Cytogenetic analysis is often performed on patients diagnosed with ALL. By completing a karyotype, an image of the chromosomes in the leukemic cells, the number and basic structure of the chromosomes can be assessed. The primary significance of cytogenetic analysis is prognosis and monitoring rather than a specific diagnosis. The karyotypes can vary widely among patients with ALL.
Our patient's cells exhibited a common aberration in childhood ALL, known as hyperdiploidy. Hyperdiploidy is defined as possessing more than 46 chromosomes, the number of chromosomes seen in normal cells. The image to the right is an example of a karyotype with ALL hyperdiploidy, where chromosomes 9, 14, 21, and X all have additional copies. (This is not an image from our patient's cells.)
Other abnormalities that can be seen in the cytogenetic analysis include specific translocations and rearrangements, which are also crucial for prognosis and treatment. The number of chromosomes and the rearrangements or translocations can then be assessed to place the patient in "risk groups." These include good or favorable risk groups and poor risk groups.
The patient had the following cytogenetic abnormalities:
Hyperdiploidy: 60 chromosomes
Translocation: t(12;21)(p13;q22)
Both of these changes place this patient in a favorable risk group. Unfavorable or high-risk groups include those with near haploidy or low diploidy and specific other translocations, including the Philadelphia Chromosome.
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