Is MTTP p.Gln441Ter (c.1321C>T) pathogenic?

MTTP p.Gln441Ter (c.1321C>T) is classified Likely pathogenic in MTTP (ClinVar, Single submitter, 1 submitter; last evaluated 2019-11-27). Absent from gnomAD v4.1; Associated with abetalipoproteinemia.

What condition is associated with MTTP p.Gln441Ter (c.1321C>T)?

MTTP p.Gln441Ter (c.1321C>T) is associated with abetalipoproteinemia (ClinVar).

How common is MTTP p.Gln441Ter (c.1321C>T) in the general population?

MTTP p.Gln441Ter (c.1321C>T) is absent from gnomAD v4.1 (gnomAD).

How is Abetalipoproteinemia inherited?

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

MTTP p.Gln441Ter

c.1321C>T · rs1486643983 · VCV983697

Likely pathogenic Single submitter

Classification

Likely pathogenic

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

Consequence

nonsense (stop-gain)

predicted LoF

gnomAD v4.1

Absent

absent from gnomAD v4.1

Conditions

abetalipoproteinemia

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation/SpliceAI carries the signal.
Consequence	nonsense (stop-gain)	predicted loss-of-function
NMD	predicted	premature termination codon in exon 10 of 18
Splicing
SpliceAI	Δ0.49	donor loss · deltas
Pangolin	Δ0.38	loss · gain 0.00 · agrees with SpliceAI · independent
Constraint at this position
Conservation	phyloP 3.3	GERP 0.94, phastCons 1
Overall
CADD	37.0	PHRED · no single calibrated threshold — expert panels disagree

Predicted loss-of-function is descriptive, not an applied PVS1 code.

Population frequency

gnomAD v4.1 · exomes + genomes

Absent from gnomAD v4.1. Not observed in any sequenced alleles — a rarity signal (ACMG PM2-supporting), not evidence of pathogenicity on its own.

Variant & gene context

Gene: MTTP
Protein: p.Gln441Ter
Coding: c.1321C>T
MANE Select: NM_001386140
dbSNP: rs1486643983
Type: single nucleotide variant
Location: chr4:99601691 (GRCh38)
Gene constraint: LOEUF 0.672 · pLI <0.01 · ClinGen HI gene assoc. with recessive phenotype (gnomAD)
Structure: AlphaFold pLDDT 86.73 · 2 PDB
Residue 441: the vitellogenin domain; a turn

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

Disease context

abetalipoproteinemia — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Abetalipoproteinemia (Orphanet):

Inheritance: Autosomal recessive
Onset: Childhood, Infancy
Prevalence: <1 / 1 000 000 (Worldwide)

Similar variants

MTTP p.Gln441Lys Uncertain significance ★ ⚠ same residue
MTTP c.1067+1G>C Likely pathogenic ★★ same condition
MTTP c.1769+2T>C Pathogenic/Likely pathogenic ★★ same condition
MTTP c.1867+1G>A Pathogenic ★★ same condition
MTTP c.1867+5G>A Pathogenic/Likely pathogenic ★★ same condition
MTTP c.1868-2A>G Likely pathogenic ★★ same condition
MTTP c.2342+1G>A Pathogenic ★★ same condition
MTTP c.502-1G>C 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/mttp-p-gln441ter (accessed [today's date]).

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