Category Archives: Genetic Disorders Info

Acute Lymphocytic Leukemia (ALL) Info

t(1;19)(q21 or 23;p13)
The t(1;19) or the der(19) from the t(1;19) rearrangement is almost exclusively observed in pre-B cell acute lymphocytic leukemia (ALL) with FAB-L1 morphology.  The t(1;19) ALL does not usually show extreme leukocytosis and suggests a relatively poor patient prognosis.

t(4;11)(q21;q23)
The t(4;11) is almost exclusively observed in early B-cell acute lymphocytic leukemia (ALL-L2).  Most patients with the t(4;11) ALL are less than two years old and present with  an extremely elevated white blood cell count along with a high percentage of blasts and hepatospenomegaly.  It is not uncommon for the t(4;11) ALL to show a biphenotypic immunologic presentation and to develop additional chromosome abnormalities as the disease progresses or during relapse.  The prognosis of t(4;11) ALL patients has been reported to be poor.

del (6q)(multiple breakpoint)
Deletion of the chromosome 6 long arm (6q-) is almost exclusively observed in lymphoid disease, including non-Hodgkin’s lymphoma.  The 6q- is rarely observed in Hodgkin’s disease.  The 6q- is usually accompanied by other chromosome changes and has been reported to indicate a relatively poor patient prognosis.

del(9)(p21 or 22)
Loss of material from the chromosome short arm (9p-) or rearrangements involving the 9 short arm has been most frequently observed in T-cell “lymphomatous” acute lymphocytic leukemia (ALL).  Patients usually present with elevated white blood cell counts and enlargement of  lymph nodes and spleen.  del(9) patients have also been reported to have a relatively poor patient prognosis and frequently exhibit CNS involvement.

t(9;22)(q34;q11 or 12)
When found in ALL, the t(9;22) indicates an extremely poor patient prognosis, particularly if accompanied by monosomy 7.

Hyperdiploidy with 50+ chromosomes
The presence of 50+ chromosomes without chromosome rearrangements or other clinically significant chromosome changes (e.g. 5q- or -7), is usually observed in acute lymphocytic leukemia (ALL) and frequently present in young patients, ages 3-5 years old.  Hyperdiploidy of this type has been reported to suggest a relatively poor patient prognosis.  The presence of chromosome rearrangements generally suggests a prognosis relative to the type of rearrangement.

Near-haploidy with 26-29 chromosomes
Near-haploidy is a relatively rare and possibly under-reported finding usually observed in early B-cell acute lymphoblastic leukemia (ALL-L2) in children under the age of 17 years.  Near-haploidy is frequently associated with extremely poor prognosis.

Acute Myeloid Leukemia (AML:M2) Info

t(8;21)(q22;q22)
The t(8;21) rearrangement is almost exclusively observed in acute nonlymphocytic leukemia (ANLL) and specifically in acute myloid leukemia (AML:FAB M2).  The t(8;21) is also associated with a large number of cells showing auer rods.  Additional chromosome changes are observed in over 75 percent of t(8;21) cases which also include the loss of a sex chromosome, a deleted 9q, trisomy 8, and monosomy 7.  The presence of the t(8;21) alone has been reported to indicate a relatively good patient  prognosis.

Acute Myelomonocytic Leukemia (AMMoL:M4eo) Info

Inv(16)(p13q22)
Inversions of chromosome 16 and rearrangements involving band 16q22 are almost exclusively observed in acute nonlymphocytic leukemia, specifically acute myelomonocytic leukemia (AMMoL:FAB-M4eo). This chromosome abnormality is associated with increased numbers of immature eosinophils in the bone marrow and peripheral blood. Eosinophils may show some nuclear hypo-segmentation and positive PAS/PE staining. These patients have been reported to frequently develop CNS leukemia. The inversion of chromosome 16 or a band 16q22 abnormality is reported to be suggestive of a relatively good patient prognosis.

Acute Non – Lymphocytic Leukemia (ANLL)- GeneralMyeloproliferative / Myelodysplastic Disease Info

Inv(3)(q21q26),dup(3q),t(3q;3q)
Rearrangements of the chromosome 3 long arm, particularly in the q21/q26 band region, have been observed in acute nonlymphocytic leukemia (ANLL), chronic myelocytic leukemia(CML) and myelodysplastic syndromes. Thrombocytosis and abnormal megakaryocytopoiesis with the presence of micromegakaryocytes and hypolobulated nuclei are most often observed.

-5 or del(5)(q12q33)
The loss of chromosome 5, or the deletion of the chromosome 5 long arm (5q-) is most exclusively observed in acute nonlymphocytic leukemia (ANLL), preleukemia, myeloproliferative and myelodysplastic disease. The 5Q- has been reported to be associated with hematopoietic disease secondary to mutagenic exposure. The 5q- is often associated with an aggressive disease state and with a poor patient prognosis.

-7 or del(7)(q22)
The loss of chromosome 7 or the chromosome 7 long arm (7q-) is usually observed in acute nonlymphocytic leukemia (ANLL), myeloproliferative and myelodysplastic disorders and occasionally in acute lymphocytic leukemia (ALL). Monosomy 7 and del(7) have been reported to be associated with an aggressive disease state and with a poor patient prognosis.

+8
Trisomy of chromosome 8 is almost exclusively observed in acute nonlymphocytic leukemia (ANLL:FAB-M2, M4 and M5), as a secondary chromosome change in chronic myelocytic leukemia (CML), and in myeloproliferative and myelodysplastic disease. Trisomy 8 is only rarely observed in lymphoid disease. As a secondary chromosome change in CML, trisomy 8 is often associated with cells in a blastic phase and associated with a relatively poor patient prognosis.

+9
Trisomy or chromosome 9 has been most frequently observed in a wide variety of myeloid hematopoietic disease including acute nonlymphocytic leukemia (ANLL) and myelodysplastic syndromes, specifically myelofibrosis and polycythemia vera. Trisomy 9 is usually associated with other chromosome changes.

Del(11)(q23) or t(11;-)(q23;-)
Deletions of the 11q23 band region and rearrangements of this region with other chromosomes, specifically the t(9;11) rearrangement, are most frequently observed in acute nonlymphocytic leukemia (ANLL). These changes are almost exclusively associated with acute monocytic leukemia (AMoL:FAB-M5a). Exceptions include the t(4;11)(q21;q23) and t(11;14)(q23;q32) which are observed in acute lymphocytic leukemia. More specifically, the t(4;11) is frequently observed in biphenotypic ALL with monocytoid involvement. The myeloid 11q23 rearrangements are found most frequently in infants and young patients.

Del(13)(q12 or q14)
Deletions of the chromosome 13 long arm, particularly involving band 13q14 have been observed in a variety of neoplastic and pre-neoplastic disease. This deletion is most frequently observed in retinoblastoma, myeloproliferative and myelodysplastic disease as well as myelofibrosis.

Acute Promyelocytic Leukemia (APL:M3) Info

t(15;17)(q22;q21 or12)
This translocation is a remarkably specific marker for acute promyelocytic leukemia (ANLL-M3).  This strong association is further exemplified by the fact that occasionally this translocation develops as a secondary aberration during CML blast transformation, with patients exhibiting disease characteristics indistinguishable from APL. Apart from these exceptional CML blast crisis patients, t(15;17) has not been detected in any malignancies other than ANLL-M3.  t(15;17) APL patients usually exhibit disseminated intravascular coagulation (DIC) and hyper- or micro-granulated promyelocytes.