rs797045599

chr16-56336817-C-T

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PS1_Moderate PM1 PP2 PP3_Strong PP5_Very_Strong

The NM_020988.3(GNAO1):c.680C>T(p.Ala227Val) variant causes a missense change involving the alteration of a conserved nucleotide. 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 Likely pathogenic (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Likely pathogenicin UniProt. Synonymous variant affecting the same amino acid position (i.e. A227A) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: GNAO1 NM_020988.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 7.89

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 Pathogenic. Variant got 17 ACMG points.

• PS1: Transcript NM_020988.3 (GNAO1) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in UniProt
• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_020988.3
• PP2: Missense variant where missense usually causes diseases, GNAO1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.96
• PP5: Variant 16-56336817-C-T is Pathogenic according to our data. Variant chr16-56336817-C-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 211088.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr16-56336817-C-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GNAO1	NM_020988.3	c.680C>T	p.Ala227Val	missense_variant	6/9	ENST00000262493.12
GNAO1	NM_138736.3	c.680C>T	p.Ala227Val	missense_variant	6/8
GNAO1	XM_011523003.4	c.554C>T	p.Ala185Val	missense_variant	6/9
GNAO1	XR_007064866.1	n.1427C>T		non_coding_transcript_exon_variant	6/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GNAO1	ENST00000262493.12	c.680C>T	p.Ala227Val	missense_variant	6/9	1	NM_020988.3	P1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Data not reliable, filtered out with message: AC0 AF: 0.00 AC: 0 AN: 1461174 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726920

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.: 34

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Developmental and epileptic encephalopathy, 17 Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Génétique des Maladies du Développement, Hospices Civils de Lyon	Jun 21, 2016	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Genetic Services Laboratory, University of Chicago	May 22, 2015	- -

Early infantile epileptic encephalopathy with suppression bursts Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Sep 27, 2022

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. ClinVar contains an entry for this variant (Variation ID: 211088). This missense change has been observed in individual(s) with early onset epileptic encephalopathy (PMID: 25966631). In at least one individual the variant was observed to be de novo. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 227 of the GNAO1 protein (p.Ala227Val). Experimental studies have shown that this missense change affects GNAO1 function (PMID: 28747448). For these reasons, this variant has been classified as Pathogenic. -

Developmental and epileptic encephalopathy, 17;C4479569:Neurodevelopmental disorder with involuntary movements Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Oct 31, 2018

- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Jul 15, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 30838255, 27072799, 25966631, 28747448, 28202424, 28628939, 27787898, 32382396, 33298085, 27535533) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
Cadd	Pathogenic	30
Dann	Pathogenic	1.0
DEOGEN2	Pathogenic	0.94	D;D;.;.;.
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Uncertain	0.94	D
M_CAP	Pathogenic	0.38	D
MetaRNN	Pathogenic	0.96	D;D;D;D;D
MetaSVM	Pathogenic	0.97	D
MutationAssessor	Pathogenic	3.9	H;H;H;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.90	D
PROVEAN	Uncertain	-3.5	D;.;D;.;.
REVEL	Pathogenic	0.89
Sift	Pathogenic	0.0	D;.;D;.;.
Sift4G	Pathogenic	0.0010	D;.;D;.;.
Polyphen		1.0	D;D;D;.;.
Vest4		0.96
MutPred		0.85		Gain of sheet (P = 0.1208);Gain of sheet (P = 0.1208);Gain of sheet (P = 0.1208);.;.;
MVP		0.92
MPC		2.5
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.96
gMVP		0.95

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: rs797045599; hg19: chr16-56370729;