rs766753795

Variant names:

• chr5-71626703-A-G
• rs766753795
• NM_022132.5:c.688A>G

Variant summary

Our verdict is Pathogenic. Variant got 11 ACMG points: 11P and 0B. PM2 PP3 PP5_Very_Strong

The NM_022132.5(MCCC2):​c.688A>G​(p.Asn230Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000103 in 1,461,884 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 (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.000010 (0 hom.)
• Consequence: MCCC2 NM_022132.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 9.07

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]

ACMG classification

Verdict is Pathogenic. Variant got 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.791
• PP5: Variant 5-71626703-A-G is Pathogenic according to our data. Variant chr5-71626703-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 577397.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MCCC2	NM_022132.5	c.688A>G	p.Asn230Asp	missense_variant	Exon 7 of 17	ENST00000340941.11	NP_071415.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MCCC2	ENST00000340941.11	c.688A>G	p.Asn230Asp	missense_variant	Exon 7 of 17	1	NM_022132.5	ENSP00000343657.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.0000103 AC: 15 AN: 1461884 Hom.: 0 Cov.: 31 AF XY: 0.00000825 AC XY: 6 AN XY: 727248

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000126

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Bravo AF: 0.0000113

TwinsUK AF: 0.000270 AC: 1

ALSPAC AF: 0.00 AC: 0

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

3-methylcrotonyl-CoA carboxylase 2 deficiency Pathogenic:2

Feb 23, 2024

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 07, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces asparagine, which is neutral and polar, with aspartic acid, which is acidic and polar, at codon 230 of the MCCC2 protein (p.Asn230Asp). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with 3-methylcrotonyl-CoA carboxylase deficiency (PMID: 27601257). ClinVar contains an entry for this variant (Variation ID: 577397). 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. For these reasons, this variant has been classified as Pathogenic. -

Methylcrotonyl-CoA carboxylase deficiency Pathogenic:1

Jan 19, 2022

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: MCCC2 c.688A>G (p.Asn230Asp) results in a conservative amino acid change located in the Acetyl-coenzyme A carboxyltransferase, N-terminal domain (IPR011762) of the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251474 control chromosomes. c.688A>G has been reported in the literature as homozygous and compound heterozygous genotypes in multiple asymptomatic newborns and at-least one asymptomatic mother affected with Methylcrotonyl-CoA Carboxylase Deficiency, supported by elevated 3- hydroxyisovalerylcarnitine (C5-OH) levels above the established screening cutoff of >/= 1 micromol/L (example, Fonseca_2016). At-least two of these individuals also had supportive biochemical phenotype of elevated 3-hydroxyisovaleric acid (3-HIVA) and 3-methylcrotonylglycine (3-MCG) levels. Patients with 3-MCC deficiency experience normal growth and development until the emergence of an acute episode of metabolic decompensation, occurring typically between 6 months and 3 to 5 years of age (example, Sweetman, 2001). This episode is usually triggered by an infection or the introduction of high protein foods in the diet. Therefore, these newborn screening data indicate that the variant is very likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 and classified the variant as pathogenic citing overlapping evidence utilized in the context of this evaluation. Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.52
BayesDel_addAF	Pathogenic	0.20	D
BayesDel_noAF	Uncertain	0.050
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.76	D;.;.
Eigen	Uncertain	0.32
Eigen_PC	Uncertain	0.44
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;D;D
M_CAP	Uncertain	0.29	D
MetaRNN	Pathogenic	0.79	D;D;D
MetaSVM	Pathogenic	0.89	D
MutationAssessor	Uncertain	2.3	M;.;.
PrimateAI	Uncertain	0.76	T
PROVEAN	Benign	-1.5	N;N;N
REVEL	Pathogenic	0.66
Sift	Uncertain	0.0010	D;D;D
Sift4G	Uncertain	0.0060	D;D;D
Polyphen		0.26	B;P;.
Vest4		0.49
MutPred		0.57		Loss of catalytic residue at N230 (P = 0.075);Loss of catalytic residue at N230 (P = 0.075);.;
MVP		0.82
MPC		0.19
ClinPred		0.95	D
GERP RS		5.4
Varity_R		0.88
gMVP		0.62

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

LitVar

Other links and lift over

dbSNP: rs766753795; hg19: chr5-70922530;