rs114025668

Positions:

• chr20-44623042-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_000022.4(ADA):​c.643G>A​(p.Ala215Thr) variant causes a missense change. The variant allele was found at a frequency of 0.0000613 in 1,614,108 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Synonymous variant affecting the same amino acid position (i.e. A215A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00028 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000039 (0 hom.)
• Consequence: ADA NM_000022.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts P:1 U:7 O:1
• Conservation: PhyloP100: 5.20

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

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 4 uncertain in NM_000022.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.919

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
ADA	NM_000022.4	c.643G>A	p.Ala215Thr	missense_variant	7/12	ENST00000372874.9
ADA	NM_001322050.2	c.238G>A	p.Ala80Thr	missense_variant	6/11
ADA	NM_001322051.2	c.607-112G>A		intron_variant
ADA	NR_136160.2	n.735G>A		non_coding_transcript_exon_variant	7/11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
ADA	ENST00000372874.9	c.643G>A	p.Ala215Thr	missense_variant	7/12	1	NM_000022.4	P4

Frequencies

GnomAD3 genomes AF: 0.000276 AC: 42 AN: 152160 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.000676

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000458

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000588

Gnomad OTH AF: 0.00143

GnomAD3 exomes AF: 0.0000994 AC: 25 AN: 251422 Hom.: 0 AF XY: 0.0000736 AC XY: 10 AN XY: 135890

Gnomad AFR exome AF: 0.00111

Gnomad AMR exome AF: 0.0000867

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000264

Gnomad OTH exome AF: 0.000163

GnomAD4 exome AF: 0.0000390 AC: 57 AN: 1461828 Hom.: 0 Cov.: 33 AF XY: 0.0000358 AC XY: 26 AN XY: 727210

Gnomad4 AFR exome AF: 0.000836

Gnomad4 AMR exome AF: 0.0000894

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000348

Gnomad4 FIN exome AF: 0.0000187

Gnomad4 NFE exome AF: 0.0000153

Gnomad4 OTH exome AF: 0.0000662

GnomAD4 genome AF: 0.000276 AC: 42 AN: 152280 Hom.: 0 Cov.: 33 AF XY: 0.000269 AC XY: 20 AN XY: 74454

Gnomad4 AFR AF: 0.000674

Gnomad4 AMR AF: 0.000458

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000588

Gnomad4 OTH AF: 0.00142

Alfa AF: 0.0000888 Hom.: 0

Bravo AF: 0.000382

ESP6500AA AF: 0.000908 AC: 4

ESP6500EA AF: 0.00 AC: 0

ExAC AF: 0.000107 AC: 13

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Pathogenic:1 Uncertain:7 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-negative, due to adenosine deaminase deficiency Uncertain:6 Other:1

Uncertain significance, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 01, 2022	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Fulgent Genetics, Fulgent Genetics	Apr 26, 2022	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Dec 04, 2017	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Center for Genomic Medicine, King Faisal Specialist Hospital and Research Center	Apr 04, 2024	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Aug 19, 2022	This sequence change replaces alanine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 215 of the ADA protein (p.Ala215Thr). This variant is present in population databases (rs114025668, gnomAD 0.07%). This missense change has been observed in individual(s) with partial ADA deficiency without SCID (PMID: 2166947, 9108404, 9225964, 9758612, 14499267). ClinVar contains an entry for this variant (Variation ID: 1967). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt ADA protein function. Experimental studies have shown that this missense change affects ADA function (PMID: 2166947, 9108404, 9361033, 11067872). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -
not provided, no classification provided	literature only	UniProtKB/Swiss-Prot	-	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Sep 05, 2021	- -

Partial adenosine deaminase deficiency Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Aug 01, 1990

- -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Dec 07, 2020

Variant summary: ADA c.643G>A (p.Ala215Thr) results in a non-conservative amino acid change located in the Adenosine/AMP deaminase domain (IPR001365) of the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. 4/4 computational tools predict no significant impact on normal splicing. However, at least one publication reports experimental evidence that this variant affects mRNA splicing resulting in induction of exon 7 skipping in approximately 50% of cells (Ozsahin_1997) but a residual low level (10-15%) skipping of exon 7 was also observed in normal cells. Therefore, the exact impact of this splicing phenomenon on ADA activity in-vivo is not clear. The variant allele was found at a frequency of 9.9e-05 in 251422 control chromosomes. This frequency is not significantly higher than expected for a pathogenic variant in ADA causing Severe Combined Immunodeficiency Syndrome (9.9e-05 vs 0.0014), allowing no conclusion about variant significance. c.643G>A has been not been reported in the literature in individuals affected with Severe Combined Immunodeficiency Syndrome, but has been observed in clinically asymptomatic individuals presenting with a partial ADA deficiency in-vitro (example, Hirschhorn_1990, Hirschhorn_1997, Ozsahin_1997). These report(s) do not provide unequivocal conclusions about association of the variant with Severe Combined Immunodeficiency Syndrome. At least one publication reports experimental evidence evaluating an impact on protein function. The most pronounced variant effect results in <10% of normal ADA enzyme activity (example, Jiang_1997, Richard_2007, Arredondo-Vega_1998). Two clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. All laboratories classified the variant as uncertain significance citing overlapping evidence utilized in the context of this evaluation. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.50
BayesDel_addAF	Pathogenic	0.28	D
BayesDel_noAF	Pathogenic	0.55
CADD	Pathogenic	29
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.97	D
Eigen	Uncertain	0.60
Eigen_PC	Uncertain	0.39
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Uncertain	0.97	D
M_CAP	Pathogenic	0.32	D
MetaRNN	Pathogenic	0.92	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.3	H
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.53	T
PROVEAN	Uncertain	-3.7	D
REVEL	Pathogenic	0.89
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0040	D
Polyphen		1.0	D
Vest4		0.95
MVP		0.90
MPC		0.62
ClinPred		0.68	D
GERP RS		3.9
Varity_R		0.90
gMVP		0.94

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

Publications

LitVar

Other links and lift over

dbSNP: rs114025668; hg19: chr20-43251683;