Description

This test evaluates chromosomal number and structure using a peripheral blood specimen. It provides a visual analysis of chromosomes to detect large-scale chromosomal abnormalities.

Overview

Chromosome analysis (karyotype) examines the number and structure of chromosomes under microscopy.

It is commonly used as a first-line genetic test when chromosomal abnormalities are suspected.

This test identifies major chromosomal changes but does not detect very small genomic alterations that require microarray testing.

What This Test Can Detect

A standard karyotype may identify:

  • Extra or missing chromosomes (aneuploidy)
  • Large deletions or duplications
  • Structural rearrangements (translocations, inversions)
  • Marker chromosomes
  • Mosaic chromosomal patterns (moderate levels)

Does this test detect Down syndrome?

Yes. Chromosome analysis (karyotype) can identify Trisomy 21, the chromosomal pattern associated with Down syndrome.

This test can detect:

  • Full Down syndrome
  • Translocation Down syndrome
  • Some cases of mosaic Down syndrome

Karyotype analysis is commonly used as a diagnostic test when Down syndrome is suspected.

If mosaic Down syndrome is a concern, additional or higher-resolution testing may be considered.

Common Clinical Uses

This test is often selected in the evaluation of:

  • Suspected chromosomal abnormalities
  • Mosaic chromosome screening
  • Developmental delay or congenital anomalies
  • Infertility evaluation
  • Recurrent pregnancy loss
  • Abnormal prenatal or screening results (postnatal follow-up)

Clinical Notes

Karyotype analysis evaluates chromosome structure at a microscopic level and is useful for identifying large chromosomal changes and structural rearrangements.

If higher resolution analysis is needed, chromosomal microarray testing may be considered separately.

Fasting: Not required