Chromosome Analysis, High Resolution (Blood)

Clinical Information

This type of study is required for the detection of subtle chromosome rearrangements, and it is considered an important component in the diagnosis of microdeletion syndromes such as Prader-Willi syndrome, Angelman syndrome, Smith-Magenis syndrome, and Miller-Dieker syndrome.

Technical Information

High resolution chromosome analysis requires the use of elongation methods to obtain a high percentage of prophase and prometaphase spreads. The chromosomes are less condensed than in routine metaphase analysis, and the number of identifiable bands is expanded, allowing a more sensitive analysis of the karyotype.

For high resolution chromosome analysis a minimum of 20 cells are counted to determine the modal number and a minimum of 5 cells are analyzed for chromosomal abnormalities. Because special culture conditions are required, high resolution studies must be specifically requested.

Specimen Requirements

The accepted sample type is 3-4 ml of whole blood collected in a sodium heparin (green top) tube. For newborns and small infants, 2-3 ml of blood in a sodium heparin tube is acceptable. Blood kits are available by request.

Transport Instructions

Whole blood should be kept at room temperature and sent by courier or overnight mail to arrive at the laboratory the next day. Do not freeze or refrigerate the specimen.