Table 1.
Characteristics of identical twin pairs.
| Twin Pair | Sex | Genetics | Twin A (age at dx) |
Twin B (age at dx) |
Pre-leukaemic cells in healthy co-twin (B) twin detected by: | Age of healthy co-twin at last follow up/screening* | Reference |
|---|---|---|---|---|---|---|---|
| 1 A/B | F | ETV6::RUNX1 | 2 y | N/A | FISH, IGH (DJ), Q-PCR, time course and Guthrie | 14 y 7 m | 23, 24, present study |
| 2 A/B | F | ETV6::RUNX1 | 3 y 9 m | N/A | FISH and Guthrie | 4 y | present study |
| 3 A/B | F | BCR::ABL1 | 5 y | N/A | FISH, Q-PCR, time course and Guthrie | 9 y 8 m | 18 |
| 4 A/B | F | RANBP2::ABL1 | 1 y 1 m | N/A | Q-PCR, time course and Guthrie | 3 y 5 m (ongoing) | present study |
| 5 A/B | M | High Hyperdiploid | 5 y | N/A | FISH, IGH (DJ), Q-PCR | 6 y 11 m | 26 |
| 6 A/B | F | KMT2A::AFF1 | 9 m | 10 m | Southern blot | 10 m | 11 |
| 7 A/B | F | ETV6::RUNX1 | 5 y 2 m | 13 y 11 m | PCR & sequencing | 5 y 2 m** | 8 |
| 8 A/B*** | M | KMT2A::MLLT10 | 3 y | N/A | PCR & sequencing | 3 y 3 m | 7 |
*Decision not to proceed with regular re-screening or to stop screening (pairs 1, 3 & 5) was taken by parents in consultation with their child’s clinician.
**Retrospective testing of sample taken from twin 7B at diagnosis of sibling: 5 yr 2 m.
***Case 8 A was AML. All other cases were B lineage ALL.