Genetic Variant PCCA:p.Gly477Val (chr13-100330561-G-T) – ACMG Classification: Likely_pathogenic (6 pts)

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1PM2PP3PP5

The NM_000282.4(PCCA):c.1430G>T(p.Gly477Val) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000206 in 1,551,784 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. 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. G477S) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000021 ( 0 hom. )

Consequence

PCCA
NM_000282.4 missense, splice_region

Scores

Splicing: ADA: 0.9995

Clinical Significance

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

Conservation

PhyloP100: 7.74

Publications

4 publications found

Variant links:

Genes affected

PCCA (HGNC:8653): (propionyl-CoA carboxylase subunit alpha) The protein encoded by this gene is the alpha subunit of the heterodimeric mitochondrial enzyme Propionyl-CoA carboxylase. PCCA encodes the biotin-binding region of this enzyme. Mutations in either PCCA or PCCB (encoding the beta subunit) lead to an enzyme deficiency resulting in propionic acidemia. Multiple transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, May 2010]

PCCA Gene-Disease associations (from GenCC):

propionic acidemia
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, ClinGen, Orphanet

PCCA links:

LOC105370335 (HGNC:):

LOC105370335 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

PM1

In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 7 uncertain in NM_000282.4

PM2

Very rare variant in population databases, with high coverage;

PP3

Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. Scorers claiming Uncertain: max_spliceai. No scorers claiming Benign.

PP5

Variant 13-100330561-G-T is Pathogenic according to our data. Variant chr13-100330561-G-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 550273.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000282.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
PCCA	NM_000282.4	MANE Select	c.1430G>T	p.Gly477Val	missense splice_region	Exon 17 of 24	NP_000273.2
PCCA	NM_001352605.2		c.1430G>T	p.Gly477Val	missense splice_region	Exon 17 of 23	NP_001339534.1
PCCA	NM_001127692.3		c.1352G>T	p.Gly451Val	missense splice_region	Exon 16 of 23	NP_001121164.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein
PCCA	ENST00000376285.6	TSL:1 MANE Select	c.1430G>T	p.Gly477Val	missense splice_region	Exon 17 of 24	ENSP00000365462.1
PCCA	ENST00000376286.8	TSL:2	c.1352G>T	p.Gly451Val	missense splice_region	Exon 16 of 23	ENSP00000365463.4
PCCA	ENST00000376279.7	TSL:2	c.1430G>T	p.Gly477Val	missense splice_region	Exon 17 of 23	ENSP00000365456.3

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

151982

Hom.:

Cov.:

show subpopulations

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:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.0000214

AC:

AN:

1399802

Hom.:

Cov.:

AF XY:

0.0000243

AC XY:

AN XY:

700134

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

32268

American (AMR)

AF:

0.00

AC:

AN:

44662

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25728

East Asian (EAS)

AF:

0.00

AC:

AN:

39268

South Asian (SAS)

AF:

0.00

AC:

AN:

85040

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52304

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5646

European-Non Finnish (NFE)

AF:

0.0000265

AC:

AN:

1056648

Other (OTH)

AF:

0.0000343

AC:

AN:

58238

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.512

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome 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

GnomAD4 genome

AF:

0.0000132

AC:

AN:

151982

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74224

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41368

American (AMR)

AF:

0.00

AC:

AN:

15246

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5196

South Asian (SAS)

AF:

0.00

AC:

AN:

4822

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10566

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

67998

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000283

Hom.:

Bravo

AF:

0.0000151

EpiCase

AF:

0.000109

EpiControl

AF:

0.00

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1Uncertain:1

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Propionic acidemia

Pathogenic:1Uncertain:1

Nov 08, 2021

Myriad Genetics, Inc.

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

NM_000282.3(PCCA):c.1430G>T(G477V) is a missense variant classified as a variant of uncertain significance in the context of PCCA-related propionic acidemia. G477V has been observed in cases with relevant disease (PMID: 17051315). Functional assessments of this variant are not available in the literature. G477V has not been observed in population frequency databases. In summary, there is insufficient evidence to classify NM_000282.3(PCCA):c.1430G>T(G477V) as pathogenic or benign. Please note: this variant was assessed in the context of healthy population screening.

Nov 06, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 477 of the PCCA protein (p.Gly477Val). RNA analysis indicates that this missense change induces altered splicing and likely results in a shortened protein product. This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of propionic acidemia (PMID: 17051315; 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: 550273). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Studies have shown that this missense change results in skipping of exon 17, but is expected to preserve the integrity of the reading-frame (PMID: 17051315). For these reasons, this variant has been classified as Pathogenic.

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Pathogenic

0.98

BayesDel_addAF

Pathogenic

0.58

BayesDel_noAF

Pathogenic

0.59

CADD

Pathogenic

(source)

DANN

Uncertain

1.0

DEOGEN2

Pathogenic

0.98

Eigen

Pathogenic

1.0

Eigen_PC

Pathogenic

0.85

FATHMM_MKL

Uncertain

0.96

LIST_S2

Pathogenic

0.99

M_CAP

Pathogenic

0.61

MetaRNN

Pathogenic

0.99

MetaSVM

Pathogenic

0.86

MutationAssessor

Pathogenic

4.5

PhyloP100

7.7

PrimateAI

Uncertain

0.70

PROVEAN

Pathogenic

-9.0

REVEL

Pathogenic

0.97

Sift

Pathogenic

0.0

Sift4G

Pathogenic

0.0010

Polyphen

1.0

Vest4

0.99

MutPred

0.93

Loss of helix (P = 0.079)

MVP

0.99

MPC

0.70

ClinPred

1.0

GERP RS

4.9

Varity_R

0.99

gMVP

0.96

Mutation Taster

=1/99

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

1.0

SpliceAI score (max)

0.33

Details are displayed if max score is > 0.2

DS_AL_spliceai

0.33

Position offset: 0

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over