Interpretive Handbook

Test 8425 :
Chromosome Analysis, Skin Biopsy

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.

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

Second-tier testing for chromosomal abnormalities


Follow-up testing when results from peripheral blood are inconclusive


Chromosomal analysis when a peripheral blood specimen is of poor quality or sampling is not possible

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



-Lack of viable cells

-Bacterial contamination

-Failure to transport tissue in an appropriate media

-Excessive transport time

-Exposure of the specimen to temperature extremes



-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.

46,XX or 46,XY. No apparent chromosome abnormality.

An interpretative report will be provided.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

Spurbeck JL, Carlson RO, Allen JE, Dewald GW: Culturing and robotic harvesting of bone marrow, lymph nodes, peripheral blood, fibroblasts, and solid tumors with in situ techniques. Cancer Genet Cytogenet 1988;32:59-66