| Domain | Finding | Quantitative detail | Evidence type/strength |
|---|---|---|---|
| Cohort size / age | Foundational dominant FAR1 cohort comprised 12 affected individuals evaluated clinically and functionally | Ages at study: 2-19 years; all had neurological symptoms in the first years of life (pqac-00000000, pqac-00000010) | Human clinical cohort with patient-derived fibroblast functional studies; strongest direct evidence available (pqac-00000000, pqac-00000008) |
| Variant spectrum | All reported pathogenic dominant variants in the foundational cohort altered Arg480 | p.Arg480Cys: 7/12; p.Arg480His: 4/12; p.Arg480Leu: 1/12 (pqac-00000004) | Human genetic evidence from de novo recurrent missense variants; strong (pqac-00000004) |
| Inheritance | Disease mechanism is monoallelic, autosomal dominant, arising through de novo variants | 12/12 reported as de novo heterozygous FAR1 variants (pqac-00000000, pqac-00000004) | Human trio/exome-based evidence; strong (pqac-00000000, pqac-00000011) |
| Cardinal neurologic phenotype | Spastic paraparesis / pyramidal tract dysfunction is the core neurologic feature | 12/12; described with lower-limb hypertonia, truncal hypotonia in 6/12, and ankle clonus (pqac-00000010) | Human clinical cohort; strong (pqac-00000010) |
| Ocular phenotype | Bilateral cataracts are universal in the foundational cohort | 12/12 total; congenital in 5/12 and acquired/juvenile in 7/12 (pqac-00000010) | Human clinical cohort; strong (pqac-00000010) |
| Developmental phenotype | Speech and motor delay are common; intellectual disability is less frequent | Speech delay 10/12; gross motor developmental delay reported in most; cognitive delay / intellectual disability 3/12 (pqac-00000000, pqac-00000010) | Human clinical cohort; moderate-to-strong (pqac-00000000, pqac-00000001) |
| Seizures / treatment outcome | Early-life seizures were common and often treatment-responsive | Seizures in 8/12, mainly in the first months of life; treated with barbiturates, levetiracetam, and/or oxcarbazepine; antiepileptics discontinued without recurrence in 4/8 (pqac-00000000, pqac-00000010) | Human clinical cohort with follow-up; moderate-to-strong (pqac-00000000, pqac-00000010) |
| Neuroimaging | Brain MRI usually non-diagnostic or normal | Normal in 10/12; 1 had abnormal temporal lobe morphology with ventricular prominence and normal white matter; 1 had benign enlargement of subarachnoid spaces (pqac-00000010) | Human clinical cohort; strong for available sample (pqac-00000010) |
| Biochemical finding | Dominant disease shows elevated plasmalogens, opposite to recessive FAR1 deficiency | Untreated patient fibroblasts had mean C16:0-plasmalogen levels about twofold higher than controls; FAR1 protein levels were threefold higher than HDG-treated controls (pqac-00000010) | Patient fibroblast biochemistry/immunoblot; strong mechanistic evidence (pqac-00000010) |
| Enzyme / localization | FAR1 catalytic function and peroxisomal localization are preserved | FAR1 enzyme activity preserved; mutant FAR1 localized normally to peroxisomes in patient fibroblasts (pqac-00000011) | Patient-derived cell functional assays and immunofluorescence; strong (pqac-00000011) |
| Lipidomics | Ether lipids accumulate with reciprocal depletion of corresponding nonether lipids | Increased PC[O], PE[O], DG[O], TG[O]; examples in figure summary include PE[O] about 2.5x, DG[O] about 3.3x, TG[O] about 5.8x versus controls; PUFA-rich PC[O] species particularly increased (pqac-00000009, pqac-00000012) | Patient fibroblast lipidomics in 3 analyzed patients vs 3 controls; strong for cellular biochemical phenotype (pqac-00000009, pqac-00000012) |
| Flux evidence | Ether lipid synthesis from exogenous substrate is increased | C17:0-alcohol incorporation into LPC(O-17:0) was fourfold higher in patients; C17:0-acid incorporation into nonether LPC(17:0) was comparable between patients and controls (pqac-00000003, pqac-00000012) | Patient fibroblast metabolic labeling; strong direct functional evidence (pqac-00000003, pqac-00000012) |
| Mechanism | Arg480 variants disrupt plasmalogen-dependent negative feedback on FAR1 stability, causing uncontrolled ether lipid synthesis | Arg480 lies in the transmembrane region (aa 466-483); elevated plasmalogens failed to lower FAR1 protein in patient cells after HDG treatment, unlike controls (pqac-00000009, pqac-00000010, pqac-00000007) | Human patient-derived mechanistic cell biology supported by review synthesis; strong (pqac-00000009, pqac-00000013) |
| Diagnostic implications | FAR1 should be considered in patients with spastic paraparesis plus bilateral cataracts; plasmalogens can support functional interpretation | Authors recommend adding FAR1 to hereditary spastic paraplegia, cerebral palsy, and juvenile cataract panels; erythrocyte plasmalogen measurement may be informative because both high and low values can indicate FAR1-related pathology (pqac-00000000, pqac-00000003, pqac-00000012) | Expert recommendation grounded in cohort and functional data; moderate-to-strong (pqac-00000000, pqac-00000012) |
| Evidence limitations | Evidence base remains very small and recent follow-up/expansion papers were not fully retrievable in this tool environment | Direct detailed extraction currently rests mainly on one 12-patient cohort; additional 2022-2024 reports were identified by metadata but not fully available here for verification (pqac-00000008, pqac-00000013) | Limitation statement based on available retrieved sources; important caution for knowledge-base use (pqac-00000008, pqac-00000013) |


*Table: This table summarizes the strongest directly retrievable evidence for monoallelic FAR1 gain-of-function syndrome, focusing on recurrent Arg480 variants, phenotype frequencies, biochemical mechanism, and diagnostic implications. It is useful as a compact evidence map for knowledge-base extraction while clearly flagging current evidence limitations.*