Sjögren-Larsson Syndrome (SLS): Comprehensive Research Report

1. Disease Information

Overview: Sjögren-Larsson syndrome (SLS) is a rare autosomal recessive neurocutaneous inborn error of lipid metabolism caused by deficiency of fatty aldehyde dehydrogenase (FALDH), encoded by ALDH3A2. It is defined by a classic clinical triad — congenital ichthyosis, spastic diplegia/tetraplegia, and intellectual disability — with a pathognomonic ophthalmologic finding (glistening white retinal dots/juvenile macular dystrophy) and characteristic leukoencephalopathy. First described by Sjögren and Larsson in Swedish patients (1956–1957).

Key identifiers: - OMIM: #270200 (phenotype); gene ALDH3A2 OMIM *609523 (HGNC:403, chromosome 17p11.2) - Orphanet: ORPHA:816 - MONDO: MONDO:0010031; Disease Ontology: DOID:14501 - ICD-10: Q87.1 (congenital malformation syndromes predominantly associated with short stature); ICD-11: 5C52.03 - MeSH: Sjogren-Larsson Syndrome

Source of information: This report draws on aggregated disease-level resources (OMIM, Orphanet, GeneReviews-type reviews, MedLink Neurology) and primary literature (case series, natural history cohorts from the Netherlands and Sweden, and single/multi-patient case reports) rather than raw individual EHR data.

Synonyms: SLS; Fatty aldehyde dehydrogenase deficiency; FALDH deficiency; Ichthyosis–spastic diplegia–oligophrenia syndrome.

2. Etiology

Causal factor: SLS is monogenic — biallelic loss-of-function variants in ALDH3A2 cause deficiency of FALDH (also called fatty alcohol:NAD+ oxidoreductase, FAO), leading to accumulation of long-chain fatty aldehydes and fatty alcohols (Rizzo, PMID: 16996289).

Genetic risk factors: - Homozygous or compound heterozygous ALDH3A2 variants are both necessary and sufficient — no modifier genes with established effect have been reported. - Consanguinity substantially raises risk in outbred populations (case series from consanguineous Arab families reported). - Founder mutations: c.943C>T (p.Pro315Ser) is the most common allele in the Swedish founder population (northern Sweden, Västerbotten); c.1297_1298delGA (p.Glu433Argfs*3) is the most common allele among broader European patients. Both arise from single recurrent haplotypes (Journal of Human Genetics, 2019, PMID for founder-effect study on 35 patients). - Carrier frequency reaches ~1% in northern Sweden due to founder effect.

Environmental/other risk factors: None identified — SLS is purely genetic; there is no described environmental trigger, infectious cause, or acquired risk factor. Preterm birth is a consequence rather than a cause (see Phenotypes below).

Protective factors: None described; missense alleles retaining partial residual FALDH activity are associated with milder phenotypes (genotype-phenotype correlation; JIMD Reports 2020, "the mild end of the phenotypic spectrum," PMC7203653).

Gene-environment interaction: Not established as a feature of this disease; it behaves as a straightforward Mendelian recessive disorder.

3. Phenotypes

Classic triad (onset: infancy/early childhood, essentially universal): - Ichthyosis (HP:0008064): present at birth or within the first year; ranges from erythematous, hyperkeratotic skin to a collodion-membrane presentation; predominantly flexural, sparing central face. Distinctively pruritic — a feature that differentiates SLS from most other congenital ichthyoses (this pruritus is attributed to leukotriene B4 accumulation, see Mechanism). HPO: Ichthyosis (HP:0008064), Hyperkeratosis (HP:0000962), Dry skin (HP:0000958), Erythema (HP:0010783), Pruritus (HP:0000989). - Spastic diplegia/tetraplegia (HP:0001285/HP:0002510): motor milestone delay (sitting, crawling, walking); lower limbs more severely affected than upper; hypertonia, brisk deep tendon reflexes, extensor plantar responses; most patients become wheelchair-dependent by adolescence. Progressive early in life but largely static thereafter. - Intellectual disability (HP:0001249): mild-to-moderate in most; developmental age typically plateaus around 5–6 years; IQ range reported 25–75. Notably "no cognitive deterioration at least during the first three to four decades of life" in most patients (Dove Press review, PMID 32021380 — TACG 2020).

Additional phenotypes: - Glistening white retinal dots / juvenile macular dystrophy / crystalline maculopathy — pathognomonic when present but may not appear until later childhood; often associated with photophobia. HPO: Macular dystrophy (HP:0007754), Retinal pigment epithelial atrophy, Photophobia (HP:0000613), Abnormality of retinal pigmentation (HP:0007703). - Speech abnormality/dysarthria (HP:0001260): pseudobulbar dysarthria, correlating with cognitive level. - Seizures (HP:0001250): affect ~35–40% of patients; usually generalized tonic-clonic; generally controllable with standard antiepileptics; interictal EEG often normal, though nonspecific epileptiform activity is reported in some. - Short stature, skeletal abnormalities (kyphosis, scoliosis), dental enamel abnormality, corneal erosions, microcephaly, hypotonia (axial, in infancy) are variably reported per HPO annotations. - Preterm birth: reported in ~73% of a Dutch cohort (median gestational age 36 weeks), attributed to elevated leukotriene B4 in amniotic fluid/abnormal lipid metabolism (Staps et al., JIMD Reports 2020).

Severity/progression: Broad phenotypic spectrum from severe classic presentations to very mild forms with near-normal intelligence and minor skin/neurologic findings (PMC7203653, "the mild end of the phenotypic spectrum," 2020). Rare neuroregressive courses have been reported in children/adolescents, usually associated with uncontrolled seizures (a "Neurodegenerative Phenotype Associated with SLS," PMC8458237).

Quality of life impact: Chronic pruritus is described as particularly distressing ("agonising pruritus" — Willemsen et al., zileuton trial, PMID 11795678); mobility limitations (wheelchair dependence) and speech impairment materially affect independence; visual impairment from macular dystrophy adds further burden. No validated disease-specific QOL instrument was identified in this search; general pruritus and mobility scales have been used in clinical trials.

4. Genetic/Molecular Information

Causal gene: ALDH3A2 (aldehyde dehydrogenase 3 family member A2; formerly FALDH gene), chromosome 17p11.2, ~31 kb, 11 exons; two transcripts (a 485-aa major isoform from exons 1–10, and a 508-aa FALDHv variant including exon 9′) differing at the C-terminus that anchors the enzyme to the ER/microsomal membrane.

Variant spectrum: >90–100+ unique variants catalogued (LOVD database, ~178 patients compiled): missense/nonsense substitutions, small insertions/deletions, splice-site defects, and complex rearrangements including large deletions (~5% of mutant alleles; ranging from 1–2 nt up to a 1.44-Mb contiguous gene deletion). Most missense variants severely reduce catalytic activity; a subset retain residual activity with altered kinetics/stability, correlating with milder phenotypes.

Founder/recurrent alleles: - c.943C>T (p.Pro315Ser) — Swedish founder mutation, single haplotype. - c.1297_1298delGA (p.Glu433Argfs*3) — common in broader European ancestry patients.

Variant classification: ClinVar contains numerous pathogenic/likely-pathogenic ALDH3A2 entries linked to SLS (e.g., RCV000001709, RCV000001705). ACMG/AMP classification is used clinically; no large gnomAD-based carrier-frequency study was identified in this search beyond the Swedish 1% carrier estimate in Västerbotten.

Functional consequence: Loss-of-function (enzyme deficiency) — no gain-of-function or dominant-negative mechanism described. Both germline alleles must be pathogenic (biallelic); no somatic form exists (this is a congenital metabolic disease, not neoplastic).

Modifier genes: None established; phenotypic variability (including among siblings sharing the same genotype) is documented (PMID 16476818, "Phenotypic variability among adult siblings with SLS") but no specific modifier locus has been identified.

Epigenetics: No disease-specific epigenetic mechanism reported in the literature surveyed.

Chromosomal abnormalities: Not a chromosomal disorder per se, though large contiguous-gene deletions spanning ALDH3A2 and neighboring genes have been reported as a subset of causal alleles.

5. Environmental Information

No environmental toxins, occupational exposures, or lifestyle factors contribute to disease causation — SLS is fully genetically determined. Dietary fat intake modulates symptom severity (see Treatment) rather than causing disease. No infectious trigger is implicated.

6. Mechanism / Pathophysiology

Primary defect: FALDH (fatty aldehyde dehydrogenase, EC 1.2.1.48) normally oxidizes long-chain fatty aldehydes to fatty acids using NAD+. Deficiency causes accumulation of long-chain aliphatic fatty aldehydes and their reduction products, fatty alcohols (higher relative accumulation of octadecanol vs. hexadecanol in plasma).

Causal chain — multiple convergent metabolic disruptions: 1. Fatty alcohol/aldehyde accumulation → covalent adduct formation with cellular macromolecules (proteins, phospholipids) → cytotoxicity. Aldehydes themselves are hard to detect directly because they are highly reactive and rapidly form adducts (e.g., increased N-alkyl-phosphatidylethanolamine as an indirect marker). 2. Ether glycerolipid/plasmalogen metabolism: FALDH normally participates in degrading the alkyl chain cleaved from ether lipids; deficiency disrupts plasmalogen turnover. Plasmalogens comprise 40–50% of myelin phosphatidylethanolamine, linking this pathway to the CNS dysmyelination phenotype (PMC7689726, "Disturbed brain ether lipid metabolism and histology in SLS"). 3. Leukotriene B4 (LTB4) metabolism: FALDH normally oxidizes ω-aldehyde-LTB4 to ω-carboxy-LTB4 (inactivation step). SLS patients show markedly elevated urinary LTB4 and ω-hydroxy-LTB4 with absent ω-carboxy-LTB4 — "the only condition described with profound urinary excretion of LTB4" (Willemsen et al., J Neurol Sci 2001, PMID region cited above). LTB4, a potent chemoattractant/pruritogen, is implicated in both the intractable pruritus and possibly the high rate of preterm birth (elevated amniotic LTB4). 4. Phytol/phytanic acid and isoprenoid alcohol metabolism: FALDH also participates in oxidation of phytol and mevalonate-pathway branched-chain alcohols; deficient in vitro, though these compounds do not accumulate systemically in patients.

Cutaneous pathogenesis: Accumulated fatty aldehydes/alcohols/ether glycerolipids/wax esters in keratinocytes cause abnormal lamellar body formation and secretion in the stratum granulosum (misshapen, granular-content or empty lamellar bodies), impairing epidermal barrier lipid delivery to the stratum corneum → ichthyosis.

Neurological pathogenesis: Neuronal degeneration in cortex and basal ganglia, white-matter demyelination/dysmyelination, and Purkinje cell loss have been reported histopathologically. MRI shows periventricular white-matter T2/FLAIR hyperintensity (frontal/parieto-occipital predominant, cerebellum typically spared) attributed to abnormal myelin maintenance rather than active demyelination. Proton MR spectroscopy reveals a characteristic accumulated-lipid peak at 1.3 ppm (and ~0.8–0.9 ppm), thought to represent accumulated fatty alcohols/metabolites (hexadecanol/octadecanol) — a distinctive, near diagnostic imaging biomarker (AJNR 2004; PMC7056198, "Proton MR Spectroscopy of Sjögren-Larsson's Syndrome").

Mouse model mechanistic insight: Aldh3a2 knockout mice show impaired long-chain-base (sphingolipid precursor) metabolism in neurons, reduced 2-hydroxygalactosylceramide (a myelin-important lipid, via secondary fatty acid 2-hydroxylase inactivation), and behavioral correlates of ataxia/anxiety (light-induced), supporting the CNS lipid-mediated mechanism (PMID 30085884).

Suggested ontology terms: - GO (biological process): fatty aldehyde metabolic process (GO:0033306-adjacent), aldehyde metabolic process (GO:0006081), leukotriene metabolic process (GO:0006691), ether lipid metabolic process, myelination (GO:0042552), keratinocyte differentiation (GO:0030216), lamellar body organization. - GO (cellular component): endoplasmic reticulum membrane (GO:0005789), peroxisome (GO:0005777) — sites of ALDH3A2 localization; lamellar body. - CL: keratinocyte (CL:0000312), oligodendrocyte (CL:0000128), Purkinje cell (CL:0000121), cortical neuron. - CHEBI: hexadecanol, octadecanol, leukotriene B4 (CHEBI:15647), fatty aldehyde.

7. Anatomical Structures Affected

Organ level: Primary — skin (UBERON:0002097) and central nervous system (brain/spinal cord white matter, UBERON:0002240/0002316); secondary — retina/macula (UBERON:0000966), affecting the visual system; skeletal system (kyphoscoliosis, short stature); dental structures (enamel).

Tissue/cell level: Epidermis (stratum granulosum/stratum corneum keratinocytes), cerebral/cerebellar white matter oligodendrocytes and myelin, cortical and basal ganglia neurons, Purkinje cells (cerebellum), retinal pigment epithelium/macula.

Subcellular level: Endoplasmic reticulum/microsomal membrane (FALDH's primary localization) and peroxisome; lamellar bodies (keratinocyte-specific organelle) — GO Cellular Component: ER membrane (GO:0005789), peroxisomal membrane (GO:0005778).

Localization: Skin involvement is generalized but flexural-predominant with facial sparing; CNS white-matter changes are periventricular, frontal/parieto-occipital predominant, bilateral/symmetric (not lateralized); ocular findings are typically bilateral macular.

8. Temporal Development

Onset: Congenital/neonatal for ichthyosis (present at birth or first weeks of life, sometimes as a collodion membrane); spasticity and developmental delay become apparent in infancy (delayed sitting/crawling/walking); macular dystrophy may not be visible until later childhood.

Progression: Skin and motor/spasticity findings are most dynamic in early childhood, then largely static/non-progressive through adulthood — a key distinguishing feature from true neurodegenerative leukodystrophies. Cognitive function is reported stable through the first 3–4 decades in most patients. A minority show an atypical neuroregressive course, usually linked to uncontrolled seizures (PMC8458237; PMC6114270, "Neurodegeneration in an adolescent with SLS: a decade-long follow-up").

Course pattern: Chronic, lifelong, predominantly stable/non-progressive rather than episodic or relapsing-remitting; no spontaneous remission described. Pruritus can fluctuate.

Critical periods: Early diagnosis enabling aggressive physiotherapy is emphasized as improving motor outcome (escholarship.org review, "Importance of early diagnosis and aggressive physiotherapy").

9. Inheritance and Population

Inheritance: Autosomal recessive; complete penetrance for biallelic pathogenic variants; expressivity is variable (documented phenotypic variability even among siblings with identical genotype, PMID 16476818).

Epidemiology: Overall Swedish prevalence ~1 in 250,000 (~0.4/100,000); dramatically higher in Västerbotten, northern Sweden at 8.3 per 100,000 due to a founder effect and historically higher local consanguinity/isolation. Global prevalence elsewhere is not well quantified but the disease is reported worldwide (Europe, Middle East consanguineous families, other regions).

Founder effects/carrier frequency: Carrier frequency up to ~1% in northern Sweden; distinct founder mutations described in different populations (Swedish c.943C>T; broader European c.1297_1298delGA), consistent with multiple independent founder events globally (Journal of Human Genetics 2019 founder-effect study of 35 patients).

Consanguinity: A recognized risk factor in outbred populations outside the Swedish founder cluster (e.g., consanguineous Arab families with multiple affected siblings reported).

Population demographics: No strong sex predilection reported (autosomal recessive, expected ~1:1 M:F). Age distribution reflects a pediatric-onset, lifelong chronic disease with survival into adulthood in most contemporary cohorts.

10. Diagnostics

Laboratory/biochemical tests: - FALDH enzyme activity assay in cultured skin fibroblasts, or fatty alcohol:NAD+ oxidoreductase (FAO) activity — deficient in both, providing a combined diagnostic test. - Urinary biomarkers: elevated LTB4 and ω-hydroxy-LTB4 with absent ω-carboxy-LTB4 — a non-invasive diagnostic approach. - Plasma long-chain fatty alcohol accumulation (octadecanol > hexadecanol).

Imaging: Brain MRI — periventricular white-matter T2/FLAIR hyperintensity; proton MR spectroscopy showing a characteristic 1.3 ppm (and 0.8–0.9 ppm) lipid peak is described as near-diagnostic/definitive in the correct clinical context (MDedge, "Definitive Diagnosis on Magnetic Resonance Spectroscopy"; AJNR 2004).

Ophthalmologic exam: Fundoscopy for glistening white retinal dots (crystalline maculopathy) — pathognomonic when present.

Histopathology: Skin biopsy showing disrupted lamellar body formation/secretion in the stratum granulosum (electron microscopy).

Genetic testing: Sequencing of ALDH3A2 (single-gene test or as part of an ichthyosis/leukodystrophy/spastic-paraplegia gene panel); biallelic pathogenic variants confirm diagnosis. Available via GTR (Genetic Testing Registry) and clinical laboratories (e.g., Myriad Foresight carrier screen lists SLS).

Clinical criteria: Diagnosis is typically made by around age 3 based on the classic triad plus supportive enzyme/biochemical/genetic confirmation; clinical suspicion should arise in any child with ichthyosis plus spastic diplegia/tetraplegia — even with normal intelligence, since the mild end of the spectrum exists.

Differential diagnosis: Cerebral palsy (a common misdiagnosis before ichthyosis is recognized as linked), other congenital ichthyosiform erythrodermas/collodion baby syndromes (non-pruritic, distinguishing feature), other leukodystrophies/hereditary spastic paraplegias, and other neuroichthyotic syndromes (e.g., Refsum disease, trichothiodystrophy — differentiated by lipid/biochemical/genetic profile).

Screening: No population newborn screening program identified; carrier screening is feasible in high-risk populations (e.g., northern Swedish ancestry) and via expanded carrier panels; prenatal/preimplantation testing possible once familial variants are known.

11. Outcome/Prognosis

Survival: Most patients now survive well into adulthood; earlier reports suggested life expectancy roughly halved relative to the general population (historical estimates as low as 15–26 years), but more recent clinical experience is more favorable, especially with modern supportive care.

Disease course/morbidity: Predominantly non-progressive motor/cognitive course after an early developmental period — most patients plateau rather than continuing to decline. Chronic morbidity centers on: wheelchair dependence (progressive spasticity to non-ambulation in many), speech impairment, visual impairment from macular dystrophy, and persistent pruritus/skin discomfort. A minority experience atypical neuroregression, generally associated with poorly controlled seizures.

Complications: Contractures, orthopedic deformities (kyphoscoliosis) from long-standing spasticity, corneal erosions, dental enamel defects, growth/short stature.

Prognostic factors: Genotype (missense variants with residual FALDH activity → milder phenotype); seizure control (uncontrolled seizures associated with neuroregressive courses); early diagnosis and aggressive physiotherapy improving functional motor outcomes.

12. Treatment

Management is currently entirely symptomatic; there is no FDA-approved disease-modifying therapy.

Pharmacotherapy — skin: - Topical emollients/keratolytics: urea creams (2–10%), used 1–2×/day (MAXO:0000004-adjacent topical care; general symptomatic skin care). - Topical vitamin D analogue: calcipotriol, reported to improve ichthyosis. - Systemic retinoids: acitretin — effective for cutaneous symptoms with good tolerability in reported cohorts (short-acting retinoid preferred over older agents like etretinate for pediatric use due to tissue-storage concerns). MAXO/NCIT: Pharmacotherapy (NCIT:C15986) with therapeutic_agent acitretin (CHEBI). - Topical cholesterol/lovastatin (lipid replacement approach) — reported to give slight improvement.

Pharmacotherapy — pruritus/leukotriene pathway: - Zileuton (5-lipoxygenase inhibitor, blocks LTB4/cysteinyl-leukotriene synthesis): open-label trial in 5 patients (3 months) showed significant improvement in pruritus score (P=0.006), general well-being, and EEG background activity (Willemsen et al., Eur J Pediatr 2001, PMID 11795678). However, a subsequent double-blind, placebo-controlled crossover trial in 10 patients did not replicate the pruritus benefit; the authors still recommended a 4–6 week therapeutic trial in patients with severe disabling pruritus (Acta Derm Venereol 2016 zileuton RCT).

Dietary therapy: Fat-restricted diet (~30% of calories from fat) with medium-chain triglyceride (MCT) supplementation and adjusted essential fatty acid (linoleic:linolenic) ratios has been tried, reducing substrate for pathological long-chain fatty alcohol synthesis; results are inconsistent, with occasional cutaneous benefit but no convincing effect on neurologic symptoms — early intervention appeared to help more in reported cases.

Neurological/spasticity management: - Oral baclofen, benzodiazepines, muscle relaxants, anticholinergics. - Intrathecal baclofen — favorable response reported. - Physical/occupational therapy (MAXO:0000011 physical therapy) — emphasized as critical, especially with early diagnosis. - Orthopedic surgery: tendon lengthening, adductor release, dorsal rhizotomy (MAXO:0000004/NCIT:C16186 orthopedic surgical procedure) for contracture/spasticity management.

Seizure management: Standard antiepileptic drugs; seizures are usually controllable.

Experimental/investigational therapies: - ADX-102 (reproxalap) 1% topical cream — an aldehyde-scavenging small molecule tested in the industry-sponsored RESET Trial (NCT03445650), a Phase 3 randomized, double-blind, vehicle-controlled trial (Aldeyra Therapeutics) targeting ichthyosis in SLS; Part 1 enrolled 11 subjects (2018–2020). A related compound, ADX-629, has also been studied (NCT05443685). - Aldehyde scavenger NS2 — reduces N-alkyl-phosphatidylethanolamine formation in FALDH-deficient CHO cells and mouse models; early-phase clinical development noted. - PPAR-α agonist bezafibrate — increased ALDH3A2 expression and residual enzyme activity in fibroblasts from missense-mutation patients in vitro; not yet clinically trialed. - ALDH activator Alda-89 — stimulates residual FALDH activity ~3-fold in vitro; no clinical trials yet. - JNK pathway inhibitors — rationale based on trans-2-hexadecenal-induced JNK activation/apoptosis in model systems. - Gene therapy: rAAV-2-mediated FALDH gene transfer restored ~15-fold FALDH activity (60–70% of normal) in transduced SLS keratinocytes in vitro, with 84% of cells regaining resistance to long-chain aldehyde toxicity; lentiviral hematopoietic stem cell gene therapy has been tested in mouse models. Clinical translation remains preliminary; transgenic mouse overexpression models have been hampered by neonatal lethality.

Natural history study: NCT01971957 ("Sjogren-Larsson Syndrome: Natural History, Clinical Variation and Evaluation of Biochemical Markers") — ongoing NIH-affiliated natural history study informing future trial design.

13. Prevention

Primary prevention: Not applicable in the traditional sense (no environmental exposure to avoid); genetic counseling is the principal primary-prevention tool for at-risk couples (both carriers), especially in high-prevalence founder populations (northern Sweden) or consanguineous unions.

Secondary prevention/screening: Carrier screening in high-risk populations (feasible via targeted panels, e.g., commercial expanded carrier screens); prenatal diagnosis and preimplantation genetic diagnosis (PGD) are technically available once familial ALDH3A2 variants are identified, though no population-wide newborn screening program was identified in this search.

Tertiary prevention: Early clinical diagnosis (target by ~age 3) paired with aggressive physiotherapy is repeatedly emphasized in the literature as improving functional motor outcomes and preventing/minimizing contractures; regular ophthalmologic surveillance for macular dystrophy and dental/orthopedic follow-up to manage secondary complications.

Genetic counseling: Standard autosomal-recessive recurrence-risk counseling (25% recurrence per pregnancy for carrier couples); relevant in populations with known founder mutations or consanguinity.

14. Other Species / Natural Disease

No naturally occurring veterinary/companion-animal form of SLS (spontaneous ALDH3A2 deficiency) was identified in this search — this appears to be a human-specific reported condition without an OMIA veterinary entry found. The relevant cross-species information is limited to engineered model organisms (see below) rather than natural disease in other species.

Orthologous gene: Aldh3a2 (mouse; NCBI Gene ortholog) — used to generate the knockout model discussed below.

15. Model Organisms

Mouse model (Aldh3a2 knockout, mammalian genetic model): - Aldh3a2 KO mice show impaired long-chain-base (sphingolipid precursor) metabolism in neurons and reduced 2-hydroxygalactosylceramide (a myelin-relevant lipid, via secondary fatty acid 2-hydroxylase inactivation) in brain tissue. - Behavioral phenotype recapitulation: increased paw slips on balance-beam testing (motor/coordination deficit) and light-induced anxiety (potentially modeling photophobia), corresponding to some human SLS features (PMID 30085884). - Limitations: Transgenic/overexpression mouse models attempting to model the disease more fully have suffered neonatal lethality, limiting some in vivo therapeutic testing; the KO model does not fully recapitulate the ichthyosis or spasticity phenotype seen in humans, so it is used primarily for CNS lipid/mechanistic studies rather than full disease modeling.

Cellular models: - Patient-derived dermal fibroblasts and keratinocytes — standard for FALDH/FAO enzyme activity assays and gene-therapy vector testing (rAAV-2 FALDH transduction studies). - iPSC-derived oligodendrocyte-lineage cells from SLS patients — recently established to study accumulation of ether phospholipids and CNS-relevant lipid pathology in a human cellular system (PMC11608845, 2024). - CHO (Chinese hamster ovary) cell lines engineered to be FALDH-deficient — used for aldehyde-scavenger (NS2) and gene-transfer proof-of-concept studies.

Applications: These models collectively support study of (1) keratinocyte lamellar body/lipid barrier dysfunction, (2) CNS myelin lipid abnormalities, and (3) therapeutic strategies (gene transfer, aldehyde scavenging, enzyme activators) prior to human trials.

Summary Table of Key Ontology Term Suggestions

Table (click to expand)

Category	Suggested terms
Disease	MONDO:0010031; OMIM:270200; ORPHA:816; DOID:14501
Gene	HGNC:403 ALDH3A2; OMIM:609523
Phenotype (HP)	HP:0008064 Ichthyosis; HP:0001285 Spastic tetraplegia; HP:0002510 Spastic diplegia; HP:0001249 Intellectual disability; HP:0007754 Macular dystrophy; HP:0000613 Photophobia; HP:0000989 Pruritus; HP:0001250 Seizure; HP:0001260 Dysarthria
GO (process)	Aldehyde metabolic process; leukotriene metabolic process; ether lipid metabolic process; myelination; keratinocyte differentiation
GO (component)	Endoplasmic reticulum membrane (GO:0005789); peroxisome (GO:0005777)
CL	Keratinocyte (CL:0000312); oligodendrocyte (CL:0000128); Purkinje cell (CL:0000121)
UBERON	Skin epidermis; white matter of CNS; macula
CHEBI	Leukotriene B4; hexadecanol; octadecanol
MAXO	Physical therapy (MAXO:0000011); surgical procedure (MAXO:0000004)