Is MPL p.Ser550= (c.1650C>T) pathogenic?

MPL p.Ser550= (c.1650C>T) is classified Likely benign in MPL (ClinVar, Single submitter, 2 submitters; last evaluated 2025-12-11). Ultra-rare (popmax 0.02%, afr); Associated with congenital amegakaryocytic thrombocytopenia.

What condition is associated with MPL p.Ser550= (c.1650C>T)?

MPL p.Ser550= (c.1650C>T) is associated with congenital amegakaryocytic thrombocytopenia, essential thrombocythemia (ClinVar).

How common is MPL p.Ser550= (c.1650C>T) in the general population?

MPL p.Ser550= (c.1650C>T) is ultra-rare (popmax 0.02%, afr) (gnomAD).

MPL p.Ser550=

c.1650C>T · rs377715574 · VCV698496

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 2 submitters

gnomAD v4.1

Rare

ultra-rare (popmax 0.02%, afr)

Conditions

congenital amegakaryocytic thrombocytopenia

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 1.2	GERP 0.53, phastCons 1
Overall
CADD	5.835	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.02% African / African-American · 15/74,876 alleles

Filtering AF 0.0123% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.0099%

Overall 0.00105% 17/1,613,494 alleles · ultra-rare exomes 6/1,461,380 · genomes 11/152,114 · joint denominator

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.02%	4,992
Remaining individualsnot grpmax-eligible	0.0032%	31,239

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: MPL
Protein: p.Ser550=
Coding: c.1650C>T
MANE Select: NM_005373
dbSNP: rs377715574
Type: single nucleotide variant
Location: chr1:43352300 (GRCh38)
Gene constraint: LOEUF 1.022 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 73.44 · 1 PDB

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

Disease context

congenital amegakaryocytic thrombocytopenia — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: essential thrombocythemia

Similar variants

MPL p.Ser550Asn Uncertain significance ★ ⚠ same residue
MPL c.1165+1G>C Likely pathogenic ★★ same condition
MPL c.1166-1G>C Likely pathogenic ★★ same condition
MPL c.1468+2T>C Pathogenic/Likely pathogenic ★★ same condition
MPL c.1469-2A>T Pathogenic/Likely pathogenic ★★ same condition
MPL c.1566-1G>A Likely pathogenic ★★ same condition
MPL c.1653+1G>C Likely pathogenic ★★ same condition
MPL c.79+2T>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/mpl-p-ser550 (accessed [today's date]).

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