2-86027523-C-T

Position:

• chr2-86027523-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP2 PP3

The NM_015425.6(POLR1A):​c.5063G>A​(p.Gly1688Glu) variant causes a missense, splice region change. The variant allele was found at a frequency of 0.00000205 in 1,461,222 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 Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: POLR1A NM_015425.6 missense, splice_region
• Scores: Splicing: ADA: 0.9993
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.99

Genes affected

POLR1A (HGNC:17264): (RNA polymerase I subunit A) The protein encoded by this gene is the largest subunit of the RNA polymerase I complex. The encoded protein represents the catalytic subunit of the complex, which transcribes DNA into ribosomal RNA precursors. Defects in this gene are a cause of the Cincinnati type of acrofacial dysostosis. [provided by RefSeq, May 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), POLR1A. . Gene score misZ 2.9485 (greater than the threshold 3.09). Trascript score misZ 4.9691 (greater than threshold 3.09). GenCC has associacion of gene with acrofacial dysostosis Cincinnati type, choanal atresia-hearing loss-cardiac defects-craniofacial dysmorphism syndrome.
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
POLR1A	NM_015425.6	c.5063G>A	p.Gly1688Glu	missense_variant, splice_region_variant	34/34	ENST00000263857.11	NP_056240.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
POLR1A	ENST00000263857.11	c.5063G>A	p.Gly1688Glu	missense_variant, splice_region_variant	34/34	1	NM_015425.6	ENSP00000263857	P2
POLR1A	ENST00000409681.1	c.4880G>A	p.Gly1627Glu	missense_variant, splice_region_variant	34/34	5		ENSP00000386300	A2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000802 AC: 2 AN: 249488 Hom.: 0 AF XY: 0.00000739 AC XY: 1 AN XY: 135372

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000290

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000556

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: 1461222 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727018

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000224

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome Cov.: 32

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 17, 2021

This sequence change replaces glycine with glutamic acid at codon 1688 of the POLR1A protein (p.Gly1688Glu). The glycine residue is highly conserved and there is a moderate physicochemical difference between glycine and glutamic acid. This variant is present in population databases (rs771079145, ExAC 0.01%). This variant has not been reported in the literature in individuals affected with POLR1A-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Not Available"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Not Available"). 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	Pathogenic	0.76
BayesDel_addAF	Pathogenic	0.21	D
BayesDel_noAF	Pathogenic	0.23
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.50	T;T
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.77
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.93	D;D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.81	D;D
MetaSVM	Uncertain	0.26	D
MutationAssessor	Pathogenic	3.2	M;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.72	T
PROVEAN	Pathogenic	-6.8	D;D
REVEL	Pathogenic	0.69
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0	D;D
Polyphen		1.0	D;.
Vest4		0.78
MutPred		0.57		Gain of disorder (P = 0.0637);.;
MVP		0.71
MPC		1.1
ClinPred		0.99	D
GERP RS		4.9
Varity_R		0.92
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.87
SpliceAI score (max)		0.19		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: rs771079145; hg19: chr2-86254646;