Why are microdeletions and microinsertions hard to diagnose in karyotyping?

Microdeletions and microinsertions are challenging to diagnose through karyotyping because these genetic alterations involve very small segments of DNA that may not be visible under a standard light microscope used in karyotyping. Traditional karyotyping typically focuses on analyzing larger chromosomal abnormalities, such as aneuploidies or large structural rearrangements. As a result, the subtle changes in chromosome structure caused by microdeletions and microinsertions often go undetected. Advanced techniques like fluorescence in situ hybridization (FISH) or array comparative genomic hybridization (aCGH) are usually required to identify these small-scale genetic variations.