Is MTTP p.Asn780= (c.2340T>C) pathogenic?

MTTP p.Asn780= (c.2340T>C) is classified Likely benign in MTTP (ClinVar, Single submitter, 2 submitters; last evaluated 2025-10-04). Very rare (popmax 0.0022%, sas); Associated with abetalipoproteinemia.

What condition is associated with MTTP p.Asn780= (c.2340T>C)?

MTTP p.Asn780= (c.2340T>C) is associated with abetalipoproteinemia (ClinVar).

How common is MTTP p.Asn780= (c.2340T>C) in the general population?

MTTP p.Asn780= (c.2340T>C) is very rare (popmax 0.0022%, sas) (gnomAD).

How is Abetalipoproteinemia inherited?

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

MTTP p.Asn780=

c.2340T>C · rs1578257346 · VCV796184

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 2 submitters

gnomAD v4.1

Rare

very rare (popmax 0.0022%, sas)

Conditions

abetalipoproteinemia

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 0.021	GERP -2.9, phastCons 0.87
Overall
CADD	6.962	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0022% South Asian · 2/91,052 alleles

Filtering AF 0.000365% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.000137%

Overall 0.000137% 2/1,460,712 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: MTTP
Protein: p.Asn780=
Coding: c.2340T>C
MANE Select: NM_001386140
dbSNP: rs1578257346
Type: single nucleotide variant
Location: chr4:99619096 (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 780: a UniProt-annotated variant site (in abl; no loss on localization to the endoplasmic reticulum; does not reduce interaction with p4hb/pdi; inhibits phospholipid or triglyceride transfer activity; inhibits apolipoprotein b secretion)

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.Asn780Tyr Pathogenic 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-asn780 (accessed [today's date]).

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