Fragments of human chromosome 8 were introduced into cells derived from murine scid mice via X-irradiation and somatic cell fusion. The resulting hybrid clones contained human DNA fragment(s) which complemented the hyper-radiosensitivity of the scid cells. Alu-PCR products from these hybrids were used for chromosome painting using the technique of chromosome in situ suppression hybridization, allowing assignment of the human HYRC (hyper-radiosensitivity of murine scid mutation, complementing) gene, a candidate for a V(D)J recombinase gene, to human chromosome 8q11.