Haploinsufficiency of KPNA7 causes otosclerosis, likely due to the release of import inhibition of PTHrP and the reactivation of chondrogenesis in the globuli interossei
Bibliographic record
Abstract
Abstract Otosclerosis is a genetic bone disorder restricted to the otic capsule and a common cause of conductive hearing loss with both familial and sporadic cases. To date, 14 genomic loci ( OTSC ) and four underlying OTSC genes ( MEPE , SERPINF1, FOXL1, SMARCA4) have been identified in autosomal dominant families. A combined genetic/genomics approach on five affected siblings of Northern European ancestry from the island of Newfoundland, Canada identified a premature stop mutation in Karyopherin subunit α7 ( KPNA7 , c.49C>T, p.R17X). KPNA7 maps to OTSC2 (7q22.1) and encodes the newest of the seven-member importin-α family of nuclear transporters and plays a critical role in early embryonic cleavage events and zygotic genome activation. Previous studies reveal that recessive KPNA7 variants cause skeletal abnormalities, including scoliosis and ocular hypertelorism in two sisters with Partial Corpus Callosum Agenesis-Cerebellar Vermis Hypoplasia With Posterior Fosa Cysts Syndrome and more recently, have been implicated in preimplantation embryo arrest (PREMBA) (OMIM 614107). Interestingly, KPNA7 is also a maternal factor with an exclusively embryonic role and likely inhibits non-classical NLS transport of PTHrP, a known activator of chondrogenesis. We propose that KPNA7 haploinsufficiency causes a failure in nuclear transport inhibition of PTHrP in the quiescent embryonic cells of the globuli interossei in the otic capsule and re-activates chondrogenesis. The KPNA7 discovery provides new insights into the pathogenesis of otosclerosis and potential for targeted therapies. Author Summary Otosclerosis is a distinctly human genetic bone disorder of the otic capsule and a major cause of progressive hearing loss in young adults, particularly in females. Even though otosclerosis has been recognized as a distinct entity for a long time, both its pathogenesis and restriction to the otic capsule remains a mystery. Here, we use a combined genetic/genomics approach to identify a premature stop mutation in five affected siblings of Northern European ancestry from the island of Newfoundland, Canada. KPNA7 encodes the newest of the seven-member importin-α family of nuclear transporters and plays a critical role in early embryonic cleavage events and zygotic genome activation. Based on the unique features of the otic capsule, we hypothesize that the premature stop mutation in KPNA7 leads to haploinsufficiency causing a failure in nuclear transport inhibition of PTHrP and reactivates chondrogenesis in the otherwise quiescent embryonic cells within the otic capsule. The KPNA7 discovery provides new insights into the pathogenesis of otosclerosis and potential for targeted therapies.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".