Transcobalamin receptor defect: Identification of two new cases through positive newborn screening for propionic/methylmalonic aciduria and long‐term outcome
Bibliographic record
Abstract
Likely pathogenic variants in CD320 cause transcobalamin receptor defect, a recently discovered inborn errors of cobalamin metabolism. Only 12 cases have been reported to date. There are no long-term clinical and biochemical outcome reports since its first description. In this report, we present two new cases and report their long-term treatment outcome. Two asymptomatic cases were identified through a positive newborn screening for propionic/methylmalonic aciduria. Biochemical abnormalities were normalized on a short course of oral cyanocobalamin (1 mg/day). Direct sequencing of CD320 identified a known pathogenic variant (c.262_264GAG; p.Glu88del) confirming the diagnosis of transcobalamin receptor defect. To date, both patients remain asymptomatic with normal neurodevelopment more than 6 years. Our two new cases with transcobalamin receptor defect due to pathogenic variants in CD320 further expand our knowledge and provide a reassuring long-term good neurodevelopmental outcome. Identification of additional cases requires the consideration of transcobalamin receptor defect in the differential diagnosis of newborns with confirmed positive newborn screening for methylmalonic acidurias.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| 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".