chr20-58903792-G-A

Position:

• chr20-58903792-G-A

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Strong PM2 PP5_Very_Strong

The NM_000516.7(GNAS):​c.432+1G>A variant causes a splice donor, intron 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. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: GNAS NM_000516.7 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:5 O:1
• Conservation: PhyloP100: 9.40

Genes affected

GNAS (HGNC:4392): (GNAS complex locus) This locus has a highly complex imprinted expression pattern. It gives rise to maternally, paternally, and biallelically expressed transcripts that are derived from four alternative promoters and 5' exons. Some transcripts contain a differentially methylated region (DMR) at their 5' exons, and this DMR is commonly found in imprinted genes and correlates with transcript expression. An antisense transcript is produced from an overlapping locus on the opposite strand. One of the transcripts produced from this locus, and the antisense transcript, are paternally expressed noncoding RNAs, and may regulate imprinting in this region. In addition, one of the transcripts contains a second overlapping ORF, which encodes a structurally unrelated protein - Alex. Alternative splicing of downstream exons is also observed, which results in different forms of the stimulatory G-protein alpha subunit, a key element of the classical signal transduction pathway linking receptor-ligand interactions with the activation of adenylyl cyclase and a variety of cellular reponses. Multiple transcript variants encoding different isoforms have been found for this gene. Mutations in this gene result in pseudohypoparathyroidism type 1a, pseudohypoparathyroidism type 1b, Albright hereditary osteodystrophy, pseudopseudohypoparathyroidism, McCune-Albright syndrome, progressive osseus heteroplasia, polyostotic fibrous dysplasia of bone, and some pituitary tumors. [provided by RefSeq, Aug 2012]

GNAS (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.10042194 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 20-58903792-G-A is Pathogenic according to our data. Variant chr20-58903792-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 446491.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr20-58903792-G-A is described in Lovd as [Pathogenic]. Variant chr20-58903792-G-A is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GNAS	NM_000516.7	c.432+1G>A		splice_donor_variant, intron_variant		ENST00000371085.8	NP_000507.1
GNAS	NM_016592.5	c.*338+1G>A		splice_donor_variant, intron_variant		ENST00000371075.7	NP_057676.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GNAS	ENST00000371085.8	c.432+1G>A		splice_donor_variant, intron_variant		1	NM_000516.7	ENSP00000360126.3
GNAS	ENST00000371075.7	c.*338+1G>A		splice_donor_variant, intron_variant		1	NM_016592.5	ENSP00000360115.3
GNAS	ENST00000676826.2	c.2364+1G>A		splice_donor_variant, intron_variant				ENSP00000504675.2
GNAS	ENST00000371102.8	c.2319+1G>A		splice_donor_variant, intron_variant		5		ENSP00000360143.4
GNAS	ENST00000354359.12	c.435+1G>A		splice_donor_variant, intron_variant		1		ENSP00000346328.7
GNAS	ENST00000371095.7	c.390+1G>A		splice_donor_variant, intron_variant		1		ENSP00000360136.3
GNAS	ENST00000470512.6	c.258+1G>A		splice_donor_variant, intron_variant		5		ENSP00000499552.2
GNAS	ENST00000480232.6	c.258+1G>A		splice_donor_variant, intron_variant		5		ENSP00000499545.2
GNAS	ENST00000663479.2	c.258+1G>A		splice_donor_variant, intron_variant				ENSP00000499353.2
GNAS	ENST00000462499.6	c.213+1G>A		splice_donor_variant, intron_variant		2		ENSP00000499758.2
GNAS	ENST00000467227.6	c.213+1G>A		splice_donor_variant, intron_variant		3		ENSP00000499681.2
GNAS	ENST00000478585.6	c.213+1G>A		splice_donor_variant, intron_variant		2		ENSP00000499762.2
GNAS	ENST00000481039.6	c.213+1G>A		splice_donor_variant, intron_variant		5		ENSP00000499767.2
GNAS	ENST00000485673.6	c.213+1G>A		splice_donor_variant, intron_variant		5		ENSP00000499334.2
GNAS	ENST00000488546.6	c.213+1G>A		splice_donor_variant, intron_variant		5		ENSP00000499332.2
GNAS	ENST00000492907.6	c.213+1G>A		splice_donor_variant, intron_variant		3		ENSP00000499443.2
GNAS	ENST00000453292.7	c.*293+1G>A		splice_donor_variant, intron_variant		5		ENSP00000392000.2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 34

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:5 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Pseudopseudohypoparathyroidism Pathogenic:2 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Pathogenic, criteria provided, single submitter	clinical testing	Rady Children's Institute for Genomic Medicine, Rady Children's Hospital San Diego	Dec 20, 2017	The c.2361+1G>A splice-site variant affects the canonical splice donor site of intron 5 and is thus predicted to be a loss of function mutation. It has been reported as a de novo heterozygous change in a patient with pseudopseudohypoparathyroidism (Wilson et al, 1997) and is absent from the ExAC and gnomAD population databases. Sanger sequencing of the parental samples was negative for the variant indicating that this variant likely represents a de novo change in the patient. However, low level parental mosaicism cannot be excluded. Based on the combined evidence, c.2361+1G>A is classified as a pathogenic variant. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	May 08, 2023	- -

not provided Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Dec 09, 2020	For these reasons, this variant has been classified as Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has been observed in individual(s) with pseudopseudohypoparathyroidism (PMID: 7853365). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 446491). This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in intron 5 of the GNAS gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in GNAS are known to be pathogenic (PMID: 11784876, 23281139, 23796510, 25802881). -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Sep 01, 2023	Canonical splice site variant predicted to result in an in-frame loss of the adjacent exon in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 29072892, 23281139, 25525159, 23884777, 31624069, 30577886, 31019026, 31886927, 25802881, 7853365, 35296306) -

Inborn genetic diseases Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 29, 2016

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.39
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.98	D
GERP RS		5.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.93		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.27		Position offset: -36
DS_DL_spliceai		0.93		Position offset: -1

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1555889131; hg19: chr20-57478847;