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Genetics: Human Aspects

The third section deals with the isolation and characterisation of repair deficient mutants in Drosophila (Smith et al), the effect of meiotic and repair mutants on chromosome behaviour (Baker et al), the biochemistry of some repair mutants (Boyd et al), and the induction of mutations in repair mutants (Wurgler and Graf). All this is summarised and put into perspective by Green. Section IV, presumably the most relevant to the readers of the Journal ofMedical Genetics, comprises eight contributions plus a summary chapter by Wolff. The section begins with a discussion of the role ofDNA lesions and their repair in the production of chromosomal aberrations (Bender), followed by one on the relationship between DNA repair, chromosomal aberrations, and the potentially lethal damage caused by x-rays (Fornace et al). Further discussion ofDNA repair in relation to chromosome aberrations (including the production of sister chromatid exchanges) is provided by Sasaki, while McCormick and Maher report on the repair systems which modify the yield of mutations in human cells in culture. Trosko et al then describe attempts both to use resistance to diptheria toxin as a marker for mutagenesis in cultured mammalian cells and to isolate DNA repair deficient Chinese hamster cell lines. This is followed by three brief reports: one on induction of mutation by ultraviolet radiations (UVR) in a UVR sensitive variant of the L5178Y mouse lymphoma cell line (Sato), one on the DNA replication and pyrimidine dimer excision in human fibroblasts receiving single or split doses of UVR (Waters), and one on the inhibition by aphidicolin of the DNA synthesis of isolated nuclei (Bertazzoni et al). The section on mouse germ cells contains papers on the unscheduled DNA synthesis of male (Sega) and female (Pedersen and Brandriff) germ cells. Generoso reports on the effect of repair processes, in the fertilised eggs, on the yield of dominant lethal mutations and chromosome translocations induced by exposure of male postmeiotic germ cells to chemical mutagens, and Russel contributes the summary paper. The final section comprises a chapter by German on the human chromosomal instability syndromes and a brief note by Langley on DNA repair and assessment of risks to the human population. This volume covers a lot of ground and cannot be Book reviews