Not all monoallelic TP53 in MDS carries the same prognosis

Design

Retrospective analysis of two independent MDS cohorts with functional variant annotation

Population

4,505 patients with MDS (271 monoallelic, 499 multi-hit TP53)

Primary outcome

Leukaemia-free survival by TP53 allelic state, phenotype score and variant allele frequency

Effect

Monoallelic median 19.2 months; high vs low phenotype score 12.6 vs 43.3 months; high score + high VAF like multi-hit (9.2)

A single TP53 mutation on the report does not mean one thing. In myelodysplastic neoplasms, multi-hit TP53 is uniformly dismal, but the weight of a monoallelic (single-hit) mutation has been uncertain. This study of 4,505 patients across two cohorts applied a functional phenotype score, derived from saturation mutagenesis, to each monoallelic variant, alongside variant allele frequency.

Monoallelic TP53 sat between wild-type and multi-hit overall (median leukaemia-free survival 19.2 months, versus 37.2 for wild-type and 7.8 for multi-hit). But functional annotation split it sharply: a high phenotype score predicted far worse survival than a low score (12.6 versus 43.3 months). Combining the score with variant allele frequency was more striking still — monoallelic cases with a high score and burden behaved like multi-hit disease (9.2 months), while those with a low score and low burden behaved like wild-type (44.7 months).

For reporting, this argues that a monoallelic TP53 call is not self-interpreting. Where the data are available, functional annotation and variant allele frequency turn one ambiguous label into a meaningful prognostic statement — and the distinction matters most in cases that otherwise look low-risk by IPSS-R or IPSS-M.

• Monoallelic TP53 had intermediate leukaemia-free survival overall (19.2 months vs 37.2 wild-type and 7.8 multi-hit).
• A high phenotype score predicted much worse survival than a low score within monoallelic cases (12.6 vs 43.3 months).
• High score plus variant allele frequency ≥22% behaved like multi-hit disease (9.2 months); low score plus low burden behaved like wild-type (44.7 months).
• Where available, add functional annotation and variant allele frequency to a monoallelic TP53 result, especially in otherwise low-risk cases.

Why it matters

It changes a monoallelic TP53 result from a fixed label into a graded prognostic statement, reclassifying some apparently low-risk patients as high-risk.

Don't overread it

This is retrospective prognostic modelling using a published functional score; it refines risk estimates and does not by itself dictate a specific treatment.

The statistics, in plain English

Leukaemia-free survival is the time before progression to leukaemia or death. The point is that the same 'monoallelic TP53' label spanned 9 to 45 months depending on how damaging the specific variant was and how large its allele fraction — so the single label hides most of the information.

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