Chromosome Analysis – Skin
88233, 88262, 88263, 88280, 88291
Culture / Microscopy / Karyotype
Container: Skin biopsies should be placed in sterile leak-proof containers with transport media.
If media is not available, place the specimen in sterile saline (e.g. Hanks Balanced Salt Solution).
Do not place in formalin.
Optimal Quantity: 1.0 cm2 or 2-3 punch biopsies
Storage: Room Temperature
Stability at Room Temperature: 8 hours, then refrigerate
Transportation: Avoid freezing or heating over 35OC
Final report in 14-28 days
A chromosome analysis on skin may be clinically significant to identify constitutional chromosome abnormalities observed in skin fibroblasts but not in peripheral blood lymphocytes (e.g. Pallister-Killian syndrome), to evaluate possible tissue-specific variation in patients with chromosomal abnormalities identified in peripheral blood lymphocytes and to confirm suspected mosaicismbased on skin pigmentation variation or a previous ambiguous karyotype.
Although mosaicism for chromosome abnormalities in lymphocyte cultures is common, apparent restriction of mosaicism to one tissue is unusual. After examination of lymphocyte karyotypes, certain patients warrant cytogenetic evaluation of a second tissue, usually cultured skin fibroblasts. Cytogenetic analysis from skin biopsies is indicated when there is a suspicion of mosaicism(e.g. in Pallister-Killian syndrome), or when the physician deems that skin sampling is preferable for clinical reasons.
Skin tissues are cultured to produce metaphase cells for G-banded chromosome analysis. Long term cultures are harvested at approximately 10-14 days, then G-banded. The fibroblast cells are studied at approximately 400 – 500 band level using 20 metaphases with complete analysis of 5 metaphase cells and 2 karyotypes.
Interpretation of Results
The morphologic interpretation and correlation of results on all cases is performed by a board-certified doctoral level scientist (laboratory director). The final report identifies the chromosomal sex and modal chromosome number. If abnormalities are present, they are explained in a paragraph which helps to clarify and correlate chromosomal findings with phenotype. Genetic counseling is recommended when chromosome aberrations, mosaic conditions, or unusual results are found, along with recommendation for further testing (e.g. microarray). References are included in the report to help the referring physician with interpretation, which include books or journals that contain appropriate information.