rs879253813

Positions:

• chr3-136250563-G-A
• chr3-136250563-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP5

The ENST00000251654.9(PCCB):​c.183+5G>A variant causes a splice donor 5th base, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000412 in 1,457,486 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: PCCB ENST00000251654.9 splice_donor_5th_base, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:3 U:1
• Conservation: PhyloP100: 3.57

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-136250563-G-A is Pathogenic according to our data. Variant chr3-136250563-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 217896.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Pathogenic=2, Uncertain_significance=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
PCCB	NM_000532.5	c.183+5G>A		splice_donor_5th_base_variant, intron_variant		ENST00000251654.9	NP_000523.2
PCCB	NM_001178014.2	c.183+5G>A		splice_donor_5th_base_variant, intron_variant			NP_001171485.1
PCCB	XM_011512873.2	c.183+5G>A		splice_donor_5th_base_variant, intron_variant			XP_011511175.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
PCCB	ENST00000251654.9	c.183+5G>A		splice_donor_5th_base_variant, intron_variant		1	NM_000532.5	ENSP00000251654	P2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000427 AC: 1 AN: 234344 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 129136

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: 0.0000333

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000412 AC: 6 AN: 1457486 Hom.: 0 Cov.: 31 AF XY: 0.00000690 AC XY: 5 AN XY: 724808

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: 0.0000698

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:3 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Propionic acidemia Pathogenic:3 Uncertain:1

Pathogenic, criteria provided, single submitter	research	Institute of Medical Genetics and Genomics, Sir Ganga Ram Hospital	-	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Dec 21, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 25, 2023	This sequence change falls in intron 1 of the PCCB gene. It does not directly change the encoded amino acid sequence of the PCCB protein. It affects a nucleotide within the consensus splice site. This variant is present in population databases (no rsID available, gnomAD 0.003%). This variant has been observed in individual(s) with propionic acidemia (PMID: 27227689). ClinVar contains an entry for this variant (Variation ID: 217896). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Aug 17, 2018	The PCCB c.183+5G>A variant has been reported in a total of three pediatric individuals with propionic acidemia, including in two in a homozygous state and in one in a compound heterozygous state. None of the patients harboring this variant survived (Gupta et al. 2016). The c.183+5G>A variant is not found in the 1000 Genomes Project, the Exome Sequencing Project, or the Exome Aggregation Consortium. The evidence for this variant is limited. The c.183+5G>A variant is therefore classified as a variant of unknown significance but suspicious for pathogenicity for propionic acidemia. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.20
CADD	Benign	22
DANN	Benign	0.95
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.40		Position offset: 15
DS_DL_spliceai		0.98		Position offset: -5

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs879253813; hg19: chr3-135969405;