Station 9: Special Techniques

Additional tests may be necessary to aid in the diagnosis of specific conditions. The special techniques needed are listed below.

FISH

Molecular Cytogenetics - Fluorescent in situ hybridization (FISH)

FISH is the method of using fluorescent labeled DNA probes that hybridize to specific regions of the chromosomes. Depending on the probe used the analysis can be completed utilizing cells in metaphase or interphase. This technique requires the use of a fluorescent microscope . FISH is capable of identifying aneusomy, rearrangements, additions, and deletions of chromsomal material.

High Resolution Chromosome Analysis (725 bands or more)

A high resolution chromosome analysis is achieved by adding reagents at specific times during the harvest. By adding these reagents elongated chromosomes are obtained, allowing for more bands to be identified.

22q11 Deletion Syndrome (DiGeorge Syndrome, VeloCardioFacial Syndrome)

People with 22q deletion syndrome have a wide variety of clinical findings, including congenital heart disease (especially conotruncal malformations), palatal abnormalities including velopharyngeal incompetence and cleft palate, characteristic facial features, and learning disabilities. Hypocalcemia and immune problems may occur. Patients with this condition are at increased risk for development of psychiatric disorders in adolescence and early adulthood. More than 95% of patients with the clinical features of deletion 22q11 have a submicroscopic deletion of chromosome 22q11.

Abstracted from: Teebi A, Kennedy S, Chitayat D, Teshima I, Unger S, Babul-Hirji R, Shuman C, Weksberg R. Atlas of Pediatrics. Edited by Ronald Laxer, Ronald M. Laxer, Elizabeth Lee N. Ford-Jones, Jeremy N. Friedman, J. Ted Gerstle. ©2005 Current Medicine, Inc.