rs773774134

Variant names:

• chr5-71604412-C-T
• rs773774134
• NM_022132.5:c.568C>T

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM1 PM2 PM5 PP3_Strong PP5

The NM_022132.5(MCCC2):​c.568C>T​(p.His190Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000105 in 1,613,966 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. H190R) has been classified as Pathogenic.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000089 (0 hom.)
• Consequence: MCCC2 NM_022132.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:6 U:1
• Conservation: PhyloP100: 7.62

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

Our verdict: Pathogenic. The variant received 11 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, 5 uncertain in NM_022132.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr5-71604413-A-G is described in ClinVar as [Pathogenic]. Clinvar id is 1926.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.986
• PP5: Variant 5-71604412-C-T is Pathogenic according to our data. Variant chr5-71604412-C-T is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 198252.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=2, Pathogenic=3}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
MCCC2	NM_022132.5	c.568C>T	p.His190Tyr	missense_variant	Exon 6 of 17	ENST00000340941.11	NP_071415.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
MCCC2	ENST00000340941.11	c.568C>T	p.His190Tyr	missense_variant	Exon 6 of 17	1	NM_022132.5	ENSP00000343657.6

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152090 Hom.: 0 Cov.: 32

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: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000588

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000159 AC: 4 AN: 251464 AF XY: 0.0000147

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000889 AC: 13 AN: 1461876 Hom.: 0 Cov.: 31 AF XY: 0.0000124 AC XY: 9 AN XY: 727236

Gnomad4 AFR exome AF: 0.00 AC: 0 AN: 33480

Gnomad4 AMR exome AF: 0.00 AC: 0 AN: 44724

Gnomad4 ASJ exome AF: 0.00 AC: 0 AN: 26136

Gnomad4 EAS exome AF: 0.00 AC: 0 AN: 39698

Gnomad4 SAS exome AF: 0.0000812 AC: 7 AN: 86258

Gnomad4 FIN exome AF: 0.00 AC: 0 AN: 53416

Gnomad4 NFE exome AF: 0.00000360 AC: 4 AN: 1112000

Gnomad4 Remaining exome AF: 0.0000331 AC: 2 AN: 60396

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152090 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74306

Gnomad4 AFR AF: 0.00 AC: 0 AN: 0

Gnomad4 AMR AF: 0.00 AC: 0 AN: 0

Gnomad4 ASJ AF: 0.00 AC: 0 AN: 0

Gnomad4 EAS AF: 0.00 AC: 0 AN: 0

Gnomad4 SAS AF: 0.00 AC: 0 AN: 0

Gnomad4 FIN AF: 0.00 AC: 0 AN: 0

Gnomad4 NFE AF: 0.0000588 AC: 0.0000587993 AN: 0.0000587993

Gnomad4 OTH AF: 0.00 AC: 0 AN: 0

Alfa AF: 0.0000127 Hom.: 0

Bravo AF: 0.0000264

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:6 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

3-methylcrotonyl-CoA carboxylase 2 deficiency Pathogenic:2 Uncertain:1

Nov 29, 2023

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Oct 15, 2018

SIB Swiss Institute of Bioinformatics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

This variant is interpreted as Likely Pathogenic, for MCC2 deficiency, autosomal recessive. The following ACMG Tag(s) were applied: PM2 => Absent from controls (or at extremely low frequency if recessive) in Exome Sequencing Project, 1000 Genomes Project, or Exome Aggregation Consortium. PP3 => Multiple lines of computational evidence support a deleterious effect on the gene or gene product. PS3 => Well-established functional studies show a deleterious effect (https://www.ncbi.nlm.nih.gov/pubmed/16010683). -

Sep 01, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces histidine with tyrosine at codon 190 of the MCCC2 protein (p.His190Tyr). The histidine residue is highly conserved and there is a moderate physicochemical difference between histidine and tyrosine. This variant is present in population databases (rs773774134, ExAC 0.001%). This missense change has been observed in individual(s) with 3-methylcrotonyl-CoA carboxylase deficiency (PMID: 16010683). ClinVar contains an entry for this variant (Variation ID: 198252). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. Experimental studies have shown that this missense change affects MCCC2 function (PMID: 16010683). This variant disrupts the p.His190 amino acid residue in MCCC2. Other variant(s) that disrupt this residue have been observed in individuals with MCCC2-related conditions (PMID: 16010683, 17968484), which suggests that this may be a clinically significant amino acid residue. 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. -

not provided Pathogenic:2

May 04, 2015

Eurofins Ntd Llc (ga)

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Sep 20, 2018

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The H190Y variant in the MCCC2 gene has been reported previously in association with 3-methylcrotonyl-CoA carboxylase deficiency, in an affected individual who was homozygous for the H190Y variant (Dantas et al., 2005). This variant is not observed at a significant frequency in large population cohorts (Lek et al., 2016). The H190Y variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. In-silico analyses, including protein predictors and evolutionary conservation, support a deleterious effect, and expression studies found that H190Y is associated with severely decreased 3-methylcrotonyl-CoA carboxylase activity (Dantas et al., 2005). Missense variants in the same codon (H190R) and nearby residues (R193C and R193H) have been reported in the Human Gene Mutation Database in association with 3-methylcrotonyl-CoA carboxylase deficiency (Stenson et al., 2014), supporting the functional importance of this region of the protein. We interpret H190Y as a pathogenic variant. -

Methylcrotonyl-CoA carboxylase deficiency Pathogenic:1

Sep 10, 2022

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: MCCC2 c.568C>T (p.His190Tyr) results in a conservative amino acid change located in the Acetyl-coenzyme A carboxyltransferase, N-terminal domain (IPR011762) of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 1.6e-05 in 251464 control chromosomes. c.568C>T has been reported in the literature as a homozygous genotype in at-least one individual affected with a mild phenotype of Methylcrotonyl-CoA Carboxylase Deficiency (example, Dantas_2005). These data indicate that the variant may be associated with disease. At least one publication reports experimental evidence evaluating an impact on protein function in-vitro (example, Dantas_2005). The most pronounced variant effect results in absence of normal 3-methylcrotonyl-CoA carboxylase (MCC) activity. Four clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 (VUS, n=1; P/LP, n=3). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

MCCC2-related disorder Pathogenic:1

Jul 15, 2024

PreventionGenetics, part of Exact Sciences

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

The MCCC2 c.568C>T variant is predicted to result in the amino acid substitution p.His190Tyr. This variant was reported in the homozygous state in one mildly affected individual with 3-methylcrotonyl-CoA carboxylase deficiency (Dantas et al 2005. PubMed ID: 16010683). In an in vitro expression study, the p.His190Tyr substitution was reported to abolish enzyme activity (Dantas et al 2005. PubMed ID: 16010683). An alternative substitution of the same amino acid (p.His190Arg) was reported along with a second likely pathogenic MCCC2 variant in an individual with 3-methylcrotonyl-CoA carboxylase deficiency (Uematsu et al. 2007. PubMed ID: 17968484). This variant is reported in 0.0033% of alleles in individuals of South Asian descent in gnomAD. This variant is interpreted as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.45
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.56
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.78	D;D;.
Eigen	Pathogenic	0.96
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	0.99	D;D;D
M_CAP	Pathogenic	0.33	D
MetaRNN	Pathogenic	0.99	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	2.9	.;M;.
PrimateAI	Uncertain	0.55	T
PROVEAN	Pathogenic	-5.7	.;D;D
REVEL	Pathogenic	0.97
Sift	Pathogenic	0.0	.;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0, 0.92	.;D;P
Vest4		0.96
MutPred		0.91		Loss of catalytic residue at R188 (P = 0.0595);Loss of catalytic residue at R188 (P = 0.0595);Loss of catalytic residue at R188 (P = 0.0595);
MVP		0.99
MPC		0.56
ClinPred		0.97	D
GERP RS		5.6
Varity_R		0.94
gMVP		0.92
Mutation Taster		=4/96	disease causing (ClinVar)

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: rs773774134; hg19: chr5-70900239;