Is SDHA p.Ala591= (c.1773G>T) pathogenic?

SDHA p.Ala591= (c.1773G>T) is classified Likely benign in SDHA (ClinVar, Multiple submitters, 2 submitters; last evaluated 2025-08-09). Very rare (popmax 0.00133%, afr); Associated with mitochondrial complex II deficiency, nuclear type 1.

What condition is associated with SDHA p.Ala591= (c.1773G>T)?

SDHA p.Ala591= (c.1773G>T) is associated with mitochondrial complex II deficiency, nuclear type 1, pheochromocytoma/paraganglioma syndrome 5, hereditary neoplastic syndrome (ClinVar).

How common is SDHA p.Ala591= (c.1773G>T) in the general population?

SDHA p.Ala591= (c.1773G>T) is very rare (popmax 0.00133%, afr) (gnomAD).

How is Isolated succinate-CoQ reductase deficiency inherited?

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

SDHA p.Ala591=

c.1773G>T · rs555028212 · VCV1779840

Likely benign Multiple submitters

Classification

Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 2 submitters

gnomAD v4.1

Rare

very rare (popmax 0.00133%, afr)

Conditions

mitochondrial complex II deficiency, nuclear type 1

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	<0.2	no splice effect predicted · four deltas, not one · how we know
Constraint at this position
Conservation	phyloP -1.4	GERP -3.1, phastCons 0.001
Overall
CADD	0.29	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00133% African / African-American · 1/74,922 alleles

Overall 6.2e-05% 1/1,613,866 alleles · very rare exomes 0/1,461,640 · genomes 1/152,226 · joint denominator

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: SDHA
Protein: p.Ala591=
Coding: c.1773G>T
MANE Select: NM_004168
dbSNP: rs555028212
Type: single nucleotide variant
Location: chr5:251447 (GRCh38)
Gene constraint: LOEUF 0.786 · pLI <0.01 (gnomAD)
Structure: AlphaFold pLDDT 94.06 · 5 PDB

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 hereditary neoplastic syndrome

For Isolated succinate-CoQ reductase deficiency (Orphanet):

Inheritance: Autosomal recessive
Onset: Infancy, Neonatal

Similar variants

SDHA p.Ala591Thr Uncertain significance ★★ ⚠ same residue
SDHA p.Ala591Val Uncertain significance ★★ ⚠ 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-ala591 (accessed [today's date]).

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