NM_020988.3:c.8G>A

Variant names:

• chr16-56192243-G-A
• NM_020988.3:c.8G>A

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_020988.3(GNAO1):​c.8G>A​(p.Cys3Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: GNAO1 NM_020988.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.53

Genes affected

GNAO1 (HGNC:4389): (G protein subunit alpha o1) The protein encoded by this gene represents the alpha subunit of the Go heterotrimeric G-protein signal-transducing complex. Defects in this gene are a cause of early-onset epileptic encephalopathy. Two transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Aug 2015]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the GNAO1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 70 curated pathogenic missense variants (we use a threshold of 10). The gene has 43 curated benign missense variants. Gene score misZ: 3.1919 (above the threshold of 3.09). Trascript score misZ: 4.549 (above the threshold of 3.09). GenCC associations: The gene is linked to developmental and epileptic encephalopathy, 17, neurodevelopmental disorder with involuntary movements, developmental and epileptic encephalopathy, movement disorder.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.896

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GNAO1	NM_020988.3	c.8G>A	p.Cys3Tyr	missense_variant	Exon 1 of 9	ENST00000262493.12	NP_066268.1
GNAO1	NM_138736.3	c.8G>A	p.Cys3Tyr	missense_variant	Exon 1 of 8		NP_620073.2
GNAO1	XR_007064866.1	n.755G>A		non_coding_transcript_exon_variant	Exon 1 of 9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GNAO1	ENST00000262493.12	c.8G>A	p.Cys3Tyr	missense_variant	Exon 1 of 9	1	NM_020988.3	ENSP00000262493.6

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Data not reliable, filtered out with message: AC0;AS_VQSR AF: 0.00 AC: 0 AN: 1428464 Hom.: 0 Cov.: 28 AF XY: 0.00 AC XY: 0 AN XY: 710810

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Early infantile epileptic encephalopathy with suppression bursts Uncertain:1

Aug 11, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces cysteine, which is neutral and slightly polar, with tyrosine, which is neutral and polar, at codon 3 of the GNAO1 protein (p.Cys3Tyr). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with neurodevelopmental disorders (PMID: 33994118). 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 expected to disrupt GNAO1 protein function with a positive predictive value of 95%. 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	0.93
BayesDel_addAF	Pathogenic	0.49	D
BayesDel_noAF	Pathogenic	0.47
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.78	D;.;D;.;T;.
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.83
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.97	.;D;D;D;D;D
M_CAP	Pathogenic	0.58	D
MetaRNN	Pathogenic	0.90	D;D;D;D;D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Pathogenic	3.9	H;.;H;H;.;.
PrimateAI	Pathogenic	0.88	D
PROVEAN	Pathogenic	-6.1	D;.;.;D;.;.
REVEL	Pathogenic	0.91
Sift	Pathogenic	0.0	D;.;.;D;.;.
Sift4G	Uncertain	0.015	D;.;.;D;D;.
Polyphen		1.0	D;.;D;D;.;.
Vest4		0.64
MutPred		0.48		Gain of phosphorylation at C3 (P = 0.0884);Gain of phosphorylation at C3 (P = 0.0884);Gain of phosphorylation at C3 (P = 0.0884);Gain of phosphorylation at C3 (P = 0.0884);Gain of phosphorylation at C3 (P = 0.0884);Gain of phosphorylation at C3 (P = 0.0884);
MVP		0.94
MPC		3.6
ClinPred		1.0	D
GERP RS		4.8
Varity_R		0.90
gMVP		0.97

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr16-56226155;