Genetic Variant ADA:n.*837T>A (chr20-44620297-A-T) – ACMG Classification: Likely_pathogenic (7 pts)

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PVS1_ModeratePM3PP4_ModeratePM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.1078+2T>A (NM_000022.4) variant in ADA occurs within the canonical splice donor site (+2) of intron 11. It is predicted to cause skipping of biologically relevant exon by SpliceAI (Δ score = Donor Loss = 0.97); however, due to the location, it is NOT predicted to undergo NMD. There aren't known downstream pathogenic variants; PVS1_Moderate.This variant is absent from gnomAD v2.1.1 (PM2_Supporting). At least one patient present: Reduced ADA enzyme activity in patient cells (1pt) + Increased dAdo nucleotides (dATP or dAXP) in pretreatment erythrocytes (2pts), reaching 3 points, PP4_Moderate.This variant has been detected in 02 individuals with ADA SCID. One of them is compound heterozygous with c.955-958delGAAG, p.E320RfsX6, a frameshift termination, which is at least LP according to SCID VCEP. Phase is unknown, so 0.5 pt; The second one is compound heterozygous, for c.482G > A, p.W161X (Also at least LP according to SCID VCEP). Phase is not shown. 0.5pts. Total is 1 pt, PM3_Moderate (PMIDs: 32307643 and 26255240).In summary, this variant is classified as a Likely Pathogenic for autosomal recessive SCID based on ACMG/AMP criteria applied, as specified by the ClinGen SCID VCEP (specification version 1.0): PM2_Supporting, PVS1_Strong, PP4_Moderate, and PM3_Moderate. LINK:https://erepo.genome.network/evrepo/ui/classification/CA409118270/MONDO:0007064/114

Frequency

Genomes: not found (cov: 32)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

ADA
ENST00000696038.1 non_coding_transcript_exon

Scores

Splicing: ADA: 1.000

Clinical Significance

Likely pathogenic reviewed by expert panel P:2

Conservation

PhyloP100: 2.50

Publications

0 publications found

Variant links:

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]

ADA links:

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]

PKIG links:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 7 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.

PM3

For more information check the summary or visit ClinGen Evidence Repository.

PP4

For more information check the summary or visit ClinGen Evidence Repository.

Variant Effect in Transcripts

ACMG analysis was done for transcript: ENST00000696038.1. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein
ADA	NM_000022.4	MANE Select	c.1078+2T>A	splice_donor intron	N/A	NP_000013.2
ADA	NM_001322051.2		c.1006+2T>A	splice_donor intron	N/A	NP_001308980.1
ADA	NM_001322050.2		c.673+2T>A	splice_donor intron	N/A	NP_001308979.1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein
ADA	ENST00000696038.1		n.*837T>A	non_coding_transcript_exon	Exon 9 of 9	ENSP00000512344.1
ADA	ENST00000696038.1		n.*837T>A	3_prime_UTR	Exon 9 of 9	ENSP00000512344.1
ADA	ENST00000372874.9	TSL:1 MANE Select	c.1078+2T>A	splice_donor intron	N/A	ENSP00000361965.4

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461310

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

727030

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33472

American (AMR)

AF:

0.00

AC:

AN:

44722

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26126

East Asian (EAS)

AF:

0.00

AC:

AN:

39698

South Asian (SAS)

AF:

0.00

AC:

AN:

86238

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53418

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5620

European-Non Finnish (NFE)

AF:

9.00e-7

AC:

AN:

1111656

Other (OTH)

AF:

0.00

AC:

AN:

60360

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

Cov.:

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: reviewed by expert panel

LINK: link

Submissions by phenotype

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

Pathogenic:2

Jan 23, 2024

ClinGen Severe Combined Immunodeficiency Variant Curation Expert Panel, ClinGen

Significance:Likely pathogenic

Review Status:reviewed by expert panel

Collection Method:curation

The c.1078+2T>A (NM_000022.4) variant in ADA occurs within the canonical splice donor site (+2) of intron 11. It is predicted to cause skipping of biologically relevant exon by SpliceAI (Δ score = Donor Loss = 0.97); however, due to the location, it is NOT predicted to undergo NMD. There aren't known downstream pathogenic variants; PVS1_Moderate. This variant is absent from gnomAD v2.1.1 (PM2_Supporting). At least one patient present: Reduced ADA enzyme activity in patient cells (1pt) + Increased dAdo nucleotides (dATP or dAXP) in pretreatment erythrocytes (2pts), reaching 3 points, PP4_Moderate. This variant has been detected in 02 individuals with ADA SCID. One of them is compound heterozygous with c.955-958delGAAG, p.E320RfsX6, a frameshift termination, which is at least LP according to SCID VCEP. Phase is unknown, so 0.5 pt; The second one is compound heterozygous, for c.482G > A, p.W161X (Also at least LP according to SCID VCEP). Phase is not shown. 0.5pts. Total is 1 pt, PM3_Moderate (PMIDs: 32307643 and 26255240). In summary, this variant is classified as a Likely Pathogenic for autosomal recessive SCID based on ACMG/AMP criteria applied, as specified by the ClinGen SCID VCEP (specification version 1.0): PM2_Supporting, PVS1_Strong, PP4_Moderate, and PM3_Moderate.

May 14, 2018

Counsyl

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com.

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Benign

-0.15

CADD

Uncertain

(source)

DANN

Uncertain

0.97

Eigen

Pathogenic

0.74

Eigen_PC

Uncertain

0.50

FATHMM_MKL

Uncertain

0.94

PhyloP100

2.5

GERP RS

4.7

Mutation Taster

=11/89

disease causing (ClinVar)

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

0.97

Details are displayed if max score is > 0.2

DS_DL_spliceai

0.97

Position offset: 2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over