Arterial Tortuosity Syndrome

1. Disease Information

Overview

Arterial Tortuosity Syndrome is a rare, monogenic connective tissue disorder primarily affecting the vascular system. It was first described clinically approximately 55 years ago (Ertugrul, 1967) and its genetic basis was elucidated in 2006 when Coucke et al. identified mutations in SLC2A10 as the causative defect (PMID: 16550171). ATS is characterized by generalized tortuosity, elongation, and stenosis of large and medium-sized arteries, with a propensity for aneurysm formation. Patients also display connective tissue features overlapping with Ehlers-Danlos syndromes and Loeys-Dietz syndrome.

Key Identifiers

Synonyms and Alternative Names

• Arterial Tortuosity Syndrome (ATS)
• Tortuosity of systemic arteries
• Arterial tortuosity (MeSH)

Information Sources

Information is derived from aggregated disease-level resources (OMIM, Orphanet, GeneReviews) and individual case reports/series from published literature. The largest systematic cohort study encompasses 102 patients from 92 families (Beyens et al. 2018, PMID: 29323665). A 2025 longitudinal study (CLARITY) provides the most recent prospective cardiovascular data on 14 patients (PMID: 40613586).

2. Etiology

Disease Causal Factors

ATS is a monogenic (Mendelian) disorder caused by biallelic (homozygous or compound heterozygous) loss-of-function mutations in the SLC2A10 gene. There are no known environmental or infectious causes.

As stated in the original discovery paper: "Mutations in one of these genes, SLC2A10, encoding the facilitative glucose transporter GLUT10, were identified in six ATS families. GLUT10 deficiency is associated with upregulation of the TGFbeta pathway in the arterial wall" (PMID: 16550171).

Risk Factors

Genetic Risk Factors

• Biallelic pathogenic variants in SLC2A10: The sole known cause. Over 30 distinct pathogenic variants have been reported across different ethnic groups.
• Consanguinity: Significantly increases risk given autosomal recessive inheritance. Multiple reported families are consanguineous, particularly in Middle Eastern, North African, South Asian, and Mediterranean populations (PMID: 29323665; PMID: 37619836).
• Carrier status in parents: Both parents must be carriers (heterozygous) for affected offspring; 25% recurrence risk per pregnancy.

Environmental Risk Factors

• No environmental risk factors have been identified for ATS development. As a fully penetrant Mendelian disorder, the disease is determined by genotype.

Protective Factors

Genetic Protective Factors

• No specific modifier alleles or protective variants have been identified in humans.
• Notably, the ability of mice to endogenously synthesize ascorbic acid (via L-gulonolactone oxidase, encoded by Gulo) appears to protect Slc2a10 knockout mice from the full ATS phenotype. Humans lack functional GULO and cannot synthesize ascorbate, contributing to disease severity (PMID: 32307537).

Environmental Protective Factors

• No confirmed environmental protective factors. It has been hypothesized that adequate ascorbic acid intake may have modifying effects given the ascorbate compartmentalization hypothesis, but this has not been clinically validated.

Gene-Environment Interactions

The interplay between GLUT10 deficiency and the human inability to synthesize ascorbic acid represents a critical gene–environment (nutrient) interaction that likely determines disease severity. Mice with intact ascorbic acid synthesis via Gulo are protected from the full disease phenotype even when lacking GLUT10, while Gulo;Slc2a10 double knockout mice that cannot synthesize ascorbate show compromised ECM and mitochondrial defects: "Altogether, our data add evidence that ATS is an ascorbate compartmentalization disorder, but additional factors underlying the observed phenotype in humans remain to be determined" (PMID: 32307537).

3. Phenotypes

Cardiovascular Phenotypes

The CLARITY longitudinal study reported that "aortic root dilation was present in 71.4%; branch pulmonary artery (BPA) dimensions were mixed between dilated and hypoplastic" (PMID: 40613586). The largest cohort study documented: "Stenoses, tortuosity, and aneurysm formation are widespread occurrences. Severe but rare vascular complications include early and aggressive aortic root aneurysms, neonatal intracranial bleeding, ischemic stroke, and gastric perforation" (PMID: 29323665).

Connective Tissue Phenotypes

Respiratory Phenotypes

Other Rare Phenotypes

"A patient with microcephaly and a complex uropathy and two cases with diaphragmatic hernia are noticed." (PMID: 37619836)

Quality of Life Impact

ATS significantly impacts quality of life, particularly in childhood, due to: - Cardiovascular surveillance burden (repeated imaging, echocardiography) - Potential need for surgical interventions (pulmonary artery reconstruction, aortopexy) - Joint laxity affecting mobility and musculoskeletal function - Risk of cerebrovascular events limiting physical activity - Respiratory complications in the neonatal period - Psychosocial burden of a chronic rare disease

No formal QoL studies (EQ-5D, SF-36, PROMIS) specific to ATS have been published. This represents a significant gap in the literature.

4. Genetic/Molecular Information

Causal Gene

• Gene: SLC2A10 (Solute Carrier Family 2 Member 10)
• HGNC ID: HGNC:13445
• NCBI Gene ID: 81031
• OMIM Gene: *606145
• Chromosomal Location: 20q13.12
• Protein: GLUT10 (Facilitative Glucose Transporter Member 10), 541 amino acids, 12 predicted transmembrane domains
• UniProt: O95528

Pathogenic Variants

Variant Types Reported

ATS-causing variants span the full spectrum of loss-of-function mutations:

Additional frameshift and splice-site variants have been reported (see ClinVar entries for SLC2A10).

Variant Classification

• All disease-causing variants are classified as pathogenic or likely pathogenic per ACMG/AMP guidelines.
• The disorder shows strict genotype-phenotype correlation: biallelic loss-of-function variants are required for disease manifestation.

Allele Frequency

• Pathogenic variants in SLC2A10 are extremely rare or absent in population databases (gnomAD, 1000 Genomes).
• Some founder mutations are enriched in specific populations (e.g., p.Ser81Arg in Arab populations; PMID: 35302653).

Functional Consequences

All known pathogenic variants result in loss of function of GLUT10 through: - Premature protein truncation (nonsense, frameshift) - Misfolding or impaired membrane insertion (missense) - Loss of substrate transport activity - Re-expression of GLUT10 in patient fibroblasts rescues the cellular phenotype (PMID: 26376865)

All pathogenic variants are germline in origin. No somatic mutations have been reported.

Modifier Genes

No specific modifier genes have been identified in humans. However, the variable expressivity observed even among siblings with identical mutations suggests genetic modifiers or stochastic developmental factors influence disease severity. At the species level, GULO (L-gulonolactone oxidase) status serves as a major modifier — humans are pseudogene carriers (non-functional GULO), exacerbating GLUT10 deficiency effects compared to mice that retain functional Gulo (PMID: 32307537).

Epigenetic Information

No specific epigenetic modifications (DNA methylation, histone modifications, chromatin changes) have been described in ATS. Transcriptomic studies show dysregulation of genes involved in oxidative stress response and ECM homeostasis, but dedicated epigenomic profiling has not been performed.

Chromosomal Abnormalities

ATS is not caused by chromosomal abnormalities. No large-scale structural variants (aneuploidy, translocations, inversions) are associated with the disease. All causative mutations are point mutations or small indels within SLC2A10.

5. Environmental Information

Environmental Factors

ATS is a purely genetic disorder. No environmental toxins, radiation, pollution, or occupational exposures are known to cause or contribute to disease development.

Lifestyle Factors

While no lifestyle factors cause ATS, clinical management recommends: - Avoidance of contact sports and intense isometric exercise to reduce hemodynamic stress on weakened arterial walls - Blood pressure management to reduce risk of aneurysm progression - Adequate vitamin C intake may be theoretically important given the ascorbate compartmentalization hypothesis, but this remains clinically unvalidated

Infectious Agents

Not applicable. ATS is not caused or triggered by any infectious agent.

6. Mechanism / Pathophysiology

Overview: The Pathophysiological Cascade

The pathogenesis of ATS involves a multi-layered molecular cascade from the primary genetic defect to clinical manifestation:

SLC2A10 biallelic mutations
↓
GLUT10 protein loss-of-function
↓
Impaired dehydroascorbic acid (DAA) transport across endomembranes
↓
Reduced intracellular ascorbate in ER/mitochondria
↓
┌───────────────────┬────────────────────────┬──────────────────────┐
│                   │                        │                      │
▼                   ▼                        ▼                      ▼
Defective collagen  Impaired elastin     Oxidative stress     Mitochondrial
hydroxylation       assembly             (↑ ROS, ↑ lipid      dysfunction
(↓ prolyl/lysyl    (fragmented           peroxidation)        (compromised
hydroxylase         elastic fibers)      via altered PPARγ     respiration in
activity)                                                      VSMCs)
│                   │                        │                      │
└───────────────────┴────────────────────────┘                      │
    ↓                                               │
ECM disorganization                                         │
(↑ collagen deposition,                                     │
 ↓ elastic fiber integrity)                                 │
    ↓                                               │
Non-canonical TGF-β signaling  ←────────────────────────────┘
(αvβ3 integrin → p125FAK → p60Src → p38 MAPK)
    ↓
Vascular wall weakening
    ↓
Arterial tortuosity, elongation, stenosis, aneurysm

Molecular Pathways

TGF-β Signaling (GO:0007179)

The original discovery paper demonstrated "GLUT10 deficiency is associated with upregulation of the TGFbeta pathway in the arterial wall" (PMID: 16550171). However, subsequent work has significantly refined this understanding. In ATS fibroblasts, the primary TGF-β dysregulation occurs through a non-canonical pathway mediated by the αvβ3 integrin, involving p125FAK, p60Src, and p38 MAPK signaling, rather than the canonical SMAD2/3 pathway (PMID: 29587413; PMID: 26376865).

Importantly, histological analysis of end-stage skin and vascular tissue from ATS patients did not show increased canonical TGF-β signaling markers (pSMAD2/CTGF) (PMID: 29323665), and TGF-β signaling was unaltered in the Gulo;Slc2a10 double knockout mouse (PMID: 32307537). This suggests tissue-specific and temporal differences in TGF-β pathway involvement, and that canonical TGF-β upregulation may not be the primary driver of disease in all contexts.

Ascorbate Metabolism (GO:0019852)

GLUT10 has been confirmed as a DAA transporter: "The present results demonstrate that GLUT10 is a DAA transporter and DAA transport is diminished in the endomembranes of fibroblasts from ATS patients" (PMID: 27153185). Intracellular ascorbate is required as a cofactor for prolyl and lysyl hydroxylases that catalyze collagen cross-linking and for enzymes involved in elastin assembly. ATS has accordingly been characterized as an "ascorbate compartmentalization disorder" (PMID: 31621376; PMID: 32307537).

• CHEBI Terms: CHEBI:29073 (L-ascorbic acid), CHEBI:17242 (dehydroascorbic acid)

Oxidative Stress (GO:0006979)

Studies on ATS fibroblasts demonstrated "a marked increase in ROS-induced lipid peroxidation sustained by altered PPARγ function, which contributes to the redox imbalance and the compensatory antioxidant activity of ALDH1A1" (PMID: 26376865). The oxidative stress is a direct consequence of impaired intracellular ascorbate, which normally serves as a major intracellular antioxidant.

Integrin Signaling (GO:0007229)

In ATS fibroblasts, the αvβ3 integrin is preferentially recruited due to loss of the fibronectin-ECM and its canonical α5β1 integrin receptor. This integrin activates downstream signaling through p125FAK, p60Src, and p38 MAPK, contributing to ECM disarray and altered cell behavior (PMID: 29587413).

Cellular Processes

Extracellular Matrix Organization (GO:0030198)

Electron microscopy of ATS skin biopsies revealed: "Large spaces were observed among the collagen fibrils…suggesting disorganization of the collagen structures. Furthermore, elastin fiber contents and their thickness are reduced…In small muscular arteries in the skin from ATS patients, discontinuous internal elastic lamina, lack of myofilaments, and disorganized medial smooth muscle cells with vacuolated cytoplasm are present" (PMID: 35302653). The largest cohort study confirmed: "EM of skin EF shows a fragmented elastin core and a peripheral mantle of microfibrils of random directionality" (PMID: 29323665).

Mitochondrial Function (GO:0007005)

Zebrafish studies showed that "a large proportion of the genes, which were specifically dysregulated after glut10 depletion gene and not by tgfbr1 inhibition, play a major role in mitochondrial function" (PMID: 22116938). The Gulo;Slc2a10 double knockout mouse confirmed compromised mitochondrial respiration in smooth muscle cells (PMID: 32307537).

Protein Dysfunction

GLUT10 is a 541-amino acid transmembrane protein with 12 predicted transmembrane domains. In silico modeling identified potential substrate binding site residues including PRO531, GLU507, GLU437, and TRP432, with a highly recurrent point mutation (c.1309G>A, p.Glu437Lys) located directly in the predicted binding site region (PMID: 31203799).

Metabolic Changes

• Perturbation of pathways controlling cell energy balance (PMID: 26376865)
• Altered glucose metabolism (GLUT10 belongs to the glucose transporter family, though its primary in vivo substrate appears to be DAA)
• Impaired ascorbate-dependent hydroxylation reactions affecting collagen and elastin biosynthesis

Immune System Involvement

No primary immune dysfunction is described in ATS. Arterial wall inflammation may be secondary to ECM disruption and oxidative stress, but this has not been formally studied.

Tissue Damage Mechanisms

• Oxidative stress: ROS-induced lipid peroxidation damaging vascular wall
• Mechanical stress: Turbulent blood flow through tortuous vessels increases shear stress
• Elastic fiber fragmentation: Progressive weakening of arterial wall integrity
• Fibrosis: Compensatory collagen deposition with disorganized architecture

Biochemical Abnormalities

• Transporter dysfunction: Loss of GLUT10-mediated DAA transport across endomembranes
• Functional enzyme deficiency: Impaired intracellular ascorbate-dependent enzymes (prolyl 4-hydroxylase, lysyl hydroxylase) due to substrate compartmentalization failure (not systemic enzyme deficiency)

Molecular Profiling

• Transcriptomics: Gene expression profiling of ATS fibroblasts revealed dysregulation of genes involved in TGF-β signaling, ECM homeostasis, cell energy balance, and oxidative stress response (PMID: 26376865). Zebrafish transcriptome analysis showed high correlation between slc2a10 knockdown and tgfbr1 inhibition profiles, plus specific dysregulation of mitochondrial function genes (PMID: 22116938).
• Proteomics/Metabolomics/Lipidomics: No systematic studies have been published.
• Single-cell analysis, spatial transcriptomics, multi-omics: Not yet applied to ATS.
• Functional genomics screens: Not reported for ATS.

Key GO Terms for Biological Processes

• GO:0030198 — Extracellular matrix organization
• GO:0007179 — Transforming growth factor beta receptor signaling pathway
• GO:0006979 — Response to oxidative stress
• GO:0007229 — Integrin-mediated signaling pathway
• GO:0007005 — Mitochondrion organization
• GO:0019852 — L-ascorbic acid metabolic process
• GO:0071560 — Cellular response to transforming growth factor beta stimulus

Key Cell Types Involved

7. Anatomical Structures Affected

Organ Level

Primary Organs

Secondary Organ Involvement

Body systems involved: Cardiovascular (primary), musculoskeletal, integumentary, ocular, respiratory, gastrointestinal, nervous (secondary).

Tissue and Cell Level

• Arterial tunica media (UBERON:0002036): Elastic fibers fragmented, smooth muscle cells disorganized with vacuolated cytoplasm, discontinuous internal elastic lamina, lack of myofilaments (PMID: 35302653)
• Dermis: Collagen fibrils disorganized with large inter-fibrillar spaces; reduced elastin content and thickness
• Connective tissue (UBERON:0002384): Systemic ECM disorganization

Specific cell populations targeted: - Vascular smooth muscle cells (CL:0000359): Disorganized, vacuolated, lacking myofilaments - Fibroblasts (CL:0000057): Altered ECM production, oxidative stress - Endothelial cells (CL:0002543): Secondary to vascular wall disruption

Subcellular Level

• Endoplasmic reticulum (GO:0005783): Site of collagen hydroxylation requiring ascorbate; GLUT10 transports DHA across ER membranes
• Mitochondria (GO:0005739): Compromised respiration in GLUT10-deficient cells
• Extracellular matrix (GO:0031012): Fragmented elastic fibers, disorganized collagen
• Plasma membrane (GO:0005886): Altered integrin signaling (αvβ3 vs. α5β1)
• Endomembrane system (GO:0012505): Impaired DAA transport across endomembranes

Localization

• Bilateral and generalized: Arterial tortuosity affects arteries throughout the body symmetrically
• Predominantly supra-aortic involvement noted in some patients: "Regarding the vascular involvement, a predominant supra-aortic involvement stands out...All presented severe tortuosity of the intracranial arteries" (PMID: 37619836)
• Specific UBERON terms: UBERON:0000947 (aorta), UBERON:0002012 (pulmonary artery), UBERON:0001624 (carotid artery), UBERON:0001533 (subclavian artery), UBERON:0003496 (head blood vessel)

8. Temporal Development

Onset

• Typical age of onset: Congenital — arterial tortuosity is present from birth
• HPO: HP:0003577 (Congenital onset)
• Onset pattern: Congenital/chronic — the structural vascular defect is developmental, though clinical complications may present acutely
• Prenatal detection is possible via ultrasound as early as 22 weeks' gestation: "Prenatal ultrasound scanning at 29 weeks of gestation of the first fetus showed obvious tortuous and elongated of the aortic arch, ductus arteriosus, left and right pulmonary arteries" (PMID: 34384376)
• Clinical diagnosis typically occurs in infancy-early childhood (median diagnosis age 3.3 years per CLARITY study, PMID: 40613586)

Progression

• Disease course: Chronic, lifelong
• Progression rate: Variable; aortic dimensions increase with somatic growth but z-scores remain relatively stable
• Disease course pattern: Progressive structural changes superimposed on a chronic baseline
• Disease duration: Chronic lifelong; no remission

Critical period: The neonatal and infancy period (first 1-2 years of life) is the most critical for life-threatening events. As stated by Callewaert et al.: "Our data confirm that the cardiovascular prognosis in ATS is less severe than previously reported and that the first years of life are the most critical for possible life-threatening events" (PMID: 25373504).

Patterns

• No spontaneous remission: ATS does not remit
• Stability: After surviving infancy, many patients stabilize clinically. Some arterial stenoses may improve over time, though tortuosity is permanent.
• Connective tissue features (joint laxity, skin hyperextensibility) persist lifelong
• Keratoconus may progress during childhood/adolescence
• Risk of cerebrovascular events may extend into young adulthood (PMID: 34847858)

9. Inheritance and Population

Epidemiology

• Prevalence: Ultra-rare; estimated <1 per 1,000,000. Orphanet classifies prevalence as <1/1,000,000.
• As of 2023, only ~106 individuals with genetically confirmed ATS had been reported worldwide (PMID: 37619836).
• Incidence: Unknown; no population-based incidence data available.

Inheritance and Genetic Features

"Arterial tortuosity syndrome (ATS) is a rare congenital disorder characterized by elongation and tortuosity of the aorta and mid-sized arteries. Additional features typical of connective tissue disorders are usually present, but the clinical presentation of the syndrome can extensively change." (PMID: 39827853)

Founder Effects

The p.Ser81Arg (c.243C>G, rs80358230) variant appears to be a founder mutation in Arab populations. Faiyaz-Ul-Haque et al. studied 48 patients with this specific mutation from Arab families (PMID: 35302653; PMID: 36578839). Enrichment of ATS cases in populations with high rates of consanguinity (Middle Eastern, North African, South Asian, Mediterranean) is well documented.

Population Demographics

• Affected populations: Reported worldwide across diverse ethnic groups including Arab, Kurdish, Turkish, Italian, Macedonian, Indian, Japanese, Qatari, and European populations
• Geographic distribution: Global, but clusters in regions with higher consanguinity rates
• Sex ratio: Both sexes equally affected. In the CLARITY study, 64% were male (9/14), but the small sample size limits interpretation (PMID: 40613586).
• Age distribution: Diagnosis typically in infancy-early childhood; some patients now diagnosed prenatally

10. Diagnostics

Clinical Tests

Imaging Studies (Primary Diagnostic Modality)

• CT Angiography (CTA): Gold standard for demonstrating arterial tortuosity, elongation, stenosis, and aneurysm formation. Shows tortuosity of aorta, pulmonary arteries, carotid arteries, subclavian arteries, and intracranial vessels.
• Echocardiography: Essential for monitoring aortic root dimensions and pulmonary artery gradients. Serial measurements allow z-score tracking.
• MR Angiography (MRA): Non-ionizing alternative for vascular imaging, particularly useful in children and for intracranial vasculature.
• Prenatal ultrasound: Can detect arterial tortuosity as early as 22 weeks' gestation. "The key points of prenatal ultrasound diagnosis of ATS are the elongation and tortuosity of the large and medium sized arteries" (PMID: 34384376).

Laboratory Tests

• No specific blood biomarkers for ATS diagnosis or monitoring
• Routine metabolic panel typically normal
• No validated circulating biomarkers exist

Biopsy/Pathology Findings

Skin biopsy with electron microscopy shows disease-specific abnormalities: - Fragmented elastic fibers with fragmented elastin core - Peripheral mantle of microfibrils with random directionality - Disorganized collagen fibrils with increased inter-fibrillar spacing - In small muscular arteries: discontinuous internal elastic lamina, lack of myofilaments, disorganized medial smooth muscle cells with vacuolated cytoplasm (PMID: 35302653)

Genetic Testing

Recommended Approach

1. First-line: Targeted SLC2A10 gene sequencing when ATS is clinically suspected
2. Alternative: Connective tissue disorder / hereditary thoracic aortic disease (HTAD) gene panel including SLC2A10 alongside FBN1, TGFBR1/2, SMAD3, COL3A1, etc. (PMID: 39456956)
3. Whole exome sequencing (WES): Useful when clinical presentation is atypical or broader differential needed. "Whole exome sequencing (WES) was performed eight months after birth, two heterozygous variants of SLC2A10 gene was detected in newborn and their father and mother, respectively" (PMID: 34384376)
4. Whole genome sequencing (WGS): Also effective but not typically first-line
5. Prenatal genetic testing: Available for families with known mutations (CVS, amniocentesis)

CMA, karyotyping, FISH, mitochondrial DNA testing, and repeat expansion testing are not applicable to ATS diagnosis.

Clinical Criteria and Differential Diagnosis

No formal standardized diagnostic criteria (e.g., Ghent-like criteria) exist for ATS. Diagnosis is based on: 1. Clinical features: Generalized arterial tortuosity on imaging + connective tissue features 2. Genetic confirmation: Biallelic pathogenic variants in SLC2A10

Key differential diagnoses:

(PMID: 25821090; PMID: 29979900; PMID: 37692180)

Screening

• Newborn screening: Not included in standard newborn screening programs
• Carrier screening: Available for at-risk family members; "Notably, carrier testing for at-risk relatives is recommended to identify family members that may be affected by this condition" (PMID: 36578839)
• Cascade screening: Recommended for at-risk family members once an index case is identified
• Prenatal diagnosis: Possible via CVS or amniocentesis when familial mutations are known, and via detailed fetal echocardiography/ultrasound

11. Outcome / Prognosis

Survival and Mortality

• Earlier literature described ATS as having a high mortality rate due to major cardiovascular malformations
• More recent data demonstrate that the prognosis is less severe than previously reported: "Our data confirm that the cardiovascular prognosis in ATS is less severe than previously reported and that the first years of life are the most critical for possible life-threatening events" (PMID: 25373504)
• First years of life carry the highest risk of mortality from pulmonary artery stenosis, respiratory distress, intracranial hemorrhage, or aortic complications
• No unequivocal vascular dissections or ruptures have been documented, which is a critical distinguishing feature from vascular EDS and Loeys-Dietz syndrome (PMID: 29323665)
• No specific survival rate data (5-year, 10-year) are available due to disease rarity
• Many patients survive into adulthood; the oldest reported patients are in their 30s-40s (PMID: 34847858)

Morbidity and Function

• Chronic cardiovascular surveillance burden
• Potential need for surgical interventions: "Three patients underwent repeated BPA interventions, one patient had an aortopexy, and one patient had an aortic valve replacement. No patients had arterial dissections" (PMID: 40613586)
• Joint hypermobility may cause chronic musculoskeletal pain
• Visual impairment from keratoconus
• Risk of cerebrovascular events even in young adulthood

Complications

• Aortic root aneurysm (71.4% in CLARITY; may require valve/root replacement)
• Branch pulmonary artery stenosis (may require repeated catheter interventions or surgery)
• Ischemic stroke / transient ischemic attacks (rare but documented; PMID: 34847858)
• Neonatal intracranial hemorrhage (rare)
• Gastric perforation (rare)
• Infant respiratory distress syndrome
• Diaphragmatic hernia requiring surgical repair

Prognostic Factors

• Severity of neonatal presentation: IRDS, intracranial bleeding, severe PA stenosis carry worst prognosis
• Degree of pulmonary artery stenosis: Determines need for intervention and risk of RV failure
• Rate of aortic root dilation: Requires longitudinal z-score monitoring
• Access to specialized care: Early referral to high-specialized centers improves outcomes
• Specific mutation type: Genotype-phenotype correlations are poorly established due to small numbers

12. Treatment

Pharmacotherapy

Beta-Adrenergic Blockers (MAXO:0001298)

Beta-blockers (e.g., atenolol, propranolol) are first-line pharmacological treatment to reduce hemodynamic stress on arterial walls. "To reduce hemodynamic stress on the arterial wall, beta-adrenergic blocking treatment was prescribed" (PMID: 37619836). The rationale is extrapolated from management of Marfan syndrome and other aortopathies — reducing heart rate and blood pressure decreases shear stress on tortuous and dilated vessels.

Angiotensin Receptor Blockers (MAXO:0001299)

Losartan (angiotensin II type 1 receptor blocker) has been proposed based on its TGF-β antagonist properties and efficacy in Marfan syndrome mouse models: "In transgenic mouse models it was shown that losartan, an angiotensin II type 1 receptor with known inhibiting effects on TGFbeta, rescues the aortic phenotype" (PMID: 18630721). Clinical efficacy in ATS specifically is not yet established.

Antithrombotic Therapy

May be considered for secondary prevention of cerebrovascular events. One case report described treatment with recombinant tissue plasminogen activator (r-TPA) at 0.9 mg/kg for TIA with complete recovery (PMID: 34847858).

Pharmacogenomics

No pharmacogenomic data specific to ATS are available.

Surgical and Interventional (MAXO:0000004)

Pulmonary Artery Interventions

• Balloon angioplasty and stenting for pulmonary artery stenosis
• Total pulmonary arterial reconstruction for severe cases: "underwent a pulmonary arterial surgical reconstruction at the age of 2 years old due to the development of pulmonary artery stenosis" (PMID: 38987788)
• Surgical approaches may be preferred over transcatheter approaches, especially when peripheral arteries are involved
• Repeated interventions may be necessary

Aortic Surgery

• Aortopexy for symptomatic aortic tortuosity
• Aortic valve replacement when indicated
• Aortic root replacement for progressive aneurysmal dilation
• Coarctation repair when present

Diaphragmatic Hernia Repair

• Standard surgical repair when present (congenital diaphragmatic hernia)

Advanced Therapeutics

Gene Therapy (Future Potential)

• No gene therapy trials currently registered for ATS
• In vitro proof-of-concept: re-expression of GLUT10 in patient fibroblasts rescued the cellular phenotype, normalizing redox homeostasis and PPARγ activity (PMID: 26376865)
• Given the autosomal recessive loss-of-function mechanism, gene replacement therapy is conceptually feasible but has not been developed

Ascorbate Supplementation (Hypothetical)

• Based on the ascorbate compartmentalization hypothesis, high-dose ascorbate supplementation could theoretically be beneficial
• However, the defect is in intracellular transport rather than systemic ascorbate levels
• No clinical trials exist

Supportive and Rehabilitative (MAXO:0000502)

• Genetic counseling (MAXO:0000079): Essential for families regarding recurrence risk (25%) and carrier testing
• Multidisciplinary follow-up: Cardiology, ophthalmology, orthopedics, genetics, pulmonology
• Physical therapy: For joint hypermobility management
• Ophthalmologic monitoring: Regular eye examinations for keratoconus progression and management
• Cardiovascular surveillance (MAXO:0000127): Regular echocardiography and interval CTA/MRA

Treatment Strategy

Management requires a multidisciplinary approach (PMID: 37692180): - Close monitoring of aortic root early in life - Extensive vascular imaging afterwards - Surveillance and prevention are key - "Our findings warrant attention for IRDS and diaphragmatic hernia, close monitoring of the aortic root early in life, and extensive vascular imaging afterwards" (PMID: 29323665)

Relevant MAXO terms: - MAXO:0000502 — Counseling - MAXO:0000127 — Echocardiography - MAXO:0000004 — Surgical procedure - MAXO:0010033 — Medical management - MAXO:0001298 — Beta-adrenergic antagonist therapy - MAXO:0000079 — Genetic counseling

13. Prevention

Primary Prevention

As a Mendelian genetic disorder, primary prevention of disease occurrence is limited to: - Genetic counseling (MAXO:0000079) for consanguineous families and known carriers - Preimplantation genetic diagnosis (PGD) for families with known mutations - Prenatal genetic testing (CVS, amniocentesis) when familial mutations are established - Carrier screening in populations with known founder mutations (e.g., p.Ser81Arg in Arab populations)

Secondary Prevention (Early Detection)

• Prenatal ultrasound screening: Can detect arterial tortuosity as early as 22 weeks' gestation in at-risk pregnancies. "When ATS is suspected prenatally, the newborn should be referred immediately after birth to a high specialized center for proper neonatal care" (PMID: 39827853)
• Cascade genetic testing: For siblings and relatives of affected individuals
• Neonatal vigilance: Immediate referral to specialized center when ATS is suspected
• "In case of confirmed ATS, parents should be counseled regarding the recurrence risk in other pregnancies" (PMID: 39827853)

Tertiary Prevention (Preventing Complications)

• Regular cardiovascular surveillance (echocardiography, vascular imaging)
• Beta-blocker therapy to reduce hemodynamic stress
• Activity modification to avoid extreme physical exertion and contact sports
• Ophthalmologic monitoring for keratoconus progression
• Cerebrovascular risk management and antiplatelet prophylaxis when indicated

Immunization

Not applicable — ATS is not an infectious or immune-mediated disorder.

Behavioral Interventions

• Avoidance of isometric exercises and contact sports
• Blood pressure monitoring and management
• Regular medical follow-up compliance

Public Health

Given the ultra-rare nature of ATS (<1/1,000,000), population-level public health interventions are not practical. Awareness among pediatric cardiologists, geneticists, and prenatal sonographers is the most impactful public health measure.

14. Other Species / Natural Disease

Naturally Occurring Disease

No naturally occurring animal disease equivalent to human ATS has been reported in veterinary literature or in the OMIA database. This is likely because most animals (including mice, rats, dogs, cats) retain functional L-gulonolactone oxidase (Gulo) and can synthesize ascorbic acid endogenously, compensating for any GLUT10 dysfunction.

Orthologous Genes

Comparative Biology

The SLC2A10/GLUT10 gene is highly conserved across vertebrates, suggesting an essential role in development. A critical species difference is that mice (but not humans) can synthesize their own ascorbic acid via the gulonolactone oxidase (Gulo) pathway. This likely explains why simple Slc2a10 mutant mice fail to recapitulate the human vascular phenotype, while the Gulo;Slc2a10 double knockout (which eliminates both GLUT10 and endogenous ascorbate synthesis) shows a more informative phenotype (PMID: 32307537).

Guinea pigs and some primates share the human inability to synthesize ascorbic acid (non-functional GULO) and could theoretically manifest ATS-like phenotypes if SLC2A10 were disrupted, but no such models exist.

Transmission / Zoonotic Potential

Not applicable — ATS is a non-infectious genetic disorder with no zoonotic potential or cross-species transmission.

15. Model Organisms

Mouse Models

Slc2a10 Missense Models (G128E, S150F)

• Type: ENU-induced knock-in (missense substitutions)
• Phenotype recapitulation: None — "two mouse models, homozygous respectively for G128E and S150F missense substitutions in glut10 do not present any of the vascular, anatomical, or immunohistological abnormalities as encountered in human ATS patients" (PMID: 18693279)
• Limitation: Mice synthesize endogenous ascorbic acid via Gulo, compensating for GLUT10 deficiency
• NCBI Taxon: 10090

Gulo;Slc2a10 Double Knockout Model

• Type: Double gene knockout (Slc2a10 KO + Gulo KO — abolishes endogenous ascorbate synthesis)
• Phenotype recapitulation: Partial — "While Gulo;Slc2a10 double knock-out mice did not fully phenocopy human ATS, histological and immunocytochemical analysis revealed compromised extracellular matrix formation" and mitochondrial dysfunction in smooth muscle cells (PMID: 32307537)
• Key findings: TGF-β signaling unaltered; supports ascorbate compartmentalization hypothesis
• Significance: Strongest animal model evidence that ATS is fundamentally an ascorbate compartmentalization disorder
• Limitation: Does not fully phenocopy human vascular tortuosity, suggesting additional human-specific factors

Zebrafish Model

slc2a10 Morpholino Knockdown

• Type: Antisense morpholino oligonucleotide-mediated gene knockdown
• Phenotype recapitulation: Good — "knockdown of slc2a10 using antisense morpholino oligonucleotide injection caused a wavy notochord and cardiovascular abnormalities with a reduced heart rate and blood flow" (PMID: 22116938)
• Key findings: Cardiovascular phenotype partially phenocopied by TGF-β receptor (tgfbr1/alk5) small-molecule inhibitor; transcriptomic analysis revealed specific dysregulation of mitochondrial function genes distinct from tgfbr1 inhibition
• NCBI Taxon: 7955
• Limitation: Morpholino effects are transient; long-term vascular remodeling cannot be studied; zebrafish vascular anatomy differs significantly from human

Cell-Based Models

Patient-Derived Dermal Fibroblasts

• Type: Primary skin fibroblasts from ATS patients
• Applications: Most extensively used in vitro model
• Key findings:
• Demonstrated oxidative stress with ROS-induced lipid peroxidation and altered PPARγ function (PMID: 26376865)
• Confirmed impaired DAA transport across endomembranes (PMID: 27153185)
• Revealed non-canonical TGF-β signaling via αvβ3 integrin (PMID: 29587413)
• GLUT10 re-expression normalizes phenotype (proof of concept for gene therapy)
• Limitation: In vitro system; does not capture in vivo hemodynamic forces, developmental context, or cell-cell interactions

Model Summary

Key Gap

No single model fully recapitulates the severe human vascular phenotype of ATS. This suggests that additional human-specific factors — including the obligate dependence on dietary ascorbate, hemodynamic forces during human cardiovascular development, and perhaps differences in elastic fiber assembly — contribute to disease manifestation.

Mechanistic Model / Interpretation

Integrated Mechanistic Framework

Synthesizing all available evidence, ATS is best understood as an ascorbate compartmentalization disorder with multi-pathway downstream consequences:

1. Primary defect (upstream): Biallelic loss of GLUT10 → loss of DAA transport across endomembranes
2. Proximal consequences: Intracellular ascorbate deficiency in ER and mitochondria
3. Intermediate pathology (4 parallel arms):
4. ECM arm: Impaired prolyl/lysyl hydroxylase activity → defective collagen hydroxylation → fragmented elastic fibers + disorganized collagen
5. Redox arm: Loss of intracellular antioxidant → ROS accumulation → lipid peroxidation → altered PPARγ function
6. Mitochondrial arm: Ascorbate deficiency in mitochondria → compromised electron transport chain → impaired VSMC energy metabolism
7. Signaling arm: ECM disarray + fibronectin loss → αvβ3 integrin recruitment → non-canonical TGF-β signaling via FAK/Src/p38 MAPK
8. Convergent pathology (downstream): Vascular wall weakening → arterial tortuosity, elongation, stenosis, and aneurysm formation
9. Human amplification factor: Unlike most mammals, humans cannot synthesize ascorbate (non-functional GULO), making them uniquely vulnerable to GLUT10 deficiency

The canonical TGF-β/SMAD pathway, while highlighted in the original discovery paper, appears to be a secondary or context-dependent phenomenon rather than the primary driver. This is supported by: (a) absence of pSMAD2/CTGF upregulation in patient tissues, (b) unaltered TGF-β signaling in the Gulo;Slc2a10 double knockout mouse, and (c) non-canonical rather than canonical pathway activation in patient fibroblasts.

Evidence Base

Landmark Papers

Supporting Clinical Literature

Limitations and Knowledge Gaps

1. Ultra-rare disease with limited natural history data: With only ~106 confirmed patients, long-term outcomes, genotype-phenotype correlations, and rare complications may be underestimated or incompletely characterized.

2. No adequate animal model: No single animal model fully recapitulates human ATS. Mouse models are limited by endogenous ascorbate synthesis, and zebrafish models are limited by developmental and anatomical differences.

3. Pathomechanism incompletely understood: The relative contributions of ascorbate compartmentalization, TGF-β signaling (canonical vs. non-canonical), oxidative stress, and mitochondrial dysfunction remain unclear. The observation that end-stage tissue shows no canonical TGF-β upregulation creates an apparent contradiction with the original discovery that needs resolution.

4. No validated biomarkers: No circulating biomarkers exist for disease monitoring, progression prediction, or treatment response assessment.

5. No formal diagnostic criteria: Unlike Marfan syndrome (Ghent criteria) or EDS (2017 criteria), ATS lacks standardized clinical diagnostic criteria.

6. Treatment evidence is anecdotal: No clinical trials have been conducted for any intervention. Beta-blocker and losartan use is extrapolated from other aortopathies. The potential role of ascorbate supplementation is speculative.

7. No quality-of-life studies: Formal patient-reported outcome measures (EQ-5D, SF-36, PROMIS) have not been applied to ATS cohorts.

8. Omics data are sparse: No large-scale transcriptomic, proteomic, metabolomic, or epigenomic profiling of ATS patient tissues has been published. Single-cell approaches have not been applied.

9. Genotype-phenotype correlation poorly defined: While variable expressivity is well documented, specific relationships between mutation type/position and disease severity have not been systematically analyzed.

10. Prenatal natural history: Few cases have been diagnosed prenatally, limiting understanding of fetal disease progression and optimal prenatal management strategies.

Proposed Follow-up Experiments / Actions

Short-Term (1-3 years)

1. International ATS Registry: Establish a prospective, multicenter registry to systematically collect phenotypic, genotypic, treatment, and outcome data across all known patients, building on the CLARITY initiative framework.

2. Genotype-Phenotype Correlation Study: Using registry data, analyze whether specific mutation types (truncating vs. missense), positions within SLC2A10, or zygosity status (homozygous vs. compound heterozygous) predict disease severity, complication rates, or specific phenotypic features.

3. Circulating Biomarker Discovery: Profile serum/plasma from ATS patients using targeted proteomics and metabolomics to identify potential biomarkers for disease activity (e.g., ECM turnover markers such as desmosine/isodesmosine for elastin degradation, oxidative stress markers such as 8-isoprostane, TGF-β pathway markers).

4. Patient-Derived iPSC Vascular Models: Generate iPSC lines from ATS patients, differentiate into vascular smooth muscle cells and endothelial cells, and use these to study vascular pathomechanisms and screen potential therapeutics in a human-relevant system.

Medium-Term (3-5 years)

1. Improved Mouse Model: Generate a conditional Slc2a10 knockout on a Gulo-null background with vascular-specific and temporally controlled deletion, combined with controlled dietary ascorbate restriction, to better model human ATS.

2. Ascorbate Supplementation Pilot Study: Design a controlled clinical study evaluating high-dose ascorbic acid supplementation in ATS patients, monitoring aortic root dimensions, arterial stiffness, vascular tortuosity indices, and circulating biomarkers as endpoints.

3. Single-Cell RNA Sequencing: Perform scRNA-seq on ATS patient skin biopsies and available vascular tissue to identify cell-type-specific transcriptional signatures, prioritize therapeutic targets, and understand the cellular heterogeneity of disease.

4. TGF-β Pathway Dissection: Use patient-derived fibroblasts and iPSC-derived vascular cells to systematically dissect canonical vs. non-canonical TGF-β signaling across different cell types and developmental stages, resolving the apparent contradiction between in vitro and in vivo findings.

Long-Term (5+ years)

1. Gene Therapy Development: Explore AAV-mediated SLC2A10 gene replacement in vascular smooth muscle cells, first validating in the improved mouse model, then progressing toward clinical translation. The in vitro proof-of-concept (GLUT10 re-expression rescuing fibroblast phenotype) is encouraging.

2. Clinical Treatment Trial: Based on biomarker and mechanistic data, design a randomized controlled trial of pharmacological intervention (losartan, high-dose ascorbate, or novel targeted therapy) in ATS patients, leveraging the international registry for recruitment.

3. Formal Diagnostic Criteria Development: Convene an international expert panel to establish standardized diagnostic criteria for ATS, analogous to Ghent criteria for Marfan syndrome, incorporating clinical, imaging, and genetic features.

Report generated: 2026-05-05 | Based on analysis of 39 published studies and structured database resources | MONDO:0009005 | OMIM #208050