rs1304714042

Positions:

• chr3-136262016-G-A

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_000532.5(PCCB):​c.494G>A​(p.Arg165Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000355 in 1,408,544 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R165W) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000035 (0 hom.)
• Consequence: PCCB NM_000532.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 9.50

Genes affected

PCCB (HGNC:8654): (propionyl-CoA carboxylase subunit beta) The protein encoded by this gene is a subunit of the propionyl-CoA carboxylase (PCC) enzyme, which is involved in the catabolism of propionyl-CoA. PCC is a mitochondrial enzyme that probably acts as a dodecamer of six alpha subunits and six beta subunits. This gene encodes the beta subunit of PCC. Defects in this gene are a cause of propionic acidemia type II (PA-2). Multiple transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, May 2010]

PCCB (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr3-136262015-C-T is described in Lovd as [Likely_pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.971
• PP5: Variant 3-136262016-G-A is Pathogenic according to our data. Variant chr3-136262016-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 551146.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr3-136262016-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PCCB	NM_000532.5	c.494G>A	p.Arg165Gln	missense_variant	5/15	ENST00000251654.9	NP_000523.2
PCCB	NM_001178014.2	c.554G>A	p.Arg185Gln	missense_variant	6/16		NP_001171485.1
PCCB	XM_011512873.2	c.494G>A	p.Arg165Gln	missense_variant	5/11		XP_011511175.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PCCB	ENST00000251654.9	c.494G>A	p.Arg165Gln	missense_variant	5/15	1	NM_000532.5	ENSP00000251654.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000589 AC: 1 AN: 169706 Hom.: 0 AF XY: 0.0000112 AC XY: 1 AN XY: 89308

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 SAS exome AF: 0.0000425

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000355 AC: 5 AN: 1408544 Hom.: 0 Cov.: 30 AF XY: 0.00000288 AC XY: 2 AN XY: 695426

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: 0.0000125

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000277

Gnomad4 OTH exome AF: 0.0000171

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Propionic acidemia Pathogenic:5

Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Apr 13, 2022	- -
Pathogenic, criteria provided, single submitter	clinical testing	Lifecell International Pvt. Ltd	-	A Homozygote Missense variant c.494G>A in Exon 5 of the PCCB gene that results in the amino acid substitution p.Arg165Gln was identified. The observed variant has a maximum allele frequency of 0.00001/0.00 % in gnomAD exomes and genomes, respectively. The severity of the impact of this variant on the protein is high, based on the effect of the protein and REVEL score . Rare Exome Variant Ensemble Learner (REVEL) is an ensembl method for predicting the pathogenicity of missense variants based on a combination of scores from 13 individual tools: MutPred, FATHMM v2.3, VEST 3.0, PolyPhen-2, SIFT, PROVEAN, MutationAssessor, MutationTaster, LRT, GERP++, SiPhy, phyloP, and phastCons. The REVEL score for an individual missense variant can range from 0 to 1, with higher scores reflecting greater likelihood that the variant is disease-causing. ClinVar has also classified this variant as Pathogenic/LikelyPathogenic (ClinVar ID: 551146). This variant has previously been reported for Propionic acidemia by Stanescu S et al., 2021. Furthermore, functional studies demonstrate that this variant has a damaging effect on the gene or gene product (Pérez-Cerdá C et al., 2003). Based on the above evidence this variant has been classified as Pathogenic according to the ACMG guidelines. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Mar 17, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	Women's Health and Genetics/Laboratory Corporation of America, LabCorp	Aug 13, 2024	Variant summary: PCCB c.494G>A (p.Arg165Gln) 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 5.9e-06 in 169706 control chromosomes (gnomAD). c.494G>A has been reported in the literature in individuals affected with Propionic Acidemia (e.g. Muro_2001, Perez-Cerda_2003). These data indicate that the variant is likely to be associated with disease. A different variant affecting the same codon has been classified as pathogenic by our lab (c.493C>T, p.Arg165Trp), supporting the critical relevance of codon 165 to PCCB protein function. At least one publication reports experimental evidence evaluating an impact on enzymatic function, finding that the variant results in <1% of wild type PCC activity (Perez-Cerda_2003). The following publications have been ascertained in the context of this evaluation (PMID: 11749052, 12559849). ClinVar contains an entry for this variant (Variation ID: 551146). Based on the evidence outlined above, the variant was classified as pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 15, 2023	This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 165 of the PCCB protein (p.Arg165Gln). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individuals with propionic acidemia (PMID: 11749052, 12757933). ClinVar contains an entry for this variant (Variation ID: 551146). 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 PCCB protein function with a positive predictive value of 95%. Experimental studies have shown that this missense change affects PCCB function (PMID: 12757933). This variant disrupts the p.Arg165 amino acid residue in PCCB. Other variant(s) that disrupt this residue have been observed in individuals with PCCB-related conditions (PMID: 8295402, 11749052, 12757933, 15949719, 20549364), which suggests that this may be a clinically significant amino acid residue. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	34
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.95	D;.;D;D;D;.;.;.;D;D;.
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Pathogenic	1.0	D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.49	D
MetaRNN	Pathogenic	0.97	D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.99	D
MutationAssessor	Pathogenic	4.8	H;.;.;.;.;.;.;.;.;.;.
PrimateAI	Uncertain	0.75	T
PROVEAN	Uncertain	-3.7	D;D;D;D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;D;D;D;D;D;D;D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D;D;D;D;D;D;D;D
Polyphen		1.0	D;.;.;.;.;.;D;.;.;.;.
Vest4		0.94
MutPred		0.86		Loss of helix (P = 0.0558);.;.;.;Loss of helix (P = 0.0558);.;Loss of helix (P = 0.0558);.;Loss of helix (P = 0.0558);.;.;
MVP		0.98
MPC		0.54
ClinPred		1.0	D
GERP RS		5.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.93
gMVP		0.86

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: rs1304714042; hg19: chr3-135980858;