rs121908730

chr20-44626598-C-A

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PM5 PP3 PP5_Moderate

The NM_000022.4(ADA):c.220G>T(p.Gly74Cys) variant causes a missense, splice region 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. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G74V) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: ADA NM_000022.4 missense, splice_region
• Scores: Splicing: ADA: 0.9749
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1 O:1
• Conservation: PhyloP100: 7.43

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]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr20-44626597-C-A is described in ClinVar as [Pathogenic]. Clinvar id is 1977.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 20-44626598-C-A is Pathogenic according to our data. Variant chr20-44626598-C-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 68257.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chr20-44626598-C-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ADA	NM_000022.4	c.220G>T	p.Gly74Cys	missense_variant, splice_region_variant	4/12	ENST00000372874.9
ADA	NM_001322051.2	c.220G>T	p.Gly74Cys	missense_variant, splice_region_variant	4/11
ADA	NM_001322050.2	c.-70G>T		splice_region_variant, 5_prime_UTR_variant	4/11
ADA	NR_136160.2	n.312G>T		splice_region_variant, non_coding_transcript_exon_variant	4/11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ADA	ENST00000372874.9	c.220G>T	p.Gly74Cys	missense_variant, splice_region_variant	4/12	1	NM_000022.4	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-negative, due to adenosine deaminase deficiency Pathogenic:1 Other:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Aug 13, 2023	- -
not provided, no classification provided	literature only	UniProtKB/Swiss-Prot	-	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.89
BayesDel_addAF	Pathogenic	0.55	D
BayesDel_noAF	Pathogenic	0.56
Cadd	Pathogenic	33
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.95	D;D
Eigen	Pathogenic	0.85
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D
M_CAP	Pathogenic	0.43	D
MetaRNN	Pathogenic	0.99	D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Pathogenic	3.5	H;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.58	T
PROVEAN	Pathogenic	-8.6	D;D
REVEL	Pathogenic	0.93
Sift	Pathogenic	0.0	D;D
Sift4G	Pathogenic	0.0010	D;D
Polyphen		1.0	D;.
Vest4		0.93
MutPred		0.93		Loss of catalytic residue at P70 (P = 0.0694);Loss of catalytic residue at P70 (P = 0.0694);
MVP		0.95
MPC		0.65
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.93
gMVP		0.81

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.97
dbscSNV1_RF	Pathogenic	0.88
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

Publications

LitVar

Other links and lift over

dbSNP: rs121908730; hg19: chr20-43255239;