Barth syndrome is an ultra-rare X-linked recessive mitochondrial disorder caused by hemizygous pathogenic variants in TAFAZZIN, which encodes the cardiolipin remodeling enzyme tafazzin. Defective tafazzin activity increases monolysocardiolipin, decreases mature cardiolipin, and destabilizes mitochondrial membrane structure, oxidative phosphorylation, and metabolic flexibility in high-energy tissues. The core phenotype includes cardiomyopathy, left ventricular noncompaction, neutropenia, skeletal myopathy, exercise intolerance, growth delay, recurrent bacterial infections, and 3-methylglutaconic aciduria, with lactic acidosis and arrhythmia risk in a subset of affected boys.
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name: Barth syndrome
creation_date: '2026-04-12T00:00:00Z'
updated_date: '2026-05-21T04:58:02Z'
category: Mendelian
synonyms:
- BTHS
- TAFAZZIN-related Barth syndrome
description: >-
Barth syndrome is an ultra-rare X-linked recessive mitochondrial disorder
caused by hemizygous pathogenic variants in TAFAZZIN, which encodes the
cardiolipin remodeling enzyme tafazzin. Defective tafazzin activity increases
monolysocardiolipin, decreases mature cardiolipin, and destabilizes
mitochondrial membrane structure, oxidative phosphorylation, and metabolic
flexibility in high-energy tissues. The core phenotype includes
cardiomyopathy, left ventricular noncompaction, neutropenia, skeletal
myopathy, exercise intolerance, growth delay, recurrent bacterial infections,
and 3-methylglutaconic aciduria, with lactic acidosis and arrhythmia risk in a
subset of affected boys.
disease_term:
preferred_term: Barth syndrome
term:
id: MONDO:0010543
label: Barth syndrome
classifications:
harrisons_chapter:
- classification_value: GENETICS_ENVIRONMENT_DISEASE
- classification_value: CARDIOVASCULAR
mechanistic_category:
- classification_value: mitochondrial disease
parents: []
prevalence:
- notes: >-
Ultra-rare. Published review literature in 2019 described fewer than 200
reported cases worldwide, while emphasizing likely underdiagnosis.
evidence:
- reference: PMID:31239752
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Although Barth syndrome is still an orphan disease, with fewer than 200
cases described so far, there is extensive ongoing research with regard to
its pathomechanism and new therapeutic approaches.
explanation: >-
This review directly supports that Barth syndrome is ultra-rare and had
fewer than 200 described cases at the time of publication.
inheritance:
- name: X-linked recessive
inheritance_term:
preferred_term: X-linked recessive inheritance
term:
id: HP:0001419
label: X-linked recessive inheritance
description: >-
Barth syndrome is inherited in an X-linked recessive manner and primarily
affects hemizygous males, while heterozygous females are typically
asymptomatic carriers.
evidence:
- reference: PMID:31239752
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Objectives: Barth syndrome is an ultra-rare, infantile-onset, X-linked
recessive mitochondrial disorder, primarily affecting males, due to
variants in TAZ encoding for the cardiolipin transacylase tafazzin.
explanation: >-
The review abstract explicitly identifies Barth syndrome as an X-linked
recessive disorder affecting males.
genetic:
- name: TAFAZZIN
gene_term:
preferred_term: TAFAZZIN
term:
id: hgnc:11577
label: TAFAZZIN
association: Loss-of-function
presence: Positive
features: >-
Hemizygous pathogenic variants in TAFAZZIN disrupt tafazzin-mediated
cardiolipin remodeling. Reported disease alleles include missense, nonsense,
frameshift, splice-site, and larger rearrangement variants, with substantial
inter-individual phenotypic variability and no robust genotype-phenotype
correlation.
evidence:
- reference: PMID:23409742
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
It is caused by mutations in the TAZ gene encoding tafazzin, a protein
involved in the metabolism of cardiolipin, a mitochondrial-specific
phospholipid involved in mitochondrial energy production.
explanation: >-
This clinical series directly identifies TAZ/TAFAZZIN mutation as the
molecular cause of Barth syndrome.
- reference: CGGV:assertion_1629e6ab-9749-4949-bf54-fe1addf4dcfd-2021-02-12T170000.000Z
reference_title: "TAFAZZIN / Barth syndrome (Definitive)"
supports: SUPPORT
evidence_source: OTHER
snippet: "TAFAZZIN | HGNC:11577 | Barth syndrome | MONDO:0010543 | XL | Definitive"
explanation: ClinGen classifies the TAFAZZIN-Barth syndrome gene-disease relationship as definitive with X-linked inheritance.
pathophysiology:
- name: Tafazzin deficiency impairs cardiolipin remodeling
description: >-
Loss of tafazzin activity disrupts remodeling of mitochondrial cardiolipin,
producing the signature increase in monolysocardiolipin and reduction in
mature cardiolipin. Because cardiolipin is essential for inner-membrane
architecture and energy transduction, this lipid-remodeling defect is the
initiating lesion for downstream mitochondrial dysfunction in Barth syndrome.
genes:
- preferred_term: TAFAZZIN
term:
id: hgnc:11577
label: TAFAZZIN
cell_types:
- preferred_term: cardiomyocyte
term:
id: CL:0000746
label: cardiac muscle cell
biological_processes:
- preferred_term: cardiolipin metabolic process
term:
id: GO:0032048
label: cardiolipin metabolic process
modifier: DYSREGULATED
evidence:
- reference: PMID:23409742
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
It is caused by mutations in the TAZ gene encoding tafazzin, a protein
involved in the metabolism of cardiolipin, a mitochondrial-specific
phospholipid involved in mitochondrial energy production.
explanation: >-
This directly links TAFAZZIN mutation to defective cardiolipin metabolism,
the primary molecular lesion in Barth syndrome.
downstream:
- target: Increased monolysocardiolipin:cardiolipin ratio
description: Defective tafazzin-mediated cardiolipin remodeling produces the diagnostic increase in the MLCL:CL ratio.
causal_link_type: DIRECT
evidence:
- reference: PMID:18070816
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All BTHS patients (n = 31) had monolysocardiolipin:cardiolipin ratios
>0.40 and all controls (n = 215) had monolysocardiolipin:cardiolipin
ratios <0.23.
explanation: >-
Patient bloodspot data support increased MLCL:CL ratio as the direct
biochemical consequence of tafazzin-dependent cardiolipin remodeling
failure.
- target: Elevated urinary 3-methylglutaconic acid
description: >-
The tafazzin defect is associated with 3-methylglutaconic aciduria,
although the intermediate metabolic route is not fully resolved.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:23409742
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
BACKGROUND: Barth syndrome (BS) is an X-linked infantile-onset
cardioskeletal disease characterized by cardiomyopathy, hypotonia, growth
delay, neutropenia and 3-methylglutaconic aciduria. It is caused by
mutations in the TAZ gene encoding tafazzin, a protein involved in the
metabolism of cardiolipin, a mitochondrial-specific phospholipid involved
in mitochondrial energy production.
explanation: >-
The clinical series links TAZ/tafazzin mutations with
3-methylglutaconic aciduria, while the omitted intermediate mechanism is
left explicit as unknown.
- target: Growth delay
description: >-
Tafazzin-related multisystem mitochondrial disease includes constitutional
growth delay through incompletely resolved energetic, feeding, and systemic
intermediates.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:23409742
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
BACKGROUND: Barth syndrome (BS) is an X-linked infantile-onset
cardioskeletal disease characterized by cardiomyopathy, hypotonia, growth
delay, neutropenia and 3-methylglutaconic aciduria. It is caused by
mutations in the TAZ gene encoding tafazzin, a protein involved in the
metabolism of cardiolipin, a mitochondrial-specific phospholipid involved
in mitochondrial energy production.
explanation: >-
The clinical series supports growth delay as part of tafazzin-related
Barth syndrome, but does not define the full growth-delay mechanism.
- target: Left ventricular noncompaction
description: >-
Tafazzin-related cardiac disease can include left ventricular
noncompaction; the developmental intermediates between cardiolipin
remodeling failure and noncompaction morphology remain incompletely
resolved.
causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
evidence:
- reference: PMID:23361305
supports: PARTIAL
evidence_source: HUMAN_CLINICAL
snippet: >-
In both brothers, 2D-echocardiography revealed some features of left
ventricular noncompaction (LVNC) despite marked differences in the course
of the disease;
explanation: >-
Affected siblings with TAZ mutation showed LVNC features, supporting the
branch while leaving the developmental mechanism unspecified.
- target: Mitochondrial respiratory chain dysfunction
causal_link_type: DIRECT
- target: Myocardial metabolic substrate shift
causal_link_type: DIRECT
- target: Impaired myeloid maturation
description: >-
Tafazzin/cardiolipin defects can impair myeloid output through
mitochondrial membrane-potential loss and apoptosis in myeloid progenitors.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- Mitochondrial membrane-potential dissipation in myeloid progenitor cells
- Cytochrome c release and caspase-3 activation
evidence:
- reference: PMID:30451719
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
TAZ knockdown experiments suggest accelerated apoptosis of myeloid
progenitor cells due to increased dissipation of mitochondrial membrane
potential, aberrant release of cytochrome c and activation of caspase-3.
explanation: >-
Tafazzin knockdown experiments provide a mechanistic bridge from the
primary cardiolipin-remodeling defect to impaired granulopoiesis.
- name: Mitochondrial respiratory chain dysfunction
description: >-
Cardiolipin deficiency destabilizes the mitochondrial inner membrane,
lowering membrane potential and impairing respiratory chain function. In
patient-derived cells and affected tissues, this is accompanied by abnormal
reactive oxygen species handling and reduced ATP-generating capacity.
biological_processes:
- preferred_term: oxidative phosphorylation
term:
id: GO:0006119
label: oxidative phosphorylation
modifier: DECREASED
evidence:
- reference: PMID:23361305
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
An examination of the patients' fibroblast cultures revealed that
extremely low mitochondrial membrane potentials (mtΔΨ about 50 % of the
control value) dominated other unspecific mitochondrial changes detected
(respiratory chain dysfunction, abnormal ROS production and depressed
antioxidant defense).
explanation: >-
Patient-derived fibroblasts demonstrate markedly impaired membrane
potential together with respiratory chain dysfunction, supporting a core
mitochondrial bioenergetic defect.
downstream:
- target: Myocardial metabolic substrate shift
causal_link_type: DIRECT
- target: Abnormal cardiomyocyte calcium handling
causal_link_type: DIRECT
- target: Skeletal muscle mitochondrial myopathy
description: >-
Respiratory-chain and membrane-potential impairment in skeletal muscle
produces the mitochondrial myopathy branch of Barth syndrome.
causal_link_type: DIRECT
evidence:
- reference: PMID:23361305
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Our studies confirm generalised mitochondrial dysfunction in the
skeletal muscle and the fibroblasts of BTHS patients, especially a severe
impairment in the mitochondrial membrane potential and the inhibition of
complex V activity.
explanation: >-
Patient skeletal-muscle studies directly support a mitochondrial
myopathy branch downstream of respiratory-chain dysfunction.
- name: Myocardial metabolic substrate shift
description: >-
Tafazzin-deficient cardiomyocytes show reduced mitochondrial fatty-acid
utilization and compensatory reliance on glucose and alternative anaplerotic
fuels. This metabolic rewiring reflects impaired mitochondrial substrate
handling and contributes to contractile inefficiency in the Barth heart.
cell_types:
- preferred_term: cardiomyocyte
term:
id: CL:0000746
label: cardiac muscle cell
biological_processes:
- preferred_term: fatty acid beta-oxidation
term:
id: GO:0006635
label: fatty acid beta-oxidation
modifier: DECREASED
evidence:
- reference: PMID:31861102
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
We also demonstrate that TAZ517delG induces metabolic alterations in
pathways related to energy production as reflected by high glucose uptake,
an increase in glycolytic lactate production and a decrease in palmitate
uptake.
explanation: >-
Patient-derived and genome-edited iPSC cardiomyocytes show a shift away
from fatty-acid use toward glucose-reliant metabolism.
- reference: PMID:37930434
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
In mice with an inducible knockdown (KD) of TAFAZZIN,
explanation: >-
The abstract explicitly identifies an inducible Tafazzin-knockdown mouse
model as one of the systems used to demonstrate the reported metabolic
rewiring in Barth syndrome.
- reference: PMID:37930434
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
in induced pluripotent stem cell-derived cardiac myocytes, mitochondrial
uptake and oxidation of fatty acids was strongly decreased, while glucose
uptake was increased.
explanation: >-
iPSC-derived cardiac myocytes independently show decreased mitochondrial
fatty-acid utilization with compensatory glucose uptake.
downstream:
- target: Abnormal cardiomyocyte calcium handling
causal_link_type: DIRECT
- target: Lactic acidosis
description: >-
The glucose-shifted energy phenotype increases glycolytic lactate
production, providing a cellular correlate for lactic acidosis in Barth
syndrome.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
evidence:
- reference: PMID:31861102
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
We also demonstrate that TAZ517delG induces metabolic alterations in
pathways related to energy production as reflected by high glucose
uptake, an increase in glycolytic lactate production and a decrease in
palmitate uptake.
explanation: >-
Barth iPSC-cardiomyocytes show glycolytic lactate overproduction as part
of the metabolic rewiring downstream of tafazzin deficiency.
- name: Abnormal cardiomyocyte calcium handling
description: >-
In Barth syndrome cardiomyocytes, excess mitochondrial and cellular reactive
oxygen species activates the CaMKII-RYR2 axis, increasing sarcoplasmic
reticulum calcium leak. The result is abnormal diastolic calcium handling,
reduced calcium transient amplitude, impaired contractility, and greater
arrhythmia vulnerability.
cell_types:
- preferred_term: cardiomyocyte
term:
id: CL:0000746
label: cardiac muscle cell
biological_processes:
- preferred_term: cardiac muscle contraction
term:
id: GO:0060048
label: cardiac muscle contraction
modifier: DECREASED
evidence:
- reference: PMID:33793303
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Compared with wild-type controls, BTHS-induced pluripotent stem
cell-derived cardiomyocytes had increased diastolic Ca2+ and decreased
Ca2+ transient amplitude.
explanation: >-
This directly demonstrates abnormal calcium homeostasis in
Barth-syndrome iPSC-derived cardiomyocytes.
- reference: PMID:33793303
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Inhibition of this reactive oxygen species-CaMKII-RYR2 pathway through
pharmacological inhibitors or genome editing normalized aberrant Ca2+
handling in BTHS-induced pluripotent stem cell-derived cardiomyocytes and
improved their contractile function.
explanation: >-
Rescue of calcium handling and contractility identifies ROS-CaMKII-RYR2
signaling as a causal mechanism rather than a bystander abnormality.
downstream:
- target: Cardiomyopathy
description: >-
Abnormal calcium handling reduces cardiomyocyte contractility, linking the
mitochondrial ROS-CaMKII-RYR2 axis to Barth cardiomyopathy.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- Reduced calcium transient amplitude
- Decreased cardiomyocyte contractility
evidence:
- reference: PMID:33793303
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
Inhibition of this reactive oxygen species-CaMKII-RYR2 pathway through
pharmacological inhibitors or genome editing normalized aberrant Ca2+
handling in BTHS-induced pluripotent stem cell-derived cardiomyocytes and
improved their contractile function.
explanation: >-
Rescue of calcium handling improves contractility in Barth iPSC-derived
cardiomyocytes, supporting the calcium-handling-to-contractile-disease
link.
- target: Arrhythmia
description: >-
Calcium leak and abnormal calcium cycling increase arrhythmia
vulnerability in tafazzin-deficient cardiac models.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- ROS-CaMKII-RYR2 activation
- Sarcoplasmic-reticulum calcium leak
evidence:
- reference: PMID:33793303
supports: SUPPORT
evidence_source: MODEL_ORGANISM
snippet: >-
A subset of mice with cardiac-specific TAZ inactivation developed
arrhythmias, including bidirectional ventricular tachycardia, atrial
tachycardia, and complete atrioventricular block.
explanation: >-
The cardiac-specific Tafazzin knockout mouse model links tafazzin
deficiency and abnormal calcium signaling to arrhythmia vulnerability.
- name: Skeletal muscle mitochondrial myopathy
description: >-
Tafazzin deficiency causes skeletal-muscle mitochondrial dysfunction,
reducing muscle oxygen extraction and producing the proximal myopathy and
severe exercise limitation typical of Barth syndrome.
cell_types:
- preferred_term: skeletal muscle cell
term:
id: CL:0000188
label: cell of skeletal muscle
biological_processes:
- preferred_term: oxidative phosphorylation
term:
id: GO:0006119
label: oxidative phosphorylation
modifier: DECREASED
- preferred_term: muscle contraction
term:
id: GO:0006936
label: muscle contraction
modifier: DECREASED
evidence:
- reference: PMID:23361305
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Our studies confirm generalised mitochondrial dysfunction in the skeletal
muscle and the fibroblasts of BTHS patients, especially a severe
impairment in the mitochondrial membrane potential and the inhibition of
complex V activity.
explanation: >-
Patient skeletal-muscle testing directly supports mitochondrial myopathy
as a Barth syndrome mechanism.
- reference: PMID:21873497
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In conclusion, severe exercise intolerance in BTHS is due to both cardiac
and skeletal muscle impairments that are consistent with cardiac and
skeletal mitochondrial myopathy.
explanation: >-
Exercise physiology in affected patients links the skeletal mitochondrial
myopathy branch to severe exercise limitation.
downstream:
- target: Proximal muscle weakness
description: Skeletal mitochondrial myopathy manifests clinically as proximal muscle weakness.
causal_link_type: DIRECT
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Skeletal myopathy predominantly affects the proximal muscles, and
results in delays in development of early motor skills.
explanation: >-
GeneReviews links Barth skeletal myopathy to proximal muscle
involvement.
- target: Exercise intolerance
description: Combined skeletal-muscle and cardiac mitochondrial impairment produces severe exercise limitation.
causal_link_type: DIRECT
evidence:
- reference: PMID:21873497
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In conclusion, severe exercise intolerance in BTHS is due to both
cardiac and skeletal muscle impairments that are consistent with cardiac
and skeletal mitochondrial myopathy.
explanation: >-
Patient exercise testing directly attributes severe exercise
intolerance to skeletal and cardiac mitochondrial myopathy.
- name: Impaired myeloid maturation
description: >-
Barth-syndrome neutropenia reflects impaired granulocytic maturation rather
than a pure peripheral destruction phenotype. Bone-marrow studies show
reduced maturation of the myeloid lineage, providing a mechanistic basis for
intermittent or chronic neutropenia and recurrent infection risk.
cell_types:
- preferred_term: neutrophil
term:
id: CL:0000775
label: neutrophil
biological_processes:
- preferred_term: myeloid cell differentiation
term:
id: GO:0030099
label: myeloid cell differentiation
modifier: DECREASED
evidence:
- reference: PMID:30451719
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Pretreatment bone marrow evaluations predominantly showed reduced myeloid
maturation which normalized on G-CSF therapy in seven of 13 examined.
explanation: >-
Bone-marrow findings in affected patients support impaired myeloid
maturation as a direct mechanism of Barth-syndrome neutropenia.
- reference: PMID:30451719
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
TAZ knockdown experiments suggest accelerated apoptosis of myeloid
progenitor cells due to increased dissipation of mitochondrial membrane
potential, aberrant release of cytochrome c and activation of caspase-3.
explanation: >-
Tafazzin knockdown experiments support mitochondrial progenitor-cell
apoptosis as a mechanistic contributor to the myeloid maturation defect.
downstream:
- target: Neutropenia
description: Reduced myeloid maturation limits mature neutrophil output.
causal_link_type: DIRECT
evidence:
- reference: PMID:30451719
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Decreased myeloid maturation was reported for five of six patients prior
to G-CSF therapy. The common abnormality was a relative paucity of mature
neutrophils in the marrow.
explanation: >-
Patient bone-marrow findings link reduced myeloid maturation to paucity
of mature neutrophils.
- target: Recurrent bacterial infections
description: Impaired granulopoiesis and neutropenia increase bacterial infection risk.
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
intermediate_mechanisms:
- Decreased mature neutrophil output
- Chronic or intermittent neutropenia
evidence:
- reference: PMID:30451719
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Consistent clinical improvement, with reduced signs and symptoms of
infections, was observed in response to prophylactic G-CSF
explanation: >-
Clinical improvement of infections after neutrophil-directed therapy
supports the maturation/neutropenia-to-infection branch.
phenotypes:
- name: Cardiomyopathy
description: >-
Cardiomyopathy is the central clinical manifestation of Barth syndrome and
may be dilated, hypertrophic, or mixed with endocardial fibroelastosis or
noncompaction features.
phenotype_term:
preferred_term: Cardiomyopathy
term:
id: HP:0001638
label: Cardiomyopathy
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Cardiomyopathy, which is almost always present before age five years, is
typically dilated cardiomyopathy with or without endocardial
fibroelastosis or left ventricular noncompaction; hypertrophic
cardiomyopathy can also occur.
explanation: >-
GeneReviews summarizes cardiomyopathy as the dominant early-life Barth
syndrome phenotype and defines its major structural subtypes.
- name: Left ventricular noncompaction
description: >-
Prominent ventricular trabeculation and noncompaction morphology are common
cardiac features and may be present even when overall disease severity
differs between affected individuals.
phenotype_term:
preferred_term: Left ventricular noncompaction cardiomyopathy
term:
id: HP:0011664
label: Left ventricular noncompaction cardiomyopathy
evidence:
- reference: PMID:23361305
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In both brothers, 2D-echocardiography revealed some features of left
ventricular noncompaction (LVNC) despite marked differences in the course
of the disease;
explanation: >-
This affected-sibling report directly documents LVNC as a Barth syndrome
cardiac phenotype.
- name: Arrhythmia
description: >-
Cardiac arrhythmias, including ventricular tachyarrhythmia risk, are part of
the Barth cardiac phenotype and contribute to sudden-death risk.
phenotype_term:
preferred_term: Arrhythmia
term:
id: HP:0011675
label: Arrhythmia
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Heart failure is a significant cause of morbidity and mortality; risk of
arrhythmia and sudden death is increased.
explanation: >-
GeneReviews identifies increased arrhythmia and sudden-death risk in Barth
syndrome.
- name: Neutropenia
description: >-
Neutropenia may be chronic, intermittent, or cyclic, and contributes
substantially to infection risk and aphthous ulceration.
phenotype_term:
preferred_term: Neutropenia
term:
id: HP:0001875
label: Decreased total neutrophil count
evidence:
- reference: PMID:30451719
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Major features include neutropenia, dilated cardiomyopathy, motor delay
and proximal myopathy, feeding problems, and constitutional growth delay.
explanation: >-
This large Barth syndrome neutropenia review identifies neutropenia as one
of the defining disease manifestations.
sequelae:
- target: Recurrent bacterial infections
description: Neutropenia increases susceptibility to bacterial infections including pneumonia and sepsis.
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Neutropenia is most often associated with bacterial infections and
aphthous ulcers, pneumonia, and sepsis.
explanation: >-
GeneReviews directly links Barth syndrome neutropenia to bacterial
infection sequelae.
- name: Growth delay
description: >-
Constitutional growth impairment begins in childhood and is a common
component of the multisystem phenotype.
phenotype_term:
preferred_term: Growth delay
term:
id: HP:0001510
label: Growth delay
evidence:
- reference: PMID:23409742
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
BACKGROUND: Barth syndrome (BS) is an X-linked infantile-onset
cardioskeletal disease characterized by cardiomyopathy, hypotonia, growth
delay, neutropenia and 3-methylglutaconic aciduria.
explanation: >-
This clinical series explicitly lists growth delay among the core Barth
syndrome manifestations.
- name: Proximal muscle weakness
description: >-
Skeletal myopathy predominantly involves proximal musculature and contributes
to motor delay and reduced physical performance.
phenotype_term:
preferred_term: Proximal muscle weakness
term:
id: HP:0003701
label: Proximal muscle weakness
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Skeletal myopathy predominantly affects the proximal muscles, and results
in delays in development of early motor skills.
explanation: >-
GeneReviews directly supports proximal-predominant skeletal muscle
involvement in Barth syndrome.
- name: Exercise intolerance
description: >-
Profound exercise limitation reflects the combined effect of impaired cardiac
reserve and reduced skeletal-muscle oxygen extraction/utilization.
phenotype_term:
preferred_term: Exercise intolerance
term:
id: HP:0003546
label: Exercise intolerance
evidence:
- reference: PMID:21873497
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
In conclusion, severe exercise intolerance in BTHS is due to both cardiac
and skeletal muscle impairments that are consistent with cardiac and
skeletal mitochondrial myopathy.
explanation: >-
This exercise-physiology study directly attributes exercise intolerance to
combined cardiac and skeletal-muscle dysfunction in Barth syndrome.
- name: Recurrent bacterial infections
description: >-
Recurrent bacterial infection is a major downstream consequence of Barth
syndrome neutropenia and includes pneumonia, sepsis, cellulitis, and oral
ulcer-associated infection.
phenotype_term:
preferred_term: Recurrent bacterial infections
term:
id: HP:0002718
label: Recurrent bacterial infections
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Neutropenia is most often associated with bacterial infections and
aphthous ulcers, pneumonia, and sepsis.
explanation: >-
GeneReviews links Barth syndrome neutropenia to recurrent bacterial
infectious complications.
biochemical:
- name: Increased monolysocardiolipin:cardiolipin ratio
presence: INCREASED
notes: >-
The MLCL:CL ratio is the key biochemical signature of Barth syndrome and is
sufficiently robust for dried-blood-spot screening.
evidence:
- reference: PMID:18070816
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All BTHS patients (n = 31) had monolysocardiolipin:cardiolipin ratios
>0.40 and all controls (n = 215) had monolysocardiolipin:cardiolipin
ratios <0.23.
explanation: >-
This bloodspot assay study establishes an increased MLCL:CL ratio as the
defining Barth syndrome biomarker.
readouts:
- target: Tafazzin deficiency impairs cardiolipin remodeling
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: An increased monolysocardiolipin:cardiolipin ratio directly reports the tafazzin-dependent cardiolipin remodeling defect.
evidence:
- reference: PMID:18070816
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All BTHS patients (n = 31) had monolysocardiolipin:cardiolipin ratios
>0.40 and all controls (n = 215) had monolysocardiolipin:cardiolipin
ratios <0.23.
explanation: >-
Patient bloodspot data support the MLCL:CL ratio as a diagnostic
biochemical readout of the cardiolipin remodeling defect.
- name: Elevated urinary 3-methylglutaconic acid
presence: INCREASED
biomarker_term:
preferred_term: 3-methylglutaconic acid
term:
id: CHEBI:144330
label: 3-methylglutaconic acid
notes: >-
Increased urinary 3-methylglutaconic acid is a classic metabolic marker,
although it may be absent in some neonatal presentations.
evidence:
- reference: PMID:23409742
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All patients exhibited 3-methylglutaconic aciduria and neutropenia, when
tested and five of them also had lactic acidosis.
explanation: >-
This case series directly documents 3-methylglutaconic aciduria as a
common biochemical abnormality in Barth syndrome.
readouts:
- target: Tafazzin deficiency impairs cardiolipin remodeling
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: Urinary 3-methylglutaconic acid elevation is a classic metabolic readout associated with the tafazzin/cardiolipin-remodeling defect, although the intermediate route is unresolved.
evidence:
- reference: PMID:23409742
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
BACKGROUND: Barth syndrome (BS) is an X-linked infantile-onset
cardioskeletal disease characterized by cardiomyopathy, hypotonia, growth
delay, neutropenia and 3-methylglutaconic aciduria. It is caused by
mutations in the TAZ gene encoding tafazzin, a protein involved in the
metabolism of cardiolipin, a mitochondrial-specific phospholipid involved
in mitochondrial energy production.
explanation: >-
The clinical series links Barth syndrome 3-methylglutaconic aciduria to
TAZ/tafazzin and cardiolipin metabolism, supporting the diagnostic
readout link while leaving intermediate mechanisms unresolved.
- name: Lactic acidosis
presence: INCREASED
biomarker_term:
preferred_term: lactate
term:
id: CHEBI:24996
label: lactate
notes: >-
Lactic acidosis accompanies the mitochondrial energy defect in a substantial
subset of affected patients and may be particularly prominent in severe
infantile presentations.
evidence:
- reference: PMID:23409742
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
All patients exhibited 3-methylglutaconic aciduria and neutropenia, when
tested and five of them also had lactic acidosis.
explanation: >-
This cohort directly reports lactic acidosis in most evaluated patients.
readouts:
- target: Myocardial metabolic substrate shift
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: Increased lactate reports the glucose-shifted, glycolytic component of Barth mitochondrial energy rewiring.
evidence:
- reference: PMID:31861102
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
We also demonstrate that TAZ517delG induces metabolic alterations in
pathways related to energy production as reflected by high glucose
uptake, an increase in glycolytic lactate production and a decrease in
palmitate uptake.
explanation: >-
Barth iPSC-cardiomyocytes show increased glycolytic lactate production
as part of the metabolic substrate shift, supporting lactate as a
readout of that mechanism.
- reference: PMID:23409742
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
CONCLUSIONS: Lactic acidosis associated with 3-methylglutaconic aciduria
is highly suggestive of BS, whilst the severity of the metabolic
decompensation at disease onset should be considered for prognostic
purposes.
explanation: >-
The clinical series supports lactic acidosis in diagnostic and
decompensation contexts, complementing the cellular lactate-production
mechanism.
- target: Mitochondrial respiratory chain dysfunction
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: Lactic acidosis also reports the upstream mitochondrial respiratory dysfunction branch of Barth syndrome.
evidence:
- reference: PMID:23361305
supports: SUPPORT
evidence_source: IN_VITRO
snippet: >-
An examination of the patients' fibroblast cultures revealed that
extremely low mitochondrial membrane potentials (mtΔΨ about 50 % of the
control value) dominated other unspecific mitochondrial changes detected
(respiratory chain dysfunction, abnormal ROS production and depressed
antioxidant defense).
explanation: >-
Patient-derived fibroblast cultures show mitochondrial membrane-potential
loss with respiratory-chain dysfunction, supporting the upstream
mitochondrial dysfunction target.
- reference: PMID:23361305
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Severe lactic acidosis without 3-methylglutaconic aciduria in male
neonates as well as asymptomatic left ventricular noncompaction at ECHO
record may characterise a range of natural history of Barth syndrome.
explanation: >-
The affected-sibling report documents severe neonatal lactic acidosis as
part of the Barth syndrome clinical spectrum, supporting lactate as the
clinical readout paired with the mitochondrial dysfunction evidence.
treatments:
- name: Heart failure pharmacotherapy
description: >-
Standard heart-failure medications are used to manage Barth cardiomyopathy,
with careful attention to volume status because affected patients are
vulnerable to overdiuresis and dehydration.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
for heart failure, careful fluid and volume management and avoidance of
overdiuresis and dehydration, standard heart failure medications, and
cardiac transplantation when heart failure is severe and intractable.
explanation: >-
GeneReviews supports standard heart-failure pharmacotherapy as core
management for Barth cardiomyopathy.
target_phenotypes:
- preferred_term: Cardiomyopathy
term:
id: HP:0001638
label: Cardiomyopathy
target_mechanisms:
- target: Mitochondrial respiratory chain dysfunction
treatment_effect: MODULATES
description: >-
Standard heart-failure pharmacotherapy (ACE inhibitors, beta-blockers,
diuretics) reduces cardiac afterload and sympathetic drive, lowering
myocardial energy demand and alleviating the hemodynamic stress imposed
by mitochondrial respiratory chain dysfunction in Barth cardiomyocytes.
- name: Granulocyte colony-stimulating factor (G-CSF)
description: >-
G-CSF is used prophylactically in neutropenic Barth syndrome patients to
reduce severe bacterial infection risk and improve marrow neutrophil
maturation.
treatment_term:
preferred_term: hematopoietic growth factor therapy
term:
id: NCIT:C15262
label: Immunotherapy
evidence:
- reference: PMID:30451719
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Prophylaxis with G-CSF ± antibiotics prevents serious bacterial infections
in the more severe neutropenic patients although infections remain a
threat even in patients who are very compliant with therapy, especially in
those with indwelling devices.
explanation: >-
This review directly supports G-CSF prophylaxis as effective management
for severe Barth-syndrome neutropenia.
target_phenotypes:
- preferred_term: Neutropenia
term:
id: HP:0001875
label: Decreased total neutrophil count
- preferred_term: Recurrent bacterial infections
term:
id: HP:0002718
label: Recurrent bacterial infections
target_mechanisms:
- target: Impaired myeloid maturation
treatment_effect: ACTIVATES
description: G-CSF promotes marrow myeloid differentiation and mature neutrophil output.
evidence:
- reference: PMID:30451719
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Pretreatment bone marrow evaluations predominantly showed reduced
myeloid maturation which normalized on G-CSF therapy in seven of 13
examined.
explanation: >-
Patient marrow examinations support G-CSF activation/restoration of
impaired myeloid maturation.
- name: Elamipretide
description: >-
Elamipretide is a cardiolipin-directed mitochondrial therapy used to improve
muscle strength in Barth syndrome.
treatment_term:
preferred_term: Pharmacotherapy
term:
id: NCIT:C15986
label: Pharmacotherapy
therapeutic_agent:
- preferred_term: elamipretide
term:
id: CHEBI:233331
label: elamipretide
evidence:
- reference: PMID:25299040
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: >-
Targeted therapy: Elamipretide is indicated for the improvement of muscle
strength in individuals with Barth syndrome.
explanation: >-
The updated GeneReviews management section identifies elamipretide as a
Barth syndrome-targeted therapy for muscle weakness.
target_phenotypes:
- preferred_term: Proximal muscle weakness
term:
id: HP:0003701
label: Proximal muscle weakness
target_mechanisms:
- target: Tafazzin deficiency impairs cardiolipin remodeling
treatment_effect: MODULATES
description: >-
Elamipretide is a cardiolipin-targeting tetrapeptide that associates
with cardiolipin on the inner mitochondrial membrane, stabilizing
cardiolipin-protein complexes and partially compensating for the
cardiolipin remodeling defect caused by tafazzin deficiency.
datasets: []
references:
- reference: PMID:25299040
title: "Barth Syndrome."
tags:
- GeneReviews
findings: []
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.