Genetic Variant NM_020166.5:c.2051A>C (chr3-183015565-T-G) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2PP3_Moderate

The NM_020166.5(MCCC1):c.2051A>C(p.His684Pro) variant causes a missense, splice region change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,832 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 predict no significant impact on normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. H684R) has been classified as Uncertain significance.

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

MCCC1
NM_020166.5 missense, splice_region

Scores

Splicing: ADA: 0.004810

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 3.47

Publications

0 publications found

Variant links:

Genes affected

MCCC1 (HGNC:6936): (methylcrotonyl-CoA carboxylase subunit 1) This gene encodes the large 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. [provided by RefSeq, Jul 2008]

MCCC1 Gene-Disease associations (from GenCC):

3-methylcrotonyl-CoA carboxylase 1 deficiency
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: G2P, Ambry Genetics, Labcorp Genetics (formerly Invitae)
3-methylcrotonyl-CoA carboxylase deficiency
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen

MCCC1 links:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

PP3

MetaRNN computational evidence supports a deleterious effect, 0.868

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MCCC1	NM_020166.5 link	c.2051A>C	p.His684Pro	missense_variant, splice_region_variant	Exon 19 of 19	ENST00000265594.9	NP_064551.3	Q96RQ3A0A0S2Z693

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MCCC1	ENST00000265594.9 link	c.2051A>C	p.His684Pro	missense_variant, splice_region_variant	Exon 19 of 19	1	NM_020166.5	ENSP00000265594.4		Q96RQ3

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461832

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727220

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33478

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26132

East Asian (EAS)

AF:

0.00

AC:

AN:

39696

South Asian (SAS)

AF:

0.0000116

AC:

AN:

86256

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53412

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111972

Other (OTH)

AF:

0.00

AC:

AN:

60394

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.72

BayesDel_addAF

Uncertain

0.15

BayesDel_noAF

Uncertain

-0.020

CADD

Uncertain

(source)

DANN

Uncertain

0.98

DEOGEN2

Uncertain

0.78

D;T;T

Eigen

Uncertain

0.57

Eigen_PC

Uncertain

0.46

FATHMM_MKL

Uncertain

0.97

LIST_S2

Uncertain

0.95

D;D;D

M_CAP

Uncertain

0.13

MetaRNN

Pathogenic

0.87

D;D;D

MetaSVM

Uncertain

-0.20

MutationAssessor

Pathogenic

3.6

H;.;.

PhyloP100

3.5

PrimateAI

Uncertain

0.59

PROVEAN

Pathogenic

-7.4

D;D;.

REVEL

Uncertain

0.42

Sift

Uncertain

0.0030

D;D;.

Sift4G

Uncertain

0.0030

D;D;D

Polyphen

0.98

D;D;.

Vest4

0.70

MutPred

0.73

Gain of disorder (P = 0.0492);.;.;

MVP

0.79

MPC

0.71

ClinPred

0.99

GERP RS

3.3

Varity_R

0.92

gMVP

0.93

Mutation Taster

=43/57

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Benign

0.0048

dbscSNV1_RF

Benign

0.25

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

ClinVar

Computational scores

Splicing

Publications

Other links and lift over