1. SIMPLISTIC CLASSIFICATION OF LYMPHOID LEUKEMIAS
ACUTE LYMPHOID LEUKEMIA
PRECURSOR B-ALL
Specific molecular abnormalities
PRECURSOR T-ALL
BURKITT’S LEUKEMIA
CHRONIC LYMPHOID LEUKEMIAS
B-CLL
Other

2. FOR ALL INTENTS AND PURPOSES B-CLL DOES NOT OCCUR IN CHILDREN
Of about 5000 childhood leukemias
sent to my reference lab I have seen 2 cases
of B-CLL
Other chronic lymphoproliferative disorders are rare in children and are probably best discussed under lymphomas

3. ACUTE LYMPHOID LEUKEMIA Important entities
Precursor B-ALL
t(9;22) (BCR-ABL)
t(v;11) MLL
t(1;19) (E2A-PBX1)
t(12;21) (TEL-AML1)
Hyperdiploidy
?Hypodiploidy
Precursor T-ALL
SCL1(TAL)
HOX11
LMO1/2(RBTN1/2)
LYL1
?Primitive T-ALL

4. DIFFERENCES BETWEEN ADULT AND CHILDHOOD ALL T-ALL
No good data on frequency differences among genetically-defined groups
No good data that genetically-defined groups fare differently
Thus, for current purposes, T-ALL in adults and children are likely the same disease
Frequency of T-ALL higher in adults than children

5. DIFFERENCES BETWEEN GENETICS IN ADULT AND CHILDHOOD ALL PRECURSOR B-ALL

6. GENETICS AND PROGNOSIS IN CHILDHOOD ALL
GOOD PROGNOSIS
Hyperdiploidy
TEL-AML1
POOR PROGNOSIS
BCR-ABL
MLL
INTERMEDIATE PROGNOSIS
E2A-PBX1(if treated appropriately)
Other

7. CHILDHOOD VS ADULT ALL SUMMARY
Good prognosis genetic lesions in children rare in adults and should be considered distinct diseases
There are no significant differences between adult or childhood Burkitt’s leukemia, T-ALL, or leukemias with bcr-abl or MLL abnormalities, so that any protocols targeting these diseases should include both adults and children
Remaining 40% of childhood precursor B-ALL is not noticeably biologically different from adults, but still probably fare better