Cytogenetics
This is usually driven by an acquired cytogenetic abnormality in a stem cell line, a t(9;22) that forms a BCR-ABL fusion gene with tyrosine kinase activation.
What our notes say
- This is usually driven by an acquired cytogenetic abnormality in a stem cell line, a t(9;22) that forms a BCR-ABL fusion gene with tyrosine kinase activation. (hematopathology — Past Paper Questions & Answers)
- Cytogenetic (chromosomal) abnormalities are broadly divided into numerical and structural abnormalities, and may affect either autosomes or sex chromosomes. (Genetic Disorders CAT: Key Terms & Inheritance Patterns Explained)
- This is precursor B-cell ALL (CD19+, CD10+, TdT+) with hyperdiploidy, one of the best-recognised favourable cytogenetic subgroups in paediatric ALL, associated with excellent (>90%) cure rates. (Haematopathology MCQs: Blood Disorders & Anemia Explained)
- Confirmatory tests: bone marrow aspirate/biopsy, flow cytometry, cytogenetics (Pathology Practical Revision Guide)
- Biopsy shows a monotonous pattern of small non-cleaved lymphocytes; cytogenetics show t(8;14). (Hematology MCQs)
- a) Bone marrow aspirate and trephine biopsy with cytogenetic analysis (HEMATOLOGY EOY 2025 — Past Paper Questions & Answers)
Study material on Cytogenetics
- Haematology Exam 2025: MCQs on Anaemia, Leukaemia & Clotting
- Haematology End of Year 2025 Past Paper — MKU MBML 3200 Questions & Answers
- Acute Leukaemia (AML/ALL) & WBC Disorders: Hematology Guide
- Haematopathology MCQs: Blood Disorders & Anemia Explained
- HEMATOLOGY EOY 2025
- pathology essays
- systemic pathology essays
- Genetic Disorders CAT: Key Terms & Inheritance Patterns Explained
- Hematologic Malignancies and Bleeding Disorders
- Weekly Year 2: Molecular Genetics and Cytogenetics Exam - July 17, 2026 (Section A: MCQs)
- COMPLEX MULTIGENIC AND CYTOGENETIC DISORDERS - 50 MCQs
- Complex Multigenic and Cytogenetic Disorders MCQs
- Weekly Year 2: Molecular Genetics and Cytogenetics Exam - July 3, 2026 (Sections B & C)
- Weekly Year 2: Molecular Genetics and Cytogenetics Exam - July 3, 2026 (Section A: MCQs)
- Weekly Year 2: Molecular Genetics and Cytogenetics Exam - July 17, 2026 (Sections B & C)
Practice questions on Cytogenetics
A 45-year-old woman develops chronic myeloid leukemia (CML). Cytogenetic analysis reveals a reciprocal translocation between chromosomes 9 and 22. The resultant fusion gene codes for a protein with which abnormal activity?
- Constitutively active tyrosine kinase
- Inhibited serine/threonine kinase
- Actively degrades DNA
- Stimulates apoptosis
Answer: A. The t(9;22) translocation in CML creates the Philadelphia chromosome, resulting in the BCR-ABL fusion gene. This fusion gene encodes a constitutively active tyrosine kinase that drives uncontrolled cell proliferation.
A 45-year-old woman has chronic myeloid leukemia (CML). Cytogenetic analysis reveals a reciprocal translocation between chromosomes 9 and 22. The resultant fusion gene codes for a protein with which abnormal activity?
- Constitutive tyrosine kinase activity
- Inhibition of cell cycle progression
- Impaired DNA repair
- Activation of apoptosis
Answer: A. The t(9;22) translocation creates the Philadelphia chromosome, leading to the formation of the BCR-ABL fusion gene. This gene product is a constitutively active tyrosine kinase that drives the uncontrolled proliferation of myeloid cells in CML.
A 45-year-old woman develops chronic myeloid leukemia (CML). Cytogenetic analysis reveals a reciprocal translocation between chromosomes 9 and 22. The resultant fusion gene codes for a protein with which abnormal activity?
- Inhibition of DNA repair
- Constitutive tyrosine kinase activity
- Inhibition of apoptosis
- Abnormal cell cycle regulation
Answer: B. The t(9;22) translocation in CML creates the Philadelphia chromosome, which results in the BCR-ABL fusion gene. This gene product is a constitutively active tyrosine kinase, leading to uncontrolled proliferation of myeloid cells.
A 45-year-old woman develops chronic myeloid leukemia (CML). Cytogenetic analysis reveals a reciprocal translocation between chromosomes 9 and 22. The resultant fusion gene codes for a protein with which abnormal activity?
- Inhibition of tyrosine kinase activity
- Constitutive activation of tyrosine kinase activity
- Inhibition of serine/threonine kinase activity
- Constitutive activation of serine/threonine kinase activity
Answer: B. The translocation between chromosomes 9 and 22 creates the Philadelphia chromosome, resulting in the BCR-ABL fusion gene. This fusion gene encodes a constitutively active tyrosine kinase, which drives the uncontrolled proliferation of myeloid cells seen in CML.
A 45-year-old woman develops chronic myeloid leukemia (CML). Cytogenetic analysis reveals a reciprocal translocation between chromosomes 9 and 22. The resultant fusion gene codes for a protein with which abnormal activity?
- Constitutive tyrosine kinase activity
- Impaired DNA repair
- Inactivated tumor suppressor function
- Enhanced cell adhesion
Answer: A. The t(9;22) translocation creates the BCR-ABL fusion gene (Philadelphia chromosome), which encodes a constitutively active tyrosine kinase. This unregulated kinase activity drives uncontrolled proliferation of myeloid cells, characteristic of CML.
A 72-year-old man has progressive fatigue over 2 years. Bone marrow biopsy shows hypercellularity with dysplastic megakaryocytes, erythroid hyperplasia, and 6% blasts. Cytogenetics shows deletion of chromosome 5q. Most likely prognosis?
- Very poor — likely transforms to AML within weeks
- Good — 5q deletion is associated with favorable prognosis in MDS
- Intermediate — requires immediate bone marrow transplant
- Poor — 5q deletion always indicates secondary AML
Answer: B. Isolated 5q deletion in MDS (5q- syndrome) is associated with a favorable prognosis, macrocytic anemia, low blast count, and good response to lenalidomide. It is one of the best prognostic cytogenetic findings in MDS. ---