rs121908740

Variant names:

• chr20-44623054-G-A
• rs121908740
• NM_000022.4:c.631C>T

Your query was ambiguous. Multiple possible variants found:

• chr20-44623054-G-A
• chr20-44623054-G-T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM5 PM3 PP1_Moderate

This summary comes from the ClinGen Evidence Repository: NM_000022.4:c.631C>T is a missense variant predicted to cause substitution of Arginine by Cysteine at amino acid 211 (p. Arg211Cys). The highest population minor allele frequency in gnomAD v4 is 0.0005167 (31/60000) in Admixed American population (PM2_Supporting, BS1, and BA1 are not met). The variant has been reported to segregate with SCID in 2 affected family members from 1 family (PP1_moderate; PMID :8051429). Patient was found heterozygous for R211C & L107P which is classified as likely pathogenic by SCID VCEP (1 pt.) (PM3) (PMID:2166947).Another missense variant [c.632G>A, p.Arg211His)] in the same codon has been classified as pathogenic for SCID by the ClinGen SCID VCEP (PM5).In summary, this variant meets the criteria to be classified as a 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: PP1_moderate,PM3,PM5(VCEP specifications version 1). LINK:https://erepo.genome.network/evrepo/ui/classification/CA115285/MONDO:0007064/114

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000035 (0 hom.)
• Consequence: ADA NM_000022.4 missense
• Clinical Significance: Likely pathogenic reviewed by expert panel P:10 U:1 O:1
• Conservation: PhyloP100: 5.17
• Publications: 7 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 6 ACMG points.

• PM3: For more information check the summary or visit ClinGen Evidence Repository.
• PM5: For more information check the summary or visit ClinGen Evidence Repository.
• PP1: For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ADA	NM_000022.4	c.631C>T	p.Arg211Cys	missense_variant	Exon 7 of 12	ENST00000372874.9	NP_000013.2
ADA	NM_001322050.2	c.226C>T	p.Arg76Cys	missense_variant	Exon 6 of 11		NP_001308979.1
ADA	NR_136160.2	n.723C>T		non_coding_transcript_exon_variant	Exon 7 of 11
ADA	NM_001322051.2	c.607-124C>T		intron_variant	Intron 6 of 10		NP_001308980.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ADA	ENST00000372874.9	c.631C>T	p.Arg211Cys	missense_variant	Exon 7 of 12	1	NM_000022.4	ENSP00000361965.4
ADA	ENST00000695995.1	c.241C>T	p.Arg81Cys	missense_variant	Exon 4 of 9			ENSP00000512318.1
ADA	ENST00000696038.1	n.*377C>T		non_coding_transcript_exon_variant	Exon 7 of 9			ENSP00000512344.1
ADA	ENST00000696038.1	n.*377C>T		3_prime_UTR_variant	Exon 7 of 9			ENSP00000512344.1
ADA	ENST00000695991.1	c.217-124C>T		intron_variant	Intron 3 of 7			ENSP00000512314.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152200 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000147

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000127 AC: 32 AN: 251340 AF XY: 0.000110

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000694

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.000815

GnomAD4 exome AF: 0.0000349 AC: 51 AN: 1461770 Hom.: 0 Cov.: 33 AF XY: 0.0000330 AC XY: 24 AN XY: 727182

African (AFR) AF: 0.00 AC: 0 AN: 33476

American (AMR) AF: 0.000693 AC: 31 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53410

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.0000126 AC: 14 AN: 1111938

Other (OTH) AF: 0.0000828 AC: 5 AN: 60382

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152200 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74354

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 41450

American (AMR) AF: 0.00 AC: 0 AN: 15280

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

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

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68030

Other (OTH) AF: 0.00 AC: 0 AN: 2094

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.0000472 Hom.: 0

Bravo AF: 0.0000340

ExAC AF: 0.000107 AC: 13

Asia WGS AF: 0.000289 AC: 1 AN: 3478

EpiCase AF: 0.0000545

EpiControl AF: 0.0000593

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:10 Uncertain:1 Other:1

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:8 Uncertain:1 Other:1

-

UniProtKB/Swiss-Prot

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Sep 16, 2020

Natera, Inc.

Significance: Likely pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Aug 10, 2021

Genome-Nilou Lab

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Feb 01, 2024

Laboratory of Medical Genetics, National & Kapodistrian University of Athens

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: curation

- -

Mar 25, 2025

Institute of Medical Genetics and Applied Genomics, University Hospital Tübingen

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Dec 23, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with cysteine, which is neutral and slightly polar, at codon 211 of the ADA protein (p.Arg211Cys). This variant is present in population databases (rs121908740, gnomAD 0.07%). This missense change has been observed in individual(s) with adenosine deaminase deficiency (PMID: 2166947, 8051429, 9616253). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 1966). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is not expected to disrupt ADA protein function with a negative predictive value of 80%. Experimental studies have shown that this missense change affects ADA function (PMID: 9361033, 9758612). This variant disrupts the p.Arg211 amino acid residue in ADA. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 1974554, 9414266, 9758612, 26376800). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Jan 10, 2024

ClinGen Severe Combined Immunodeficiency Variant Curation Expert Panel, ClinGen

Significance: Likely pathogenic

Review Status: reviewed by expert panel

Collection Method: curation

NM_000022.4:c.631C>T is a missense variant predicted to cause substitution of Arginine by Cysteine at amino acid 211 (p. Arg211Cys). The highest population minor allele frequency in gnomAD v4 is 0.0005167 (31/60000) in Admixed American population (PM2_Supporting, BS1, and BA1 are not met). The variant has been reported to segregate with SCID in 2 affected family members from 1 family (PP1_moderate; PMID :8051429). Patient was found heterozygous for R211C & L107P which is classified as likely pathogenic by SCID VCEP (1 pt.) (PM3) (PMID: 2166947).Another missense variant [c.632G>A, p.Arg211His)] in the same codon has been classified as pathogenic for SCID by the ClinGen SCID VCEP (PM5). In summary, this variant meets the criteria to be classified as a 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: PP1_moderate,PM3,PM5(VCEP specifications version 1). -

Mar 25, 2024

Baylor Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 10, 2018

Counsyl

Significance: Uncertain significance

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. -

Nov 01, 2018

Illumina Laboratory Services, Illumina

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The ADA c.631C>T (p.Arg211Cys) variant was first reported by Hirschhorn et al. (1990) in a child with partial adenosine deaminase (ADA) deficiency. This patient was compound heterozygous for p.Arg211Cys and a second missense variant, and had approximately 8% residual ADA activity in lymphoid cells. The p.Arg211Cys variant was subsequently identified in a compound heterozygous state with a second deletion variant in two siblings with ADA deficiency and combined immunodeficiency, with no detectable ADA activity. The p.Arg211Cys variant was also detected in a heterozygous state in the mother, two additional siblings, and in a patient's child, all of whom had normal or below normal ADA activity (Shovlin et al. 1994). Control data are unavailable for this variant, but it is reported at a frequency of 0.00078 in the Latino population of the Exome Aggregation Consortium. Expression studies in COS cells by Jiang et al. (1997) showed that the p.Arg211Cys variant resulted in residual ADA activity of approximately 4% of normal. Another variant at this position, p.Arg211His, has also been seen in patients with ADA deficiency (Akeson et al. 1988; Arredondo-Vega et al. 1998). Based on the collective evidence, the p.Arg211Cys variant is classified as likely pathogenic for adenosine deaminase deficiency. This variant was observed by ICSL as part of a predisposition screen in an ostensibly healthy population. -

Partial adenosine deaminase deficiency Pathogenic:1

Sep 01, 1994

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Severe combined immunodeficiency disease Pathogenic:1

May 06, 2025

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: ADA c.631C>T (p.Arg211Cys) results in a non-conservative amino acid change located in the adenosine deaminase domain (IPR001365) of the encoded protein sequence. Algorithms developed to predict the effect of missense changes on protein structure and function all suggest that this variant is likely to be disruptive. The variant allele was found at a frequency of 0.00013 in 251340 control chromosomes, predominantly at a frequency of 0.00069 within the Latino subpopulation in the gnomAD database. This frequency is not significantly higher than estimated for a pathogenic variant in ADA causing Severe Combined Immunodeficiency (0.00013 vs 0.0014), allowing no conclusion about variant significance. c.631C>T has been reported in the literature as a compound heterozygous genotype in an individual with partial ADA deficiency, detected as 8% ADA activity in lymphoid cells, and in two siblings affected with late onset severe combined immunodeficiency with ADA deficiency, where the variant segregated with disease in the family (e.g., Hirschhorn_1990, Shovlin_1994). It was also found in a homozygous SCID case identified during newborn screening (Ricci_2024). These data indicate that the variant is likely to be associated with disease. A different variant affecting the same codon has been classified as likely pathogenic/pathogenic by our lab (c.632G>A, p.Arg211His), supporting the critical relevance of codon 211 to ADA protein function. Several publications report evidence evaluating an impact on protein function (e.g., Hirschhorn_1990, Jiang_1997, Arredondo-Vega_1998), and experiments expressing the variant in an in vitro model system found that the variant results in <5% of normal activity. The following publications have been ascertained in the context of this evaluation (PMID: 9758612, 8051429, 2166947, 9361033, 38636590). ClinVar contains an entry for this variant (Variation ID: 1966). Based on the evidence outlined above, the variant was classified as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Pathogenic	0.23	D
BayesDel_noAF	Pathogenic	0.46
CADD	Pathogenic	33
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.94	D
Eigen	Uncertain	0.29
Eigen_PC	Uncertain	0.23
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Uncertain	0.92	D
M_CAP	Pathogenic	0.54	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.99	D
MutationAssessor	Uncertain	2.3	M
PhyloP100		5.2
PrimateAI	Uncertain	0.56	T
PROVEAN	Pathogenic	-7.2	D
REVEL	Pathogenic	0.88
Sift	Uncertain	0.014	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.95
MutPred		0.87		Loss of methylation at R211 (P = 0.0329);
MVP		0.95
MPC		0.61
ClinPred		0.79	D
GERP RS		4.0
Varity_R		0.80
gMVP		0.91
Mutation Taster		=12/88	disease causing (ClinVar)

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: rs121908740; hg19: chr20-43251695;