No infant or childhood KMT2A-rearranged cohort has REPORTED IDH status — and at least one has certainly MEASURED it
also called IDH status in infant KMT2A-rearranged leukaemia · measured but not reported
A co-mutation that changes DNA methylation is more common in adult leukaemias driven by this fusion, and that could matter for how the fusion finds its targets. Nobody has published that number for infants. But a 2025 study sequenced the whole genomes of 36 infants and children with this exact disease, so the answer is almost certainly already sitting in its supplementary tables — it has been measured and not reported.
The same thing, for a scientist
The methylome argument for this project turns on IDH status in the index disease: IDH2 is enriched in KMT2A-rearranged AML (16.0% vs 10.4%, p = 0.0004 recomputed) and 2-HG inhibits TET, raising CpG methylation at an address the fusion reads unmethylated. **Bounded 2026-09-21 with query translations recorded: no title/abstract reports IDH status in an infant or paediatric KMT2A-rearranged cohort.** 4 candidate records screened, 0 on topic. **But this is an absence of REPORTING, not of measurement**: PMID 41062506 (Nat Commun 2025) performed whole-genome and whole-exome sequencing on 36 infants and children with relapsed KMT2A-r ALL/AML plus 257 longitudinal samples, and its abstract does not mention IDH, TET2, DNMT3A or methylation at all. WGS/WES calls IDH1 and IDH2 as a matter of course. The dataset is open access (PMC12508131).
The distinction that makes this worth an entry
| absence class | measured-not-reported |
|---|---|
| bounded on | 2026-09-21, PubMed E-utilities esearch, title/abstract only |
| shown for fusion | NOT APPLICABLE as a localisation question. As a cohort question the answer is the point of this entry: the index disease has never had its IDH status reported, in any cohort, at any age. |
| absence class previous freetext | reported-but-not-measured is FALSE here; this is MEASURED-BUT-NOT-REPORTED |
| absence class basis | PMID 41062506 performed WGS/WES on 36 infants and children with KMT2A-r disease; WGS calls IDH1/IDH2 as a matter of course. Open access at PMC12508131. |
| absence class assigned | 2026-09-21 (cycle 47, king) |
queries with translations — the numbers behind the chart
[
{
"query": "IDH1[tiab] OR IDH2[tiab]",
"count": 7257,
"translation": "\"IDH1\"[Title/Abstract] OR \"IDH2\"[Title/Abstract]",
"role": "operand control"
},
{
"query": "KMT2A[tiab] OR MLL[tiab] OR \"t(4;11)\"[tiab]",
"count": 8162,
"translation": "\"KMT2A\"[Title/Abstract] OR \"MLL\"[Title/Abstract] OR \"t 4 11\"[Title/Abstract]",
"role": "operand control"
},
{
"query": "(IDH1[tiab] OR IDH2[tiab]) AND (KMT2A[tiab] OR \"MLL-rearranged\"[tiab])",
"count": 48,
"translation": "(\"IDH1\"[Title/Abstract] OR \"IDH2\"[Title/Abstract]) AND (\"KMT2A\"[Title/Abstract] OR \"MLL-rearranged\"[Title/Abstract])"
},
{
"query": "(IDH1[tiab] OR IDH2[tiab]) AND (KMT2A[tiab] OR \"MLL-rearranged\"[tiab]) AND (infant[tiab] OR pediatric[tiab] OR paediatric[tiab] OR child[tiab])",
"count": 2,
"translation": "all three groups resolved to [Title/Abstract]"
},
{
"query": "(IDH1[tiab] OR IDH2[tiab]) AND \"t(4;11)\"[tiab]",
"count": 2,
"translation": "(\"IDH1\"[Title/Abstract] OR \"IDH2\"[Title/Abstract]) AND \"t 4 11\"[Title/Abstract]"
}
]screened
{
"distinct_records": 4,
"on_topic": 0,
"rejections": {
"28076841": "therapy-related myeloid neoplasms, 14 adult patients — not an infant KMT2A-r cohort",
"37046645": "venetoclax experience in 43 paediatric AML patients — paediatric, but not IDH-stratified by KMT2A status",
"40133836": "transcriptomic comparison of t(9;11) AML CELL LINES — not a patient cohort; IDH1/2 appears only in a list of epigenetic regulators",
"41477275": "MPAL review — a review, not a cohort"
}
}the dataset that would close it
{
"pmid": "41062506",
"what": "WGS and WES of 36 infants and children with relapsed KMT2A-r ALL/AML, plus longitudinal deep sequencing of 257 samples in 30 patients",
"why_it_settles_it": "whole-genome and whole-exome sequencing call IDH1 and IDH2 as a matter of course; the variants are in the data whether or not the paper discusses them",
"access": "open access, PMC12508131",
"abstract_mentions_IDH": false,
"abstract_mentions_TET2_DNMT3A_or_methylation": false
}- This entry describes a gap in reporting and supports no clinical action. IDH inhibitors are approved in adult AML and nothing here suggests using one in an infant — there is no reported IDH frequency in this population at all, which is the point.
- If anyone reads the adult 16% enrichment as a rationale for IDH testing in infant KMT2A-rearranged leukaemia, note that the adult arm is 43% KMT2A-PTD, a different lesion from the fusion this project studies.
- Open PMC12508131's supplementary tables and read the IDH1/IDH2 calls for all 36 patients. That is an afternoon, needs no new patient and no wet work, and it is the single cheapest way to test whether the methylome argument has any purchase in the index disease.
- If the infant frequency is zero or near-zero, the adult IDH2 enrichment does not transfer, and the hypermethylating-co-mutation route to challenging the CXXC address closes for this disease specifically.
- The adult comparison is itself confounded: 43.1% of that KMT2A-rearranged arm is KMT2A-PTD rather than a fusion, and the table is not stratified. The infant cohort has no PTD, so it is also the cleaner test.
- E1moderate confidence 3 of 5: One strong study, or several smaller consistent ones.database
Bounded absence. Searching title and abstract on 2026-09-21, IDH1 or IDH2 co-occurs with KMT2A or MLL-rearranged in 48 records; adding an infant or paediatric term reduces that to 2, and IDH with t(4;11) returns 2. Across the 4 distinct records, NONE reports IDH mutation status in an infant or paediatric KMT2A-rearranged cohort: one is adult therapy-related myeloid neoplasia, one is a paediatric venetoclax series not stratified by KMT2A, one is a cell-line transcriptomic study, and one is a review. Operand controls pass at 7,257 and 8,162, so the query reaches the literature.
Bounded absence, PubMed E-utilities esearch, 2026-09-21: IDH status in infant/paediatric KMT2A-rearranged cohorts. Query translations recorded in data.queries_with_translations; all resolved to [Title/Abstract] and the cytogenetic term was quoted per rule 95. · PubMed (bounded query; counts, translations and screening decisions recorded) 2026What this evidence cannot show
Title and abstract only. Supplementary tables, which is exactly where a cohort's per-patient mutation calls live, were NOT searched — and that is the limitation that makes the next item necessary rather than optional. Rule 94 and rule 95 were both applied: every group is tagged per-term and the translocation is quoted; the recorded translations show [Title/Abstract] throughout and "t 4 11" rather than a UID filter.
Evidence that argues against this (1)
- A title/abstract search cannot see a supplementary table, and co-mutation frequencies are routinely reported there rather than in the abstract. So this bound establishes that nobody has FEATURED the result, which is weaker than nobody having obtained it — and the next evidence item shows the distinction is not hypothetical. Ahlgren L et al. 2025
- E2moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper
THE MEASUREMENT ALMOST CERTAINLY EXISTS AND IS UNREPORTED. Whole-genome and whole-exome sequencing was performed on 36 infants and children with relapsed KMT2A-rearranged ALL and AML, with longitudinal deep sequencing of 257 samples across 30 patients. The abstract reports somatic alterations in drug-response genes, most commonly TP53 and IKZF1 at 64%, and a chemotherapy-exposure mutational signature. It does not mention IDH, IDH1, IDH2, TET2, DNMT3A or methylation anywhere. Exome and genome sequencing call IDH1 and IDH2 routinely, so the genotypes are in the data regardless of whether the text discusses them.
The genomic landscape of relapsed infant and childhood KMT2A-rearranged acute leukemia. · Ahlgren L, Pilheden M, Sturesson H, Song G, Walsh MP, Yang M · Nat Commun 2025What this evidence cannot show
Abstract fetched and read 2026-09-21; the full text and supplementary tables were NOT retrieved, so it is not established here that IDH calls are present in them — only that WGS/WES generates them and that the abstract is silent. The cohort is RELAPSED disease, which is a selected population and may not carry diagnosis-time co-mutation frequencies. n = 36 is small for a co-mutation occurring at roughly 10-16% in adults, so even a complete report would have wide intervals.
Evidence that argues against this (1)
- Asserting that the data exists because the assay generates it is an inference, not an observation. Variant calls can be filtered out before deposition, panels can be restricted, and a relapsed-disease cohort of 36 could plausibly contain zero IDH mutations and be reported as uninformative rather than omitted. The honest claim is that the supplement is the cheapest place to look, not that the answer is certainly there. PubMed (bounded query) 2026
Generalises the distinction that entry drew. It closed by asking how many absences recorded as 'nobody has looked' are actually 'nobody has published the cross-tabulation'; the sweep answers that 24 of 26 never asked, naming no deposited accession at all.
THE GAP UNDER THE ENRICHMENT. gene-idh2 records IDH2 mutation at 16.0% in KMT2A-rearranged AML against 10.4% elsewhere, recomputed at OR 1.630, p = 4.1e-4. That figure is adult, and 43.1% of its KMT2A-rearranged arm is KMT2A-PTD rather than a fusion. No infant or paediatric KMT2A-rearranged cohort has ever REPORTED an IDH frequency, so the number this project reasons from has never been measured in the disease this project is about.
AND IDH1 IS THE CONTROL THAT MAKES THE GAP MATTER. IDH1 is flat in the same adult assay (6.7% vs 7.6%, p = 0.53) while IDH2 is enriched - same oncometabolite, same mechanism, opposite result. A discrepancy that sharp between two genes doing the same thing is exactly the kind that can be an artefact of cohort composition, and the infant data that would test it exists unreported.
THE HYPOTHESIS CANNOT CURRENTLY BE TESTED IN THE INDEX DISEASE, and this entry says why in one sentence: the co-mutation frequency it turns on has never been reported in an infant KMT2A-rearranged cohort. If the infant frequency is near zero, the hypermethylating route to challenging the CXXC address closes for this disease whatever the adult numbers say. The test costs an afternoon with an open-access supplementary table.
CONFIRMED BY READING: the named cohort paper's 96,537-character full text contains IDH1, IDH2, TET2 and DNMT3A zero times each