Is ADA p.Arg101Gly (c.301C>G) pathogenic?

ADA p.Arg101Gly (c.301C>G) is classified Likely pathogenic in ADA (ClinVar, Single submitter, 1 submitter; last evaluated 2022-08-31). AlphaMissense: likely pathogenic (0.9684); Very rare (popmax 0.000169%, nfe); 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.Arg101Gly (c.301C>G) in the general population?

ADA p.Arg101Gly (c.301C>G) is very rare (popmax 0.000169%, nfe) (gnomAD).

What do computational predictors say about ADA p.Arg101Gly (c.301C>G)?

AlphaMissense predicts likely pathogenic (score 0.9684) — an in-silico prediction, not a clinical call.

ADA p.Arg101Gly

Q: What condition is associated with ADA p.Arg101Gly (c.301C>G)?

ADA p.Arg101Gly (c.301C>G) 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.301C>G · rs121908717 · VCV971097

Likely pathogenic Single submitter

Classification

Likely pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.9684 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.000169%, nfe)

Missense predictors

3/3 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	0.9684	likely pathogenic ✓ concordant with ClinVar · top 6% in ADA
REVEL	0.897	moderately pathogenic-leaning
SaProt	LLR -16.37	damaging
⇒ AlphaMissense, REVEL and SaProt all call this damaging.
Splicing
SpliceAI	<0.2	all four deltas below 0.2 · G>T here scores Δ0.41 · evaluated, not missing
Constraint at this position
Conservation	phyloP 8.2	GERP 1.4, phastCons 1
Regional constraint	o/e 0.94	unconstrained · MANE · 32 kb · p 0.21 · regional, not allelic
Overall
CADD	29.4	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 0.000169% European (non-Finnish) · 2/1,180,016 alleles

Filtering AF 2.8e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 1.1e-05%

Overall 0.000137% 2/1,461,850 alleles · very rare

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.Arg101Gly
Coding: c.301C>G
MANE Select: NM_000022
dbSNP: rs121908717
Type: single nucleotide variant
Location: chr20:44626517 (GRCh38)
Gene constraint: LOEUF 1.184 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 96.81 · 2 PDB
Residue 101: a UniProt-annotated variant site (in adascid); a UniProt-annotated variant site (in adascid; loss of activity); a β-strand

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.Arg101Gln Pathogenic ★★ same residue
ADA p.Arg101Leu Pathogenic/Likely pathogenic ★★ same residue
ADA p.Arg101Trp Pathogenic/Likely pathogenic ★★ same residue
ADA p.Arg101= 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

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-arg101gly (accessed [today's date]).

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