Recurrent trisomy 21: four cases in three generations
Bibliographic record
Abstract
Recurrent trisomy 21: four cases in three generations. While gonadal mosaicism can lead to recurrence of trisomy 21 (T21) for a single couple, the recurrence of free T21 in multiple members of a single pedigree has rarely been reported. We present an unusual pedigree with four cases of Down syndrome (DS) with free T21 were born to four separate women related through three generations of one family. The mothers were aged 18, 21, 29, and approximately 30 years at the time of the births. Using microsatellite markers, we excluded most of chromosome 21, excepting two small regions within 21q11.1 and 21q22.3, as being shared among the mothers of the DS children. However, two members of the pedigree, including one DS mother with a normal G-banded karyotype, carried supernumerary alleles at markers 2503J9TG, D21S369, and D21S215, which span the region from 21pter to 21q11.1. Fluorescence in situ hybridization using a centromeric probe hybridizing to chromosomes 13 and 21 did not reveal a novel location, ruling out a cryptic centromeric translocation between chromosome 21 and any chromosome other than chromosome 13. The level of meiotic recombination on chromosome 21 was unusually high in this family as well. We hypothesize that a cryptic rearrangement within the highly repetitive region of 21q11.1 is present in this family, disrupting pairing and leading to an increased risk of non-disjunction of chromosome 21 in this family.
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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 | 0.003 |
| Meta-epidemiology (narrow) | 0.002 | 0.002 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.003 | 0.001 |
| Science and technology studies | 0.003 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".