Is ADA p.Arg313Gln (c.938G>A) pathogenic?

ADA p.Arg313Gln (c.938G>A) is classified Uncertain significance in ADA (ClinVar, Expert panel, 3 submitters; last evaluated 2024-04-23). AlphaMissense: likely benign (0.0853); Ultra-rare (popmax 0.0164%, mid); Associated with severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-negative, due to adenosine deaminase deficiency.

How common is ADA p.Arg313Gln (c.938G>A) in the general population?

ADA p.Arg313Gln (c.938G>A) is ultra-rare (popmax 0.0164%, mid) (gnomAD).

What do computational predictors say about ADA p.Arg313Gln (c.938G>A)?

AlphaMissense predicts likely benign (score 0.0853) — an in-silico prediction, not a clinical call.

ADA p.Arg313Gln

Q: What condition is associated with ADA p.Arg313Gln (c.938G>A)?

ADA p.Arg313Gln (c.938G>A) is associated with severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-negative, due to adenosine deaminase deficiency (ClinVar).

Q: How is Severe combined immunodeficiency due to adenosine deaminase deficiency inherited?

Typically Autosomal recessive (Orphanet). A genetic counselor can assess individual risk for a family.

c.938G>A · rs747500864 · VCV1038658

Uncertain significance Expert panel

Classification

Uncertain significance

ClinVar

Review

Expert panel ★★★☆

ClinVar · 3 submitters

AlphaMissense

likely benign

0.0853 · ACMG-weighted

gnomAD v4.1

Rare

ultra-rare (popmax 0.0164%, mid)

Missense predictors

0/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

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

ClinGen expert panel — Severe Combined Immunodeficiency Disease VCEP

Uncertain Significance for adenosine deaminase deficiency. Applied ACMG criteria (verbatim):

PM2_Supporting

Curation rationale (ClinGen, verbatim)

The c.938G>A (NM_000022.4) variant in ADA is a missense variant predicted to cause substitution of Arginine by Glutamine at amino acid 313 (p.Arg313Gln). The filtering allele frequency (the upper threshold of the 95% CI of 2/91080 alleles) of the c.938G>A variant in ADA is 0.000003650 for South Asian chromosomes by gnomAD v4, which is lower than the ClinGen SCID VCEP threshold (<0.0001742) for PM2_Supporting, and therefore meets this criterion (PM2_Supporting). No homozygotes have been observed in gnomAD. No homozygotes have been observed in gnomAD. Another missense variant [c.937C>T, p.Arg313Trp] in the same codon has been reported; however, the ClinGen SCID VCEP classified this variant as VUS (PM5 not met). To our knowledge, this variant has not been reported in the literature in individuals affected with ADA-related conditions or in functional studies. Due to insufficient evidence, this variant is classified as a variant of uncertain significance for autosomal recessive SCID based on ACMG/AMP criteria applied, as specified by the ClinGen SCID VCEP (specification version 1.0): PM2_Supporting.

ClinGen Evidence Repository → · reported verbatim, not re-tallied by Sugi Variant.

Computational evidence

Protein change
AlphaMissense	0.0853	likely benign
REVEL	0.26	benign-leaning
SaProt	LLR -8.29	tolerated
⇒ AlphaMissense, REVEL and SaProt all call this tolerated.
Splicing
SpliceAI	<0.2	no splice effect predicted · four deltas, not one · how we know
Constraint at this position
Conservation	phyloP -7.1	GERP -3.4
Regional constraint	o/e 0.94	unconstrained · MANE · 32 kb · p 0.21 · regional, not allelic
Overall
CADD	1.127	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean tolerated — a triage signal, not a reclassification

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0164% Middle Eastern · 1/6,082 alleles

Filtering AF 0.000365% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00026%

Overall 0.000929% 15/1,614,012 alleles · ultra-rare exomes 14/1,461,884 · genomes 1/152,128 · joint denominator

Ancestry group	Frequency	1 in
Middle Easterngrpmax	0.0164%	6,082
South Asian	0.0022%	45,540
Admixed American	0.00167%	59,998
Remaining individualsnot grpmax-eligible	0.0016%	62,488
African / African-American	0.00134%	74,882
European (non-Finnish)	0.000763%	131,115

Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.

Variant & gene context

Gene: ADA
Protein: p.Arg313Gln
Coding: c.938G>A
MANE Select: NM_000022
dbSNP: rs747500864
Type: single nucleotide variant
Location: chr20:44621055 (GRCh38)
Gene constraint: LOEUF 1.184 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 96.81 · 2 PDB
Residue 313: an α-helix

Full ADA gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

severe combined immunodeficiency, autosomal recessive, T cell-negative, B cell-negative, NK cell-negative, due to adenosine deaminase deficiency — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Severe combined immunodeficiency due to adenosine deaminase deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy, Neonatal
Prevalence: 1-9 / 1 000 000 (Europe)

Similar variants

ADA p.Arg313Trp Uncertain significance ★★★ ⚠ same residue
ADA p.Arg313= Likely benign ★ same residue
ADA c.1078+2T>A Likely pathogenic ★★★ same condition
ADA c.219-2A>G Likely pathogenic ★★★ same condition
ADA c.363-2A>G Likely pathogenic ★★★ same condition
ADA c.606+1G>T Likely pathogenic ★★★ same condition
ADA c.975+1G>A Pathogenic ★★★ same condition
ADA c.976-1G>C Pathogenic ★★★ same condition

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/ada-p-arg313gln (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown