Is SDHA p.Phe33Ser (c.98T>C) pathogenic?

SDHA p.Phe33Ser (c.98T>C) is classified Uncertain significance in SDHA (ClinVar, Single submitter, 1 submitter; last evaluated 2019-05-14). AlphaMissense: ambiguous (0.4997); Absent from gnomAD v4.1; Associated with mitochondrial complex II deficiency, nuclear type 1.

What condition is associated with SDHA p.Phe33Ser (c.98T>C)?

SDHA p.Phe33Ser (c.98T>C) is associated with mitochondrial complex II deficiency, nuclear type 1, pheochromocytoma/paraganglioma syndrome 5 (ClinVar).

How common is SDHA p.Phe33Ser (c.98T>C) in the general population?

SDHA p.Phe33Ser (c.98T>C) is absent from gnomAD v4.1 (gnomAD).

How is Isolated succinate-CoQ reductase deficiency inherited?

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

What do computational predictors say about SDHA p.Phe33Ser (c.98T>C)?

AlphaMissense predicts ambiguous (score 0.4997) — an in-silico prediction, not a clinical call.

SDHA p.Phe33Ser

c.98T>C · rs1734831975 · VCV947040

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

ambiguous

0.4997 · ACMG-weighted

gnomAD v4.1

Absent

absent from gnomAD v4.1

Conditions

mitochondrial complex II deficiency, nuclear type 1

Computational evidence

Protein change
AlphaMissense	0.4997	ambiguous
REVEL	0.348	indeterminate
SaProt	LLR -5.48	tolerated
Splicing
SpliceAI	<0.2	no splice effect predicted · four deltas, not one · how we know
Constraint at this position
Conservation	phyloP 7.8	GERP 1.8, phastCons 1
Regional constraint	o/e 0.76	unconstrained · MANE · 38 kb · p 1.1e-12 · regional, not allelic
Overall
CADD	23.1	PHRED · no single calibrated threshold — expert panels disagree

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

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: SDHA
Protein: p.Phe33Ser
Coding: c.98T>C
MANE Select: NM_004168
dbSNP: rs1734831975
Type: single nucleotide variant
Location: chr5:223516 (GRCh38)
Gene constraint: LOEUF 0.786 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 94.06 · 5 PDB
Residue 33: a UniProt-annotated variant site (in)

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

Disease context

mitochondrial complex II deficiency, nuclear type 1 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

Also linked: pheochromocytoma/paraganglioma syndrome 5

For Isolated succinate-CoQ reductase deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy, Neonatal

Similar variants

SDHA p.Phe33Leu Uncertain significance ★ ⚠ same residue
SDHA p.Phe33fs Pathogenic ★ same residue
SDHA c.1064+1G>A Likely pathogenic ★★ same condition
SDHA c.1064+1G>T Likely pathogenic ★★ same condition
SDHA c.1064+2T>A Likely pathogenic ★★ same condition
SDHA c.1065-2A>G Likely pathogenic ★★ same condition
SDHA c.1260+1G>T Likely pathogenic ★★ same condition
SDHA c.1260+2T>A 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/sdha-p-phe33ser (accessed [today's date]).

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