rs35068278

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 3P and 4B. PM1PP3BS2

The NM_022132.5(MCCC2):c.1433C>G(p.Ala478Gly) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00145 in 1,614,060 control chromosomes in the GnomAD database, including 5 homozygotes. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A478P) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.00079 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0015 ( 5 hom. )

Consequence

MCCC2
NM_022132.5 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2U:8O:1

Conservation

PhyloP100: 7.88

Publications

9 publications found

Variant links:

Genes affected

MCCC2 (HGNC:6937): (methylcrotonyl-CoA carboxylase subunit 2) This gene encodes the small subunit of 3-methylcrotonyl-CoA carboxylase. This enzyme functions as a heterodimer and catalyzes the carboxylation of 3-methylcrotonyl-CoA to form 3-methylglutaconyl-CoA. Mutations in this gene are associated with 3-Methylcrotonylglycinuria, an autosomal recessive disorder of leucine catabolism. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, May 2018]

MCCC2 Gene-Disease associations (from GenCC):

3-methylcrotonyl-CoA carboxylase 2 deficiency
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
3-methylcrotonyl-CoA carboxylase deficiency
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet

MCCC2 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

PM1

In a hotspot region, there are 5 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 5 uncertain in NM_022132.5

PP3

MetaRNN computational evidence supports a deleterious effect, 0.809

BS2

High Homozygotes in GnomAdExome4 at 5 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MCCC2	NM_022132.5 link	c.1433C>G	p.Ala478Gly	missense_variant	Exon 15 of 17	ENST00000340941.11	NP_071415.1	Q9HCC0-1A0A140VK29
MCCC2	NM_001363147.1 link	c.1319C>G	p.Ala440Gly	missense_variant	Exon 14 of 16		NP_001350076.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MCCC2	ENST00000340941.11 link	c.1433C>G	p.Ala478Gly	missense_variant	Exon 15 of 17	1	NM_022132.5	ENSP00000343657.6		Q9HCC0-1

Frequencies

GnomAD3 genomes

AF:

0.000795

AC:

121

AN:

152210

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.0000942

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00141

Gnomad OTH

AF:

0.000956

GnomAD2 exomes

AF:

0.000469

AC:

118

AN:

251382

AF XY:

0.000486

show subpopulations

Gnomad AFR exome

AF:

0.000246

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.000139

Gnomad NFE exome

AF:

0.000933

Gnomad OTH exome

AF:

0.000815

GnomAD4 exome

AF:

0.00151

AC:

2213

AN:

1461850

Hom.:

Cov.:

AF XY:

0.00145

AC XY:

1053

AN XY:

727224

show subpopulations

African (AFR)

AF:

0.000179

AC:

AN:

33480

American (AMR)

AF:

0.0000224

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.000206

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.00181

AC:

2017

AN:

1111976

Other (OTH)

AF:

0.00295

AC:

178

AN:

60394

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.457

Heterozygous variant carriers

107

214

322

429

536

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

168

252

336

420

<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:

0.000795

AC:

121

AN:

152210

Hom.:

Cov.:

AF XY:

0.000740

AC XY:

AN XY:

74360

show subpopulations

African (AFR)

AF:

0.000483

AC:

AN:

41446

American (AMR)

AF:

0.000131

AC:

AN:

15280

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.0000942

AC:

AN:

10620

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00141

AC:

AN:

68048

Other (OTH)

AF:

0.000956

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.507

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:

0.00116

Hom.:

Bravo

AF:

0.000801

TwinsUK

AF:

0.00135

AC:

ALSPAC

AF:

0.00130

AC:

ESP6500AA

AF:

0.000454

AC:

ESP6500EA

AF:

0.00221

AC:

ExAC

AF:

0.000428

AC:

EpiCase

AF:

0.00174

EpiControl

AF:

0.000830

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2Uncertain:8Other:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

3-methylcrotonyl-CoA carboxylase 2 deficiency

Pathogenic:1Uncertain:3

Jan 26, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with glycine, which is neutral and non-polar, at codon 478 of the MCCC2 protein (p.Ala478Gly). This variant is present in population databases (rs35068278, gnomAD 0.1%), and has an allele count higher than expected for a pathogenic variant. This missense change has been observed in individual(s) with 3 Methylcrotonyl-CoA carboxylase deficiency (internal data). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 96030). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed for this missense variant. However, the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on MCCC2 protein function. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Oct 31, 2018

Fulgent Genetics, Fulgent Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Jan 10, 2023

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:research

- -

not provided

Pathogenic:1Uncertain:2

Jun 15, 2024

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Reported as heterozygous in an individual with seizures and developmental delay who also had a de novo variant in PP2D1 and a variant in SCN9A (PMID: 31847883); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 31847883) -

Feb 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

MCCC2: PM5 -

May 15, 2018

Eurofins Ntd Llc (ga)

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Methylcrotonyl-CoA carboxylase deficiency

Uncertain:1Other:1

Sep 16, 2020

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

GenomeConnect, ClinGen

Significance:not provided

Review Status:no classification provided

Collection Method:phenotyping only

Variant classified as Uncertain significance and reported on 03-12-2021 by GeneDx. GenomeConnect assertions are reported exactly as they appear on the patient-provided report from the testing laboratory. GenomeConnect staff make no attempt to reinterpret the clinical significance of the variant. -

not specified

Uncertain:1

May 15, 2025

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

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: MCCC2 c.1433C>G (p.Ala478Gly) results in a non-conservative amino acid change located in the Acetyl-coenzyme A carboxyltransferase, C-terminal domain (IPR011763) of the encoded protein sequence. Algorithms developed to predict the effect of missense changes on protein structure and function all suggest that this variant is likely to be disruptive. The variant allele was found at a frequency of 0.00047 in 251382 control chromosomes. This frequency is not significantly higher than estimated for a pathogenic variant in MCCC2 causing Methylcrotonyl-CoA Carboxylase Deficiency (0.00047 vs 0.0042), allowing no conclusion about variant significance. c.1433C>G has been reported in the literature in at least one individual affected with Infantile spasms and uncontrolled seizures (e.g. Salfati_2019). These report(s) do not provide unequivocal conclusions about association of the variant with Methylcrotonyl-CoA Carboxylase Deficiency. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 31847883, 38256266). ClinVar contains an entry for this variant (Variation ID: 96030). Based on the evidence outlined above, the variant was classified as uncertain significance. -

Inborn genetic diseases

Uncertain:1

May 02, 2022

Ambry Genetics

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The c.1433C>G (p.A478G) alteration is located in exon 15 (coding exon 15) of the MCCC2 gene. This alteration results from a C to G substitution at nucleotide position 1433, causing the alanine (A) at amino acid position 478 to be replaced by a glycine (G). Based on data from the Genome Aggregation Database (gnomAD) database, the MCCC2 c.1433C>G alteration was observed in 0.05% (145/282,790) of total alleles studied, with a frequency of 0.1% (128/129,106) in the European (non-Finnish) subpopulation. The p.A478G alteration is predicted to be deleterious by in silico analysis. 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

Pathogenic

0.59

BayesDel_addAF

Uncertain

0.11

BayesDel_noAF

Pathogenic

0.35

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.91

D;.

Eigen

Pathogenic

1.1

Eigen_PC

Pathogenic

1.0

FATHMM_MKL

Pathogenic

1.0

LIST_S2

Pathogenic

0.99

D;D

M_CAP

Pathogenic

0.63

MetaRNN

Pathogenic

0.81

D;D

MetaSVM

Pathogenic

1.1

MutationAssessor

Pathogenic

4.1

H;.

PhyloP100

7.9

PrimateAI

Uncertain

0.63

PROVEAN

Uncertain

-3.7

D;D

REVEL

Pathogenic

0.86

Sift

Pathogenic

0.0

D;D

Sift4G

Uncertain

0.029

D;D

Polyphen

1.0

D;.

Vest4

0.76

MVP

0.99

MPC

0.49

ClinPred

0.79

GERP RS

5.8

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.91

gMVP

0.92

Mutation Taster

=26/74

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

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over