A polyadenylation site variant causes transcript-specific BMP1 deficiency and frequent fractures in children
Bibliographic record
Abstract
We had previously published the clinical characteristics of a bone fragility disorder in children that was characterized mainly by lower extremity fractures and a mineralization defect in bone tissue but not on the growth plate level. We have now performed whole-exome sequencing on four unrelated individuals with this phenotype. Three individuals were homozygous for a nucleotide change in BMP1, affecting the polyadenylation signal of the transcript that codes for the short isoform of BMP1 (BMP1-1) (c.*241T>C). In skin fibroblasts of these individuals, we found low levels of BMP1-1 transcript and protein. The fourth individual was compound heterozygous for the c.*241T>C variant in BMP1-1 and a variant in BMP1 exon 15 (c.2107G>C) that affected splicing in both BMP1-1 and the long isoform of BMP1 (BMP1-3). Both the homozygous 3'UTR variant and the compound heterozygous variants were associated with impaired procollagen type I C-propeptide cleavage, as the amount of free C-propeptide in the supernatant of skin fibroblasts was less than in controls. Peripheral quantitative computed tomography showed that all individuals had elevated volumetric cortical bone mineral density. Assessment of iliac bone samples by histomorphometry and quantitative backscattered electron imaging indicated that the onset of mineralization at bone formation sites was delayed, but that mineralized matrix was hypermineralized. These results show that isolated lack of BMP1-1 causes bone fragility in children.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".