X-24699458-G-A

Variant names:

• chrX-24699458-G-A
• rs747434011
• NM_001330360.2:c.77G>A

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4 BS2

The NM_001330360.2(POLA1):​c.77G>A​(p.Arg26Gln) variant causes a missense change. The variant allele was found at a frequency of 0.00000469 in 1,066,010 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 2 hemizygotes in GnomAD. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 22)
  • Exomes 𝑓: 0.0000047 (0 hom. 2 hem.)
• Consequence: POLA1 NM_001330360.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.01

Genes affected

POLA1 (HGNC:9173): (DNA polymerase alpha 1, catalytic subunit) This gene encodes the catalytic subunit of DNA polymerase, which together with a regulatory and two primase subunits, forms the DNA polymerase alpha complex. The catalytic subunit plays an essential role in the initiation of DNA replication. [provided by RefSeq, Mar 2010]

ACMG classification

Verdict is Likely_benign. Variant got -5 ACMG points.

• BP4: Computational evidence support a benign effect (MetaRNN=0.3784098).
• BS2: High Hemizygotes in GnomAdExome4 at 2 XL gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
POLA1	NM_001330360.2	c.77G>A	p.Arg26Gln	missense_variant	Exon 2 of 37	ENST00000379068.8	NP_001317289.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
POLA1	ENST00000379068.8	c.77G>A	p.Arg26Gln	missense_variant	Exon 2 of 37	5	NM_001330360.2	ENSP00000368358.3

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome AF: 0.00000469 AC: 5 AN: 1066010 Hom.: 0 Cov.: 26 AF XY: 0.00000591 AC XY: 2 AN XY: 338428

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: 0.0000207

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000486

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 22

ExAC AF: 0.00000828 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Jun 11, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has not been reported in the literature in individuals affected with POLA1-related conditions. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 20 of the POLA1 protein (p.Arg20Gln). 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: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). 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	0.72
BayesDel_addAF	Benign	-0.088	T
BayesDel_noAF	Benign	-0.36
CADD	Pathogenic	27
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.71	.;.;D
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Uncertain	0.94	D;D;D
M_CAP	Benign	0.059	D
MetaRNN	Benign	0.38	T;T;T
MetaSVM	Benign	-0.92	T
MutationAssessor	Uncertain	2.3	.;.;M
PrimateAI	Uncertain	0.51	T
PROVEAN	Uncertain	-3.0	D;.;D
REVEL	Benign	0.28
Sift	Pathogenic	0.0	D;.;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;.;D
Vest4		0.43
MutPred		0.38		Gain of loop (P = 0.0312);.;.;
MVP		0.76
MPC		1.2
ClinPred		0.95	D
GERP RS		5.0
Varity_R		0.86
gMVP		0.35

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs747434011; hg19: chrX-24717575;