chr16-56336741-G-A

Position:

• chr16-56336741-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP2 PP3_Moderate PP5

The ENST00000262493.12(GNAO1):​c.604G>A​(p.Val202Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,459,214 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 Conflicting classifications of pathogenicity (no stars). Synonymous variant affecting the same amino acid position (i.e. V202V) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: GNAO1 ENST00000262493.12 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 9.99

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 Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in ENST00000262493.12
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), GNAO1. . Gene score misZ 3.1919 (greater than the threshold 3.09). Trascript score misZ 4.549 (greater than threshold 3.09). GenCC has associacion of gene with developmental and epileptic encephalopathy, 17, neurodevelopmental disorder with involuntary movements, developmental and epileptic encephalopathy, movement disorder.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.921
• PP5: Variant 16-56336741-G-A is Pathogenic according to our data. Variant chr16-56336741-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 545591.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=2}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GNAO1	NM_020988.3	c.604G>A	p.Val202Ile	missense_variant	6/9	ENST00000262493.12	NP_066268.1
GNAO1	NM_138736.3	c.604G>A	p.Val202Ile	missense_variant	6/8		NP_620073.2
GNAO1	XM_011523003.4	c.478G>A	p.Val160Ile	missense_variant	6/9		XP_011521305.1
GNAO1	XR_007064866.1	n.1351G>A		non_coding_transcript_exon_variant	6/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GNAO1	ENST00000262493.12	c.604G>A	p.Val202Ile	missense_variant	6/9	1	NM_020988.3	ENSP00000262493	P1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1459214 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 725786

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: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

Bravo AF: 0.00000378

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

GNAO1-related disorder Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Rady Children's Institute for Genomic Medicine, Rady Children's Hospital San Diego

May 11, 2020

This variant has not been previously reported or functionally characterized in the literature to our knowledge. It is absent from the gnomAD population database and thus is presumed to be rare. The c.604G>A (p.Val202Ile) variant affects a highly conserved amino acid and is predicted by multiple in silico tools to have a deleterious effect on protein function. A recurrent missense variant at the adjacent amino acid residue (c.607G>A, p.G203R) has been reported as a de novo change in individuals with phenotypes that include epileptic encephalopathy, developmental delay, chorea, dystrophy, dystonia (PMID: 28628939, 28973083, 29100083, 28688840, 28202424, 25966631, 23993195). Analysis of the parental samples was negative for the variant, indicating this variant likely occurred as a de novo event. Based on the available evidence, the c.604G>A (p.Val202Ile) variant is classified as Likely Pathogenic. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Jun 12, 2019

Not observed in large population cohorts (Lek et al., 2016); In silico analysis, which includes protein predictors and evolutionary conservation, supports that this variant does not alter protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Neurodevelopmental disorder with involuntary movements Uncertain:1

Uncertain significance, criteria provided, single submitter

research

HudsonAlpha Institute for Biotechnology, HudsonAlpha Institute for Biotechnology

Apr 16, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.84
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.070
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.57	D;D;.;.
Eigen	Pathogenic	0.98
Eigen_PC	Pathogenic	0.92
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	0.97	.;D;D;D
M_CAP	Pathogenic	0.37	D
MetaRNN	Pathogenic	0.92	D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.9	H;H;H;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.84	D
PROVEAN	Benign	-0.95	N;.;N;.
REVEL	Pathogenic	0.73
Sift	Pathogenic	0.0	D;.;D;.
Sift4G	Uncertain	0.015	D;.;D;.
Polyphen		0.99	D;D;D;.
Vest4		0.52
MutPred		0.86		Gain of catalytic residue at V202 (P = 0.0681);Gain of catalytic residue at V202 (P = 0.0681);Gain of catalytic residue at V202 (P = 0.0681);.;
MVP		0.89
MPC		2.4
ClinPred		1.0	D
GERP RS		5.3
Varity_R		0.81
gMVP		0.86

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: rs1297388989; hg19: chr16-56370653;