIST_S2

Pathogenic

1.0

.;D;.;.;D;D

M_CAP

Pathogenic

0.45

MetaRNN

Pathogenic

0.89

D;D;D;D;D;D

MetaSVM

Pathogenic

0.85

MutationAssessor

Pathogenic

2.9

M;.;M;M;M;.

PhyloP100

2.4

PrimateAI

Uncertain

0.76

PROVEAN

Pathogenic

-6.0

.;.;D;.;.;.

REVEL

Pathogenic

0.86

Sift

Uncertain

0.0030

.;.;D;.;.;.

Sift4G

Uncertain

0.0030

.;.;D;.;.;D

Polyphen

1.0

D;.;D;D;D;.

Vest4

0.91, 0.91

MutPred

0.67

Gain of catalytic residue at G219 (P = 0.0615);Gain of catalytic residue at G219 (P = 0.0615);Gain of catalytic residue at G219 (P = 0.0615);Gain of catalytic residue at G219 (P = 0.0615);Gain of catalytic residue at G219 (P = 0.0615);Gain of catalytic residue at G219 (P = 0.0615);

MVP

0.98

MPC

0.62

ClinPred

0.99

GERP RS

5.4

Varity_R

0.90

gMVP

0.93

Mutation Taster

=27/73

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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over