chr20-36927228-A-AC

Variant names:

• chr20-36927228-A-AC
• rs515726146
• NM_015474.4:c.649_650insG

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The ENST00000646673.2(SAMHD1):​c.649_650insG​(p.Phe217CysfsTer2) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000031 in 1,613,984 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: SAMHD1 ENST00000646673.2 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2 O:1
• Conservation: PhyloP100: 8.85
• Publications: 3 publications found

Genes affected

SAMHD1 (HGNC:15925): (SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1) This gene may play a role in regulation of the innate immune response. The encoded protein is upregulated in response to viral infection and may be involved in mediation of tumor necrosis factor-alpha proinflammatory responses. Mutations in this gene have been associated with Aicardi-Goutieres syndrome. [provided by RefSeq, Mar 2010]

SAMHD1 Gene-Disease associations (from GenCC):

• Aicardi-Goutieres syndrome 5

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, PanelApp Australia, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, G2P
• Moyamoya disease

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp
• Aicardi-Goutieres syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial chilblain lupus

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• chilblain lupus 2

  Inheritance: AD Classification: LIMITED Submitted by: Ambry Genetics
• chilblain lupus

  Inheritance: AD Classification: NO_KNOWN Submitted by: Illumina

ACMG classification

Our verdict: Pathogenic. The variant received 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 20-36927228-A-AC is Pathogenic according to our data. Variant chr20-36927228-A-AC is described in ClinVar as Pathogenic. ClinVar VariationId is 126413.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: ENST00000646673.2. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SAMHD1	NM_015474.4	MANE Select	c.649_650insG	p.Phe217CysfsTer2	frameshift	Exon 6 of 16	NP_056289.2
	SAMHD1	NM_001363729.2		c.649_650insG	p.Phe217CysfsTer2	frameshift	Exon 6 of 15	NP_001350658.1
	SAMHD1	NM_001363733.2		c.649_650insG	p.Phe217CysfsTer2	frameshift	Exon 6 of 16	NP_001350662.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SAMHD1	ENST00000646673.2	MANE Select	c.649_650insG	p.Phe217CysfsTer2	frameshift	Exon 6 of 16	ENSP00000493536.2
	SAMHD1	ENST00000262878.5	TSL:1	c.649_650insG	p.Phe217CysfsTer2	frameshift	Exon 6 of 15	ENSP00000262878.5
	SAMHD1	ENST00000643918.1		c.649_650insG	p.Phe217CysfsTer2	frameshift	Exon 6 of 16	ENSP00000493928.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152146 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.000288

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251460 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.0000992

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461838 Hom.: 0 Cov.: 31 AF XY: 0.00000413 AC XY: 3 AN XY: 727224

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.000115 AC: 3 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39694

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111980

Other (OTH) AF: 0.00 AC: 0 AN: 60388

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152146 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74330

African (AFR) AF: 0.00 AC: 0 AN: 41444

American (AMR) AF: 0.00 AC: 0 AN: 15252

Ashkenazi Jewish (ASJ) AF: 0.000288 AC: 1 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5204

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10608

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68020

Other (OTH) AF: 0.00 AC: 0 AN: 2090

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

ClinVar submissions as Germline

Significance: Pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
2	-	-	Aicardi-Goutieres syndrome 5 (3)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		8.9
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs515726146; hg19: chr20-35555631;