Definition of Translocation:
Translocation refers to a chromosomal abnormality where a piece of one chromosome breaks off and attaches to another chromosome. This rearrangement can lead to genetic disorders if it disrupts normal gene function or regulation.
Inheritance Pattern for Translocations:
The inheritance pattern can vary depending on whether it is balanced or unbalanced:
- Balanced Translocation:
- In this condition, there is no net gain or loss of genetic material.
- It usually does not cause any physical abnormalities or diseases in the individual who carries it.
- However, it can lead to reproductive issues such as infertility or an increased risk of producing offspring with genetic disorders if the offspring inherit an unbalanced form of the translocation.
- These are often not inherited in a straightforward Mendelian manner, but instead, they represent a chromosomal abnormality that may be carried through several generations without expression unless unbalanced gametes are produced.
- Unbalanced Translocation:
- It can results in a gain or loss of chromosomal material.
- This can lead to clinical symptoms and diseases such as congenital abnormalities or intellectual disabilities.
- These are typically inherited in a Mendelian pattern, with the abnormal chromosomal material being passed on to offspring.
Clinical Features of a Translocation Disorder:
Chronic Myelogenous Leukemia (CML) is an example . It is associated with the translocation t(9;22)(q34;q11), known as the Philadelphia chromosome. This involves the swapping of genetic material between chromosome 9 and chromosome 22, leading to the formation of a BCR-ABL fusion gene which causes uncontrolled cell division and promotes the development of leukemia.
Clinical Features of CML:
- Symptoms: Early symptoms may include fatigue, fever, weight loss, and frequent infections. As the disease progresses, individuals may experience symptoms like splenomegaly (enlarged spleen) and bone pain due to increased cell proliferation in the bone marrow.
- Diagnosis: CML is diagnosed through blood tests showing a high white blood cell count, and confirmed by cytogenetic analysis demonstrating the Philadelphia chromosome.
- Treatment: CML is typically treated with targeted therapies such as tyrosine kinase inhibitors (e.g., imatinib), which specifically inhibit the abnormal BCR-ABL protein activity. These treatments can lead to remission and improved survival rates.