Test Catalog

Test ID: CHRTI    
Chromosome Analysis, Skin Biopsy

Useful For Suggests clinical disorders or settings where the test may be helpful

Diagnosis of mosaic congenital chromosome abnormalities, including mosaic aneuploidy and mosaic structural abnormalities


Subsequent chromosome analysis when results from peripheral blood are inconclusive

Testing Algorithm Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test includes a charge for cell culture of fresh specimens and professional interpretation of results. Analysis charges will be incurred for total work performed, and generally include 2 banded karyograms and the analysis of 20 metaphase cells. If no metaphase cells are available for analysis, no analysis charges will be incurred. If additional analysis work is required, additional charges may be incurred.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Chromosomal abnormalities cause a wide range of disorders associated with birth defects and congenital diseases. Usually, the abnormalities can be demonstrated in peripheral blood, which is readily available. Chromosome analysis on skin fibroblasts may be indicated when the results from peripheral blood are inconclusive or in clinical circumstances such as suspected cases of chromosome mosaicism, confirmation of new chromosome disorders, or some dermatological disorders.


Subtle structural chromosomal anomalies can occasionally be missed.


Chromosomal mosaicism may be missed due to statistical sampling error (rare).

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretative report will be provided.

Interpretation Provides information to assist in interpretation of the test results

When interpreting results, the following factors need to be considered:

-Some chromosome abnormalities are balanced (no apparent gain or loss of genetic material) and may not be associated with birth defects. However, balanced abnormalities often cause infertility and, when inherited in an unbalanced fashion, may result in birth defects in the offspring.

-A normal karyotype (46,XX or 46,XY with no apparent chromosome abnormality) does not eliminate the possibility of birth defects such as those caused by submicroscopic cytogenetic abnormalities, molecular mutations, and environmental factors (ie, teratogen exposure).


It is recommended that a qualified professional in Medical Genetics communicate all results to the patient.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Interfering factors:

-Transport time should not exceed 2 days.

-Inadequate amount of fluid may not permit adequate analysis.

-Improper packaging may result in broken, leaky, and contaminated specimen during transport.

-Exposure of the specimen to temperature extremes (freezing or > 30 degrees C) may kill cells and interfere with attempts to culture cells.

Clinical Reference Recommendations for in-depth reading of a clinical nature

1. The Principals of Clinical Cytogenetics. Second edition. Edited by SL Gerson, MB Keagle. Totowa, NJ, Humana Press 2005 pp 210

2. Azcona C, Bareille P, Stanhop R: Lesson of the week: Turner's syndrome mosaicisim in patients with a normal blood lymphocyte karyotype. BMJ 1999;318:856-857

3. Woods CG, Bankier A, Curry J, et al: Asymmetry and skin pigmentary anomalies in chromosome mosaicism. J Med Genet 1994;31:694-701

4. Ribeiro Noce T, de Pina-Neto JM, Happle R: Phylloid pattern of pigmentary disturbance in a case of complex mosaicism. Am J Med Genet 2001;98:145-147

Special Instructions Library of PDFs including pertinent information and forms related to the test