Is CBS p.Pro78Arg (c.233C>G) pathogenic?

CBS p.Pro78Arg (c.233C>G) is classified Uncertain significance in CBS (ClinVar, Multiple submitters, 4 submitters; last evaluated 2023-03-15). AlphaMissense: likely benign (0.1383); Absent from gnomAD v4.1; Associated with familial thoracic aortic aneurysm and aortic dissection.

How common is CBS p.Pro78Arg (c.233C>G) in the general population?

CBS p.Pro78Arg (c.233C>G) is absent from gnomAD v4.1 (gnomAD).

What do computational predictors say about CBS p.Pro78Arg (c.233C>G)?

AlphaMissense predicts likely benign (score 0.1383) — an in-silico prediction, not a clinical call.

CBS p.Pro78Arg

Q: What condition is associated with CBS p.Pro78Arg (c.233C>G)?

CBS p.Pro78Arg (c.233C>G) is associated with familial thoracic aortic aneurysm and aortic dissection, classic homocystinuria (ClinVar).

Q: How is Familial thoracic aortic aneurysm and aortic dissection inherited?

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

c.233C>G · rs786204608 · VCV188988

Uncertain significance Multiple submitters

Classification

Uncertain significance

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 4 submitters

AlphaMissense

likely benign

0.1383 · ACMG-weighted

gnomAD v4.1

Not reported

no allele count reported in gnomAD v4.1 (AN 406,478)

Missense predictors

2/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

familial thoracic aortic aneurysm and aortic dissection

Computational evidence

Protein change
AlphaMissense	0.1383	likely benign
REVEL	0.946	strongly pathogenic-leaning
SaProt	LLR -12.29	damaging
⇒ REVEL and SaProt call this damaging; AlphaMissense does not.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 9.5	GERP 1.4, phastCons 1
Regional constraint	o/e 0.63	unconstrained · MANE · 5,845 bp · p 0.12 · regional, not allelic
Overall
CADD	27.1	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

No allele count reported in gnomAD v4.1 (AN 406,478). This is missing data, not an absence: the variant may or may not be present in gnomAD. Rarity (ACMG PM2) and BA1/BS1 cannot be assessed for it.

Variant & gene context

Gene: CBS
Protein: p.Pro78Arg
Coding: c.233C>G
MANE Select: NM_000071
dbSNP: rs786204608
Type: single nucleotide variant
Location: chr21:43068592 (GRCh38)
Structure: AlphaFold pLDDT 90.15 · 28 PDB
Residue 78: a β-strand; a UniProt-annotated variant site (in cbsd; severe form; associated in cis with n-102; decreased cystathionine beta-synthase activity; decreased homotetramer formation)

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

Disease context

familial thoracic aortic aneurysm and aortic dissection — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: classic homocystinuria

For Familial thoracic aortic aneurysm and aortic dissection (Orphanet):

Inheritance: Autosomal dominant
Onset: Adolescent, Adult, Childhood

Similar variants

CBS p.Pro78= Likely benign ★ same residue
CBS c.1145+1G>A Pathogenic/Likely pathogenic ★★ same condition
CBS c.1223+1G>T Pathogenic ★★ same condition
CBS c.1224-2A>C Pathogenic ★★ same condition
CBS c.1358+1G>A Pathogenic ★★ same condition
CBS c.1359-1G>C Pathogenic/Likely pathogenic ★★ same condition
CBS c.1468-1G>A Likely pathogenic ★★ same condition
CBS c.1552+1G>A Pathogenic/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/cbs-p-pro78arg (accessed [today's date]).

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