Pseudoxanthoma elasticum overlaps hereditary spastic paraplegia type 56
Bibliographic record
Abstract
PURPOSE: Pseudoxanthoma elasticum (PXE) is a recessive disorder involving skin, eyes and arteries, mainly caused by ABCC6 pathogenic variants. However, almost one fifth of patients remain genetically unsolved despite extensive genetic screening of ABCC6, as illustrated in a large French PXE series of 220 cases. We searched for new PXE gene(s) to solve the ABCC6-negative patients. METHODS: First, family-based exome sequencing was performed, in one ABCC6-negative PXE patient with additional neurological features, and her relatives. CYP2U1, involved in hereditary spastic paraplegia type 56 (SPG56), was selected based on this complex phenotype, and the presence of two candidate variants. Second, CYP2U1 sequencing was performed in a retrospective series of 46 additional ABCC6-negative PXE probands. Third, six additional SPG56 patients were evaluated for PXE skin and eye phenotype. Additionally, plasma pyrophosphate dosage and functional analyses were performed in some of these patients. RESULTS: 6.4% of ABCC6-negative PXE patients (n = 3) harboured biallelic pathogenic variants in CYP2U1. PXE skin lesions with histological confirmation, eye lesions including maculopathy or angioid streaks, and various neurological symptoms were present. CYP2U1 missense variants were confirmed to impair protein function. Plasma pyrophosphate levels were normal. Two SPG56 patients (33%) presented some phenotypic overlap with PXE. CONCLUSION: CYP2U1 pathogenic variants are found in unsolved PXE patients with neurological findings, including spastic paraplegia, expanding the SPG56 phenotype and highlighting its overlap with PXE. The pathophysiology of ABCC6 and CYP2U1 should be explored to explain their respective role and potential interaction in ectopic mineralization.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".