chr20-44624205-G-T

Variant names:

• chr20-44624205-G-T
• rs1555844395
• NM_000022.4:c.603C>A

Variant summary

Our verdict is Likely pathogenic. The variant received 9 ACMG points: 9P and 0B. PVS1 PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.603C>A (p.Tyr201Ter) (NM_000022.4) variant in ADA is a nonsense variant predicted to cause a premature stop codon in biologically-relevant-exon 6/12 leading to nonsense-mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1_Met). The highest population minor allele frequency in gnomAD v4 is 0.00001166 (1/85734 alleles) in South Asian population, which is lower than the ClinGen SCID VCEP threshold (<0.0001742) for PM2_Supporting, and therefore meets this criterion (PM2_Supporting). There are no publications for this variant in the literature. As per the SCID VCEP specifications and the Bayesian interpretation of the ACMG/AMP combining rules, 1 very strong and 1 supporting criteria results in a Likely Pathogenic classification. In summary, this variant meets the criteria to be classified as Likely Pathogenic variant for autosomal recessive severe combined immunodeficiency due to ADA deficiency based on the ACMG/AMP criteria applied, as specified by the ClinGen SCID VCEP: PM2_supporting,PVS1 (VCEP specifications version 1). LINK:https://erepo.genome.network/evrepo/ui/classification/CA409120739/MONDO:0007064/114

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: ADA NM_000022.4 stop_gained
• Clinical Significance: Likely pathogenic reviewed by expert panel P:3
• Conservation: PhyloP100: -0.911
• Publications: 1 publications found

Genes affected

ADA (HGNC:186): (adenosine deaminase) This gene encodes an enzyme that catalyzes the hydrolysis of adenosine to inosine in the purine catabolic pathway. Various mutations have been described for this gene and have been linked to human diseases related to impaired immune function such as severe combined immunodeficiency disease (SCID) which is the result of a deficiency in the ADA enzyme. In ADA-deficient individuals there is a marked depletion of T, B, and NK lymphocytes, and consequently, a lack of both humoral and cellular immunity. Conversely, elevated levels of this enzyme are associated with congenital hemolytic anemia. [provided by RefSeq, Sep 2019]

PKIG (HGNC:9019): (cAMP-dependent protein kinase inhibitor gamma) This gene encodes a member of the protein kinase inhibitor family. Studies of a similar protein in mice suggest that this protein acts as a potent competitive cAMP-dependent protein kinase inhibitor, and is a predominant form of inhibitor in various tissues. The encoded protein may be involved in osteogenesis. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2013]

ACMG classification

Our verdict: Likely_pathogenic. The variant received 9 ACMG points.

• PVS1: For more information check the summary or visit ClinGen Evidence Repository.
• PM2: For more information check the summary or visit ClinGen Evidence Repository.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000022.4. 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
	ADA	NM_000022.4	MANE Select	c.603C>A	p.Tyr201*	stop_gained	Exon 6 of 12	NP_000013.2
	ADA	NM_001322051.2		c.603C>A	p.Tyr201*	stop_gained	Exon 6 of 11	NP_001308980.1
	ADA	NM_001322050.2		c.198C>A	p.Tyr66*	stop_gained	Exon 5 of 11	NP_001308979.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ADA	ENST00000372874.9	TSL:1 MANE Select	c.603C>A	p.Tyr201*	stop_gained	Exon 6 of 12	ENSP00000361965.4
	ADA	ENST00000537820.2	TSL:1	c.603C>A	p.Tyr201*	stop_gained	Exon 6 of 11	ENSP00000441818.1
	ADA	ENST00000696038.1		n.*349C>A		non_coding_transcript_exon	Exon 6 of 9	ENSP00000512344.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1458990 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 725600

African (AFR) AF: 0.00 AC: 0 AN: 33422

American (AMR) AF: 0.00 AC: 0 AN: 44282

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26010

East Asian (EAS) AF: 0.00 AC: 0 AN: 39646

South Asian (SAS) AF: 0.0000117 AC: 1 AN: 85734

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53210

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1110688

Other (OTH) AF: 0.00 AC: 0 AN: 60232

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:3

Revision: reviewed by expert panel

Submissions by phenotype

Severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-negative, due to adenosine deaminase deficiency Pathogenic:3

Mar 12, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Tyr201*) in the ADA gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in ADA are known to be pathogenic (PMID: 26255240, 26376800). This variant is not present in population databases (gnomAD no frequency). This premature translational stop signal has been observed in individual(s) with severe combined immunodeficiency due to adenosine deaminase deficiency (PMID: 26255240). ClinVar contains an entry for this variant (Variation ID: 1406981). For these reasons, this variant has been classified as Pathogenic.

Apr 04, 2024

ClinGen Severe Combined Immunodeficiency Variant Curation Expert Panel, ClinGen

Significance: Likely pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

The c.603C>A (p.Tyr201Ter) (NM_000022.4) variant in ADA is a nonsense variant predicted to cause a premature stop codon in biologically-relevant-exon 6/12 leading to nonsense-mediated decay in a gene in which loss-of-function is an established disease mechanism (PVS1_Met). The highest population minor allele frequency in gnomAD v4 is 0.00001166 (1/85734 alleles) in South Asian population, which is lower than the ClinGen SCID VCEP threshold (<0.0001742) for PM2_Supporting, and therefore meets this criterion (PM2_Supporting). There are no publications for this variant in the literature. As per the SCID VCEP specifications and the Bayesian interpretation of the ACMG/AMP combining rules, 1 very strong and 1 supporting criteria results in a Likely Pathogenic classification. In summary, this variant meets the criteria to be classified as Likely Pathogenic variant for autosomal recessive severe combined immunodeficiency due to ADA deficiency based on the ACMG/AMP criteria applied, as specified by the ClinGen SCID VCEP: PM2_supporting,PVS1 (VCEP specifications version 1).

Sep 08, 2023

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	0.060
CADD	Uncertain	24
DANN	Benign	0.94
Eigen	Benign	-0.51
Eigen_PC	Benign	-0.95
FATHMM_MKL	Benign	0.34	N
PhyloP100		-0.91
Vest4		0.92
GERP RS		-9.7
Mutation Taster		=2/198	disease causing (fs/PTC)

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

Other links and lift over

dbSNP: rs1555844395; hg19: chr20-43252846;