Medial Temporal Lobe Dysgenesis and More in a Man with Hypochondroplasia and Epilepsy
Bibliographic record
Abstract
Hypochondroplasia, achondroplasia, and thanatophoric dysplasia are related at the molecular level, all caused by fibroblast growth factor receptor 3 (FGFR3) gene mutations. They differ in severity. FGFR3 has critical roles in fibroblast growth factor (FGF) signalling pathways during bone growth and cerebral cortical development. Mutations of the FGFR3 gene lead to constitutive activation of FGFR3. The well-described brain malformation in thanatophoric dysplasia is characterized by gross abnormalities of temporal lobe patterning and severe dysplasia of the hippocampus. Experimental models suggest that increased proliferation, abnormal migration, and decreased apoptosis are involved. However, reports of the brain findings in hypochondroplasia are based solely on radiologic imaging. We present the neuropathology of a 44 year-old man with hypochondroplasia, epilepsy, and significant intellectual disability. The temporal lobes are enlarged, prominent fissures traverse the inferior temporal surface, and the hippocampus is abnormally folded. Microscopically, the dentate gyrus is variably small or thin and is located near the edge of a gyrus. Ammon’s horn is displaced and meandering. Subicular-like clusters are profuse. Complex gyri resemble microgyria. White matter forms a subpial border in some gyri. In summary: medial temporal lobe dysgenesis. This individual also had many autistic features including stereotypies and head banging. The latter could explain another surprising set of brain abnormalities unrelated to the presumed FGFR3-related syndrome. LEARNING OBJECTIVES This presentation will enable the learner to: 1. Summarize current theories on the pathogenesis of FGFR3-related cortical malformation 2. Describe the brain abnormalities in hypochondroplasia 3. Identify the neuropathology resulting from head banging
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.005 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".