Is MOCOS p.Ser18= (c.54C>T) pathogenic?

MOCOS p.Ser18= (c.54C>T) is classified Likely benign in MOCOS (ClinVar, Single submitter, 1 submitter; last evaluated 2021-07-13). No allele count reported in gnomAD v4.1 (AN 1,248,420); Associated with xanthinuria type II.

What condition is associated with MOCOS p.Ser18= (c.54C>T)?

MOCOS p.Ser18= (c.54C>T) is associated with xanthinuria type II (ClinVar).

How common is MOCOS p.Ser18= (c.54C>T) in the general population?

MOCOS p.Ser18= (c.54C>T) is no allele count reported in gnomAD v4.1 (AN 1,248,420) (gnomAD).

How is Hereditary xanthinuria inherited?

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

MOCOS p.Ser18=

c.54C>T · rs2144887356 · VCV1571443

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Not reported

no allele count reported in gnomAD v4.1 (AN 1,248,420)

Conditions

xanthinuria type II

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -0.31	GERP -0.72
Overall
CADD	8.458	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

No allele count reported in gnomAD v4.1 (AN 1,248,420). 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: MOCOS
Protein: p.Ser18=
Coding: c.54C>T
MANE Select: NM_017947
dbSNP: rs2144887356
Type: single nucleotide variant
Location: chr18:36187593 (GRCh38)
Gene constraint: LOEUF 1.19 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 80.88

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

Disease context

xanthinuria type II — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Hereditary xanthinuria (Orphanet):

Inheritance: Autosomal recessive
Onset: All ages

Similar variants

MOS p.Ser18Leu Uncertain significance ★ ⚠ same residue
MOCOS c.1218+1G>C Likely pathogenic ★★ same condition
MOCOS c.2164+2T>C Likely pathogenic ★★ same condition
MOCOS c.232+1G>A Likely pathogenic ★★ same condition
MOCOS p.Arg419Ter Pathogenic ★★ same condition
MOCOS p.Arg776Cys Pathogenic/Likely pathogenic ★★ same condition
MOCOS p.Gln516Ter Likely pathogenic ★★ same condition
MOCOS p.Glu42Ter 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/mocos-p-ser18 (accessed [today's date]).

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