Computational evidence supporting reclassification of NM_153700.2(STRC):c.4976A>C from Variant of Uncertain Significance (VUS) to Likely Pathogenic. Includes AlphaMissense prediction, AlphaFold structural context, ACMG criteria, and gene therapy landscape.
Every possible amino acid substitution at position 1659 is predicted Likely Pathogenic. This position is structurally invariant: any change breaks the protein.
Stereocilin (Q7RTU9, 1775 aa) from AlphaFold v6. Position E1659 highlighted in magenta. Drag to rotate, scroll to zoom.
Color: pLDDT confidence (blue=high, red=low)
Glutamic acid side chain shown as sticks
| Criterion | Strength | Evidence |
|---|---|---|
| PM3 | Moderate | Detected in trans with pathogenic whole-gene deletion (confirmed paternal) |
| PP3_Moderate | Moderate | AlphaMissense 0.9016 + REVEL 0.65 concordant (Pejaver 2022 threshold) |
| PM2_Supporting | Supporting | Absent from gnomAD (0 alleles in 251,000+ individuals) |
2 Moderate + 1 Supporting = Likely Pathogenic per ACMG/AMP 2015 combining rules
PMC12784207 | DOI: 10.1002/ctm2.70571 | Clinical and Translational Medicine, Jan 2026
Current STRC gene therapy requires two AAV vectors because the gene (5325 bp) exceeds the single-AAV packaging limit (~4400 bp usable). AlphaFold structural analysis suggests a single-vector approach may be possible.
AlphaFold predicts stereocilin's structure with varying confidence along the protein. The N-terminal region (residues 1-615) has very low confidence (pLDDT < 50), indicating it is likely intrinsically disordered with no stable 3D structure. The functional core starts around residue 616.
All regions have pLDDT < 50 (no stable structure predicted)
3984 bp fits in single AAV (<4400 bp limit)
This approach has proven precedent. The dystrophin gene (11,000 bp) was too large for any AAV. Researchers created "micro-dystrophin" by removing non-essential spectrin-like repeats, fitting it into a single AAV. This is now in Phase 3 clinical trials (Sarepta SRP-9001). The same principle: identify the structural core, remove disordered/redundant regions, preserve function. Nobody has tried this for STRC yet.
Important: This is a computational hypothesis based on AlphaFold structural predictions. It requires experimental validation: does mini-stereocilin fold correctly? Does it localize to stereocilia tips? Does it form horizontal top connectors and tectorial membrane attachments? These questions need wet-lab work. But the structural data strongly suggests the N-terminal region is dispensable, and a single-AAV mini-STRC approach deserves investigation.
STRC has a nearly identical pseudogene (STRCP1) located adjacent on chromosome 15q15.3. This causes most standard computational tools to fail or return unreliable results for STRC variants:
AlphaMissense is uniquely valuable for STRC because it predicts pathogenicity from protein structure, bypassing the sequence-alignment step where pseudogene STRCP1 causes other tools to fail. REVEL (0.65) also provides a concordant prediction, using an ensemble approach that partially mitigates this issue.
As of March 2026, there are no registered clinical trials specifically for STRC/DFNB16 gene therapy. Preclinical evidence (Iranfar 2026, Shubina-Oleinik 2021) supports feasibility. First-in-human trials expected 2028-2029.
Source: ClinicalTrials.gov. These OTOF trials establish precedent and regulatory pathway for STRC gene therapy.
I'm a father with no scientific training. I work in technology and creative production. Here is exactly what I did, step by step, so anyone in the same situation can do it too.
Michael's WES report from Hong Kong Children's Hospital listed two STRC variants. One was labeled "Pathogenic" (a whole gene deletion from his father). The other was labeled "Variant of Uncertain Significance" (a single letter change from his mother): c.4976A>C p.(Glu1659Ala). I needed to know: is this second variant actually harmful?
I searched for "STRC" on UniProt and found that stereocilin's ID is Q7RTU9. Then I went to AlphaFold and found the predicted 3D structure of the protein. The confidence score at position 1659 was 95.69 out of 100 (the structure prediction is very reliable at this spot).
AlphaMissense is a tool by Google DeepMind that predicts whether a protein mutation is harmful. I downloaded the predictions for every possible mutation in stereocilin. For position 1659, I searched for "E1659A" (E = Glutamic acid, the original; A = Alanine, Michael's variant).
The result: 0.9016 out of 1.0 (Likely Pathogenic). Anything above 0.564 is considered likely harmful. Then I checked every other possible change at the same position. All 19 alternatives scored above 0.846. This means position 1659 is critical: any change there breaks the protein.
Normally, geneticists use SIFT, PolyPhen-2, and CADD to check variants. I tried all three. They all returned nothing for this variant. The reason: STRC has a "twin" gene next to it on the chromosome (a pseudogene called STRCP1) that confuses these tools. They can't tell the real gene from the copy. This is why AlphaMissense is so important for STRC: it works from the protein structure, not from the DNA sequence, so the pseudogene doesn't affect it.
ACMG is the standard framework geneticists use to classify variants. I learned the rules and applied them to Michael's case:
2 Moderate + 1 Supporting = Likely Pathogenic. That's the rule. The variant should no longer be classified as "uncertain."
I compiled everything into a formal letter and sent it to the genetics laboratory at Hong Kong Children's Hospital, requesting a reclassification review. I also built this website so the evidence is transparent and reproducible.
If the hospital accepts the reclassification, Michael's molecular diagnosis will be complete: biallelic pathogenic STRC. This is a prerequisite for future gene therapy clinical trials. Dual-AAV gene therapy has already restored hearing in STRC-deficient mice (January 2026). Human trials are expected within 2-3 years. Michael will be 7-8 years old.
No accounts needed. No API keys. No programming required (the CSV file can be opened in Excel). Total cost: $0.