Mutagenic effects of isonicotinic acid hydracide in Fanconi's anemia.

Isonicotinic acid hydracide (INH) increases substantially the chromosomal instability in Fanconi's anemia (FA) cells. The same concentrations of INH do not significantly break chromosomes in heterozygous or normal cells. INH does not induce alkylation or cross-links in the DNA, like other mutagens known to increase breakage in FA cells. Possible mechanisms of the effect of INH are discussed. One consequence of this experiment is the possibility of an exact and doubtless prenatal diagnosis of a homozygous FA fetus.