Langerhans cell histiocytosis (LCH) is a disorder of unknown etiology that gives rise to clonal expansion of Langerhans-like cells or their precursors. The molecular basis include aberrant expression of several adhesion molecules and elevated expression of p53, c-myc, and H-ras. To identify new locations of LCH-related oncogenes or tumor-suppressor genes, we performed comparative genomic hybridization (CGH) and loss of heterozygosity (LOH) analysis on a series of 7 bone LCH lesions. Recurrent abnormalities were found by the CGH in all cases representing losses of DNA sequences on chromosomes 1p, 5, 6, 7, 9, 16, 17, and 22q. Gain of DNA copy number was seen on chromosomes 2q, 4q, and 12. The CGH data were supplemented by LOH analysis by means of 85 polymorphic microsatellite markers distributed along chromosomes 1, 7, 9, and 22. The highest frequency of LOH was found on 1p region in 3 of 7 informative cases and on chromosome 7 in 4 cases. Allelic loss was also detected on chromosomes 9 in 2 of 7 informative cases and on 22q in 1 of 7 cases. These results indicate that the deleted chromosomal segments may contain genes important in LCH initiation and progression.
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