IDENTIFICATION OF 2 COMPLEMENTATION GROUPS IN FANCONI ANEMIA

Considerable variation can be observed in the clinical presentation of Fanconi anemia (FA) patients and in the degree of sensitivity of their cells to DNA damaging agents. The hypothesis that genetic heterogeneity underlies this variation was examined by testing for complementation in somatic cell hybrids constructed from FA cells. Hybrids were formed by fusing lymphoblastoid cell lines derived from 4 different FA patients. Complementation of the cellular defects in FA was tested by examining sensitivity to growth inhibition by mitomycin C(MMC), spontaneous chromosome breakage, and MMC-induced chromosome breakage in the hybrid cells. These studies revealed the presence of at least 2 complementation groups, suggesting that there may be 2 or more different FA genes.