12-89525204-C-A

Variant names:

• chr12-89525204-C-A
• NM_172240.3:c.16G>T

Variant summary

Our verdict is Pathogenic. Variant got 13 ACMG points: 13P and 0B. PVS1 PM2 PP3 PP5_Moderate

The NM_172240.3(POC1B):​c.16G>T​(p.Glu6*) variant causes a stop gained, splice region change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: POC1B NM_172240.3 stop_gained, splice_region
• Scores: Splicing: ADA: 0.9996
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 2.84

Genes affected

POC1B (HGNC:30836): (POC1 centriolar protein B) POC1 proteins contain an N-terminal WD40 domain and a C-terminal coiled coil domain and are part of centrosomes. They play an important role in basal body and cilia formation. This gene encodes one of the two POC1 proteins found in humans. Mutation in this gene result in autosomal-recessive cone-rod dystrophy. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Oct 2014]

POC1B-GALNT4 (HGNC:42957): (POC1B-GALNT4 readthrough) This locus represents naturally occurring transcripts that splice the 5' exons of the POC1B (POC1 centriolar protein homolog B) gene on chromosome 12 to the GALNT4 (UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 4) gene, which is located within a POC1B intron. Alternative splicing results in two transcript variants, one of which encodes a fusion isoform that shares sequence identity with the products of each individual gene. [provided by RefSeq, Dec 2010]

POC1B-AS1 (HGNC:52949): (POC1B antisense RNA 1)

ACMG classification

Verdict is Pathogenic. Variant got 13 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 31 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 12-89525204-C-A is Pathogenic according to our data. Variant chr12-89525204-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 3685609.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POC1B	NM_172240.3	c.16G>T	p.Glu6*	stop_gained, splice_region_variant	Exon 2 of 12	ENST00000313546.8	NP_758440.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
POC1B	ENST00000313546.8	c.16G>T	p.Glu6*	stop_gained, splice_region_variant	Exon 2 of 12	1	NM_172240.3	ENSP00000323302.3
POC1B-GALNT4	ENST00000548729.5	c.16G>T	p.Glu6*	stop_gained, splice_region_variant	Exon 2 of 3	2		ENSP00000447852.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 29

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Dec 25, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Glu6*) in the POC1B gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in POC1B are known to be pathogenic (PMID: 25018096, 29220607). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with POC1B-related conditions. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.48
CADD	Pathogenic	54
DANN	Uncertain	1.0
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Benign	0.70	D
Vest4		0.22
GERP RS		4.6

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.61		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.61		Position offset: -3

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr12-89918981;