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Chromosome Analysis

Chromosome Analysis

Test Highlight

Chromosome Analysis

  

Clinical Use

  • Determine genetic cause for intellectual disability, congenital anomalies, infertility, miscarriage, stillbirth, and ambiguous genitalia

  • Confirm or exclude the diagnosis of known chromosomal syndromes

  • Diagnose and manage neoplastic conditions such as hematologic malignancies and solid tumors

Clinical Background

Chromosome analysis is the microscopic examination of chromosomes in dividing cells. Such analysis can detect changes in chromosomal number and structure. Deletions (eg, partial monosomy), duplications (eg, partial trisomy), and structural abnormalities such as translocations, inversions, and rings can be detected. These chromosomal changes may be associated with infertility, miscarriage, stillbirth, birth defects, intellectual disability, developmental delay, or abnormalities of sexual differentiation and development. Neoplasia may result from acquired tissue-specific cytogenetic aberrations in otherwise normal individuals.

Sensitivity of this conventional chromosome analysis method is best for larger chromosomal aberrations. Methods that utilize molecular probes (eg, fluorescence in situ hybridization [FISH]) may be required to detect smaller, subtler, changes. The advantage of chromosome analysis, however, is that specimens can be screened for multiple cytogenetic abnormalities, whereas most molecular methods require a suspicion or knowledge of the specific abnormality at the time of testing so that the appropriate probe(s) can be used.

Method

Cell culture is performed initially in order to stimulate mitosis. The cells are then harvested and stained to produce G-bands. Metaphase chromosomes are viewed microscopically at a resolution of 400-550 bands and aligned in a standard sequence based on size, centromere location, and banding pattern. Special stains such as C-banding, Q-banding, and Ag-NOR (silver) staining are used as needed to distinguish between normal variations and clinically significant abnormalities. B- or T-cell mitogens are used in cultures when indicated for diagnosing leukemia and lymphoma.

Interpretive Information

A patient-specific interpretive report is provided. The report includes chromosomal findings, clinical significance, and recommendations for additional studies (eg, FISH) when indicated.

 

Content reviewed 06/2013

 
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* The tests listed by specialist are a select group of tests offered. For a complete list of Quest Diagnostics tests, please refer to our Directory of Services.