Is ADA p.Arg76Gln (c.227G>A) pathogenic?

ADA p.Arg76Gln (c.227G>A) is classified Uncertain significance in ADA (ClinVar, Single submitter, 2 submitters; last evaluated 2023-12-11). AlphaMissense: likely benign (0.1138); Very rare (popmax 0.00878%, sas); 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.Arg76Gln (c.227G>A) in the general population?

ADA p.Arg76Gln (c.227G>A) is very rare (popmax 0.00878%, sas) (gnomAD).

What do computational predictors say about ADA p.Arg76Gln (c.227G>A)?

AlphaMissense predicts likely benign (score 0.1138) — an in-silico prediction, not a clinical call.

ADA p.Arg76Gln

Q: What condition is associated with ADA p.Arg76Gln (c.227G>A)?

ADA p.Arg76Gln (c.227G>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.227G>A · rs374983783 · VCV1024523

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 2 submitters

AlphaMissense

likely benign

0.1138 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00878%, sas)

Missense predictors

1/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

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

Computational evidence

Protein change
AlphaMissense	0.1138	likely benign
REVEL	0.806	moderately pathogenic-leaning
SaProt	LLR -7.75	tolerated
⇒ REVEL calls this damaging; AlphaMissense and SaProt do not.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 7.6	GERP 1.4, phastCons 1
Regional constraint	o/e 0.94	unconstrained · MANE · 32 kb · p 0.21 · regional, not allelic
Overall
CADD	32.0	PHRED · no single calibrated threshold — expert panels disagree

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

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00878% South Asian · 8/91,076 alleles

Filtering AF 0.00437% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00312%

Overall 0.00118% 19/1,613,988 alleles · very rare

Ancestry group	Frequency	1 in
South Asiangrpmax	0.00878%	11,385
Finnishnot grpmax-eligible	0.00312%	32,010
East Asian	0.00223%	44,880
European (non-Finnish)	0.000678%	147,505

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.Arg76Gln
Coding: c.227G>A
MANE Select: NM_000022
dbSNP: rs374983783
Type: single nucleotide variant
Location: chr20:44626591 (GRCh38)
Gene constraint: LOEUF 1.184 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 96.81 · 2 PDB
Residue 76: a UniProt-annotated variant site (in adascid); 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.Arg76Trp Conflicting classifications of pathogenicity ★ ⚠ 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
ADA p.Ala329Val 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-arg76gln (accessed [today's date]).

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