Canavan disease: Carrier‐frequency determination in the Ashkenazi Jewish population and development of a novel molecular diagnostic assay
Bibliographic record
Abstract
Canavan disease (CD) is an autosomal recessive progressive neurodegenerative disorder prevalent in the Ashkenazi Jewish (AJ) population. The carrier rate for the most common mutations that cause CD in the AJ population is often quoted as 1:37-1:40. This is not supported by our finding of only two diagnosed cases of CD in the last 20 years in the Toronto AJ population of 160,000 and an estimated birth rate of 1,500-2,000 per year. Therefore, we embarked on a prevalence cross-sectional screening study to determine the carrier rate of CD in this population. In order to perform low-cost, high-throughput population testing for CD using molecular techniques, we first developed a novel molecular assay using multiplex fluorescent allele specific polymerase chain reaction (PCR) to test for the three most common mutations causing CD in the AJ population (A854C, C693A, C914A) and a neutral polymorphism at the site of the C693A mutation. During testing it was noted that individuals who were carriers of the A854C mutation also had a T polymorphism at the site of the C693A mutation (Y231X). We confirmed that in all A854C carriers the 854C mutation was in disequilibrium with the 693T polymorphism, indicating a founder chromosome for the A854C mutation in the AJ population. Twenty-five carriers were found from 1,423 samples yielding a carrier rate of 1:57, differing from the widely quoted frequency of 1:40 and supporting our observed frequency of disease.
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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 | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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".