16-56336799-C-T

Variant names:

• chr16-56336799-C-T
• NM_020988.3:c.662C>T

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.662C>T​(p.Ala221Val) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,356 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: GNAO1 NM_020988.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.16

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, 0.935

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GNAO1	NM_020988.3	c.662C>T	p.Ala221Val	missense_variant	Exon 6 of 9	ENST00000262493.12	NP_066268.1
GNAO1	NM_138736.3	c.662C>T	p.Ala221Val	missense_variant	Exon 6 of 8		NP_620073.2
GNAO1	XM_011523003.4	c.536C>T	p.Ala179Val	missense_variant	Exon 6 of 9		XP_011521305.1
GNAO1	XR_007064866.1	n.1409C>T		non_coding_transcript_exon_variant	Exon 6 of 9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GNAO1	ENST00000262493.12	c.662C>T	p.Ala221Val	missense_variant	Exon 6 of 9	1	NM_020988.3	ENSP00000262493.6

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461356 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727028

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

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

Feb 18, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 221 of the GNAO1 protein (p.Ala221Val). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with GNAO1-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 expected to disrupt GNAO1 protein function with a positive predictive value of 80%. 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	0.96
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.39
CADD	Pathogenic	28
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.84	D;D;.;.;.
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.84
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.93	.;D;D;D;D
M_CAP	Uncertain	0.25	D
MetaRNN	Pathogenic	0.94	D;D;D;D;D
MetaSVM	Pathogenic	0.93	D
MutationAssessor	Uncertain	2.7	M;M;M;.;.
PrimateAI	Pathogenic	0.90	D
PROVEAN	Uncertain	-3.5	D;.;D;.;.
REVEL	Pathogenic	0.92
Sift	Uncertain	0.0070	D;.;D;.;.
Sift4G	Uncertain	0.027	D;.;D;.;.
Polyphen		1.0	D;D;D;.;.
Vest4		0.77
MutPred		0.81		Gain of sheet (P = 0.1539);Gain of sheet (P = 0.1539);Gain of sheet (P = 0.1539);.;.;
MVP		0.94
MPC		2.6
ClinPred		0.98	D
GERP RS		5.3
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: chr16-56370711;