Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

CDKMS
60228
do not indicate a pathologic finding. Since CD8 RTE is a rare population, small changes in serial
measurements may result in some values being above the reference range; however, as noted, increases in
CD8 RTEs do not have clinical significance. In adults and most children, except infants and very young
children, decrease in CD8 RTEs are similarly unlikely to have any clinical significance since CD8 T cell
homeostasis in circulation is largely maintained by peripheral expansion of pre-existing CD8 T cells and
therefore, thymic output contributes minimally, if at all, to the maintenance of the CD8 T cell population.
Therefore, it is suggested that CD8 RTE only be ordered in conjunction with T-cell receptor excision
circles (TREC) and/or CD4 RTE in adults and older children. To evaluate immune reconstitution or
recovery of thymopoiesis post-T-cell depletion due to hematopoietic stem cell transplant, immunotherapy,
or other clinical conditions, it is essential to serially measure CD4, CD8 RTE, and TREC levels.
Reference Values:
CD8 ABSOLUTE
1 month-17 years: 143-902 cells/mcL
18-35 years: 208-938 cells/mcL
36-55 years: 142-844 cells/mcL
56-70 years: 58-680 cells/mcL
Reference values have not been established for patients that are 70 years of age.
CD8 RTE %
1 month-17 years: 0.1-1.7%
18-45 years: 0.0-0.6%
46-70 years: 0.0-0.3%
Reference values have not been established for patients that are 70 years of age.
CD8 RTE ABSOLUTE
1 month-17 years: 0.2-4.3 cells/mcL
18-25 years: 0.0-3.4 cells/mcL
26-50 years: 0.0-2.5 cells/mcL
51-70 years: 0.0-0.7 cells/mcL
Reference values have not been established for patients that are 70 years of age.
Clinical References: 1. Hassan J, Reen DJ: Human recent thymic emigrants--identification,
expansion, and survival characteristics. J Immunol 2001;167:1970-1976 2. McFarland RD, Douek DC,
Koup RA, et al: Identification of human recent thymic emigrant phenotype. Proc Natl Acad Sci
2000;97(8):4215-4220 3. Dong X, Hoeltzle MV, Abraham RS: Evaluation of CD4 and CD8 recent
thymic emigrants in healthy adults and children. Unpublished data 2008
CDKN1C Gene, Full Gene Analysis
Clinical Information: Beckwith-Wiedemann syndrome (BWS) is a disorder characterized by
prenatal and/or postnatal overgrowth, neonatal hypoglycemia, congenital malformations, and an
increased risk for embryonal tumors. Physical findings are variable and can include abdominal wall
defects, macroglossia, and hemihyperplasia. The predisposition for tumor development is associated
with specific tumor types such as adrenal carcinoma, nephroblastoma (Wilms tumor), hepatoblastoma,
and rhabdomyosarcoma. In infancy, BWS has a mortality rate of approximately 20%. Current data
suggest that the etiology of BWS is due to dysregulation of imprinted genes in the 11p15 region of
chromosome 11. Imprinting describes a difference in gene expression based on parent of origin. The
majority of autosomal genes exhibit biallelic (maternal and paternal) expression, whereas imprinted
genes normally express only 1 gene copy (either from the maternal or paternal allele). Imprinted genes
are usually regulated by methylation, which prevents the gene from being expressed. Loss of expression
or biallelic expression of an imprinted gene can lead to disease because of dosage imbalance. Some of
the imprinted genes located in the region of 11p15 include H19 (maternally expressed), LIT1 (official
symbol KCNQ1OT1; paternally expressed), IGF2 (paternally expressed), and CDKN1C (aliases p57
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