12-89525132-C-T

Variant names:

• chr12-89525132-C-T
• rs1456154895
• NM_172240.3:c.88G>A

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_172240.3(POC1B):​c.88G>A​(p.Gly30Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,690 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G30D) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: POC1B NM_172240.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: -0.139

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 Likely_benign. Variant got -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.05852151).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POC1B	NM_172240.3	c.88G>A	p.Gly30Ser	missense_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.88G>A	p.Gly30Ser	missense_variant	Exon 2 of 12	1	NM_172240.3	ENSP00000323302.3
POC1B-GALNT4	ENST00000548729.5	c.88G>A	p.Gly30Ser	missense_variant	Exon 2 of 3	2		ENSP00000447852.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251310 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135870

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461690 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 727158

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cone-rod dystrophy 20 Uncertain:1

Mar 28, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Uncertain:1

Aug 20, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with serine at codon 30 of the POC1B protein (p.Gly30Ser). The glycine residue is moderately conserved and there is a small physicochemical difference between glycine and serine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with POC1B-related conditions. 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 not expected to disrupt POC1B protein function. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.11
BayesDel_addAF	Benign	-0.23	T
BayesDel_noAF	Benign	-0.39
CADD	Benign	13
DANN	Benign	0.96
DEOGEN2	Benign	0.017	T;.;.
Eigen	Benign	-0.91
Eigen_PC	Benign	-0.92
FATHMM_MKL	Benign	0.015	N
LIST_S2	Benign	0.79	T;T;T
M_CAP	Uncertain	0.10	D
MetaRNN	Benign	0.059	T;T;T
MetaSVM	Benign	-0.82	T
PROVEAN	Benign	0.69	N;N;N
REVEL	Benign	0.028
Sift	Benign	0.86	T;T;T
Sift4G	Benign	0.67	T;T;T
Polyphen		0.039	B;B;.
Vest4		0.23
MutPred		0.35		Gain of catalytic residue at L26 (P = 0);Gain of catalytic residue at L26 (P = 0);Gain of catalytic residue at L26 (P = 0);
MVP		0.43
MPC		0.062
ClinPred		0.36	T
GERP RS		-0.73
Varity_R		0.072
gMVP		0.28

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: rs1456154895; hg19: chr12-89918909;