20-58910740-GCT-ACA

Variant names:

• chr20-58910740-GCT-ACA
• NM_080425.4:c.3025_3027delGCTinsACA
• GNAS p.Ala1009Thr

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PS1_Moderate PM1 PM5 PP3

The NM_000516.7(GNAS):​c.1096_1098delGCTinsACA​(p.Ala366Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type MNV, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A366S) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GNAS NM_000516.7 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 9.52
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• McCune-Albright syndrome

  Inheritance: AD, Unknown Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, Ambry Genetics, G2P
• progressive osseous heteroplasia

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE, NO_KNOWN Submitted by: Orphanet, Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae)
• pseudohypoparathyroidism type 1A

  Inheritance: AD, Mitochondrial Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Ambry Genetics, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• pseudohypoparathyroidism type 1B

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp, G2P
• pseudohypoparathyroidism type 1C

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Orphanet, Genomics England PanelApp
• pseudopseudohypoparathyroidism

  Inheritance: AD, Mitochondrial Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, G2P, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PS1: Transcript NM_000516.7 (GNAS) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 8 uncertain in NM_000516.7
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr20-58910740-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 15944.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP3: No computational evidence supports a deleterious effect, but strongly conserved according to phyloP

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000516.7. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GNAS	NM_080425.4	MANE Plus Clinical	c.3025_3027delGCTinsACA	p.Ala1009Thr	missense	N/A	NP_536350.2	Q5JWF2-1
	GNAS	NM_000516.7	MANE Select	c.1096_1098delGCTinsACA	p.Ala366Thr	missense	N/A	NP_000507.1	P63092-1
	GNAS	NM_016592.5	MANE Plus Clinical	c.*1002_*1004delGCTinsACA		3_prime_UTR	Exon 13 of 13	NP_057676.1	O95467-1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GNAS	ENST00000371100.9	TSL:5 MANE Plus Clinical	c.3025_3027delGCTinsACA	p.Ala1009Thr	missense	N/A	ENSP00000360141.3	Q5JWF2-1
	GNAS	ENST00000371085.8	TSL:1 MANE Select	c.1096_1098delGCTinsACA	p.Ala366Thr	missense	N/A	ENSP00000360126.3	P63092-1
	GNAS	ENST00000676826.2		c.3028_3030delGCTinsACA	p.Ala1010Thr	missense	N/A	ENSP00000504675.2	A0A7I2V5R6

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		9.5

Splicing

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr20-57485795;