Acardia: Epidemiologic findings and literature review from the International Clearinghouse for Birth Defects Surveillance and Research
Bibliographic record
Abstract
Acardia is a severe, complex malformation of monozygotic twinning, but beyond clinical case series, very few epidemiologic data are available. The goals of this study were to assess the epidemiologic characteristics of acardia from birth defect registries in the International Clearinghouse for Birth Defects Surveillance and Research (Clearinghouse), and compare these findings to current literature. The study included 17 surveillance programs of the Clearinghouse representing 23 countries from North and South America, Europe, China, and Australia. Anonymized individual records with clinical and demographic data were reviewed centrally by clinical geneticists. A literature search was performed. A total of 164 cases of acardia were reported from an underlying cohort of 21.2 million births. Of these, 23% were elective pregnancy terminations. Rates did not vary significantly by maternal age. For many cases, information on pregnancy exposures and genetic testing was missing. However, these limited data did not suggest high rates of chronic illnesses (diabetes, seizure disorders) or lifestyle factors such as smoking. One case had trisomy 13. Major malformations were reported in 2.4% of co-twins. With some basic assumptions, the total prevalence of acardia was estimated at 1 in 50,000-70,000 births, and 1 in 200-280 monozygotic twins. In summary, acardia is a dramatic, probably underreported, and incompletely understood malformation. Studies on its epidemiology and etiology are challenging and still rare. An international collaboration of epidemiologists, clinicians, and geneticists is necessary to understand the etiology, pathogenesis, and occurrence of this severe malformation complex.
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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 | 0.013 | 0.031 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.003 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.003 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.005 |
| 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".