Is PIGN p.Ser135= (c.405C>T) pathogenic?

PIGN p.Ser135= (c.405C>T) is classified Likely benign in PIGN (ClinVar, Single submitter, 1 submitter; last evaluated 2022-09-01). Very rare (popmax 0.00267%, afr); Associated with multiple congenital anomalies-hypotonia-seizures syndrome 1.

What condition is associated with PIGN p.Ser135= (c.405C>T)?

PIGN p.Ser135= (c.405C>T) is associated with multiple congenital anomalies-hypotonia-seizures syndrome 1 (ClinVar).

How common is PIGN p.Ser135= (c.405C>T) in the general population?

PIGN p.Ser135= (c.405C>T) is very rare (popmax 0.00267%, afr) (gnomAD).

PIGN p.Ser135=

c.405C>T · rs1250542028 · VCV1146706

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

very rare (popmax 0.00267%, afr)

Conditions

multiple congenital anomalies-hypotonia-seizures syndrome 1

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 4.2	GERP 0.31, phastCons 1
Overall
CADD	9.686	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00267% African / African-American · 2/74,814 alleles

Filtering AF 0.000444% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000166%

Overall 0.000186% 3/1,609,054 alleles · very rare exomes 2/1,456,940 · genomes 1/152,114 · joint denominator

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.00267%	37,407
Admixed American	0.00167%	59,758

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: PIGN
Protein: p.Ser135=
Coding: c.405C>T
MANE Select: NM_176787
dbSNP: rs1250542028
Type: single nucleotide variant
Location: chr18:62157166 (GRCh38)
Gene constraint: LOEUF 1.46 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 88.33

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

Disease context

multiple congenital anomalies-hypotonia-seizures syndrome 1 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Similar variants

PIGN p.Ser135Asn Uncertain significance ★ ⚠ same residue
PIGN c.1251+1G>A Pathogenic/Likely pathogenic ★★ same condition
PIGN c.1252-2A>G Pathogenic/Likely pathogenic ★★ same condition
PIGN c.1434+5G>A Pathogenic/Likely pathogenic ★★ same condition
PIGN c.1574+1G>A Likely pathogenic ★★ same condition
PIGN c.1674+1G>A Likely pathogenic ★★ same condition
PIGN c.1674+1G>C Pathogenic ★★ same condition
PIGN c.1675-1G>T 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/pign-p-ser135 (accessed [today's date]).

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