16-56192291-T-A

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM2 PM5 PP2 PP3_Strong

The NM_020988.3(GNAO1):c.56T>A(p.Ile19Asn) 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 (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I19M) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: GNAO1 NM_020988.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.65

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 9 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr16-56192292-T-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 2500270.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant where missense usually causes diseases, GNAO1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.95

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GNAO1	NM_020988.3	c.56T>A	p.Ile19Asn	missense_variant	1/9	ENST00000262493.12
GNAO1	NM_138736.3	c.56T>A	p.Ile19Asn	missense_variant	1/8
GNAO1	XR_007064866.1	n.803T>A		non_coding_transcript_exon_variant	1/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GNAO1	ENST00000262493.12	c.56T>A	p.Ile19Asn	missense_variant	1/9	1	NM_020988.3	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 29

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Mar 26, 2022

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. 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. This variant has not been reported in the literature in individuals affected with GNAO1-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces isoleucine, which is neutral and non-polar, with asparagine, which is neutral and polar, at codon 19 of the GNAO1 protein (p.Ile19Asn). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.32	D
BayesDel_noAF	Pathogenic	0.22
Cadd	Pathogenic	29
Dann	Uncertain	0.99
DEOGEN2	Pathogenic	0.93	D;.;D;.;T;.
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.73
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Pathogenic	0.88	D
MetaRNN	Pathogenic	0.95	D;D;D;D;D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Pathogenic	4.4	H;.;H;H;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.88	D
PROVEAN	Pathogenic	-4.7	D;.;.;D;.;.
REVEL	Pathogenic	0.95
Sift	Pathogenic	0.0	D;.;.;D;.;.
Sift4G	Pathogenic	0.0	D;.;.;D;D;.
Polyphen		0.97	D;.;D;D;.;.
Vest4		0.82
MutPred		0.80		Gain of ubiquitination at K21 (P = 0.0545);Gain of ubiquitination at K21 (P = 0.0545);Gain of ubiquitination at K21 (P = 0.0545);Gain of ubiquitination at K21 (P = 0.0545);Gain of ubiquitination at K21 (P = 0.0545);Gain of ubiquitination at K21 (P = 0.0545);
MVP		0.90
MPC		3.5
ClinPred		1.0	D
GERP RS		4.8
Varity_R		0.98
gMVP		1.0

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: chr16-56226203;