In an earlier study of dimethylnitrosamine-induced HF in rats (Ala-Kokko et al., 1987), the mRNA concentrations of type I, III, and IV collagen increased in the early stage of HF, but the increase of type IV collagen was particularly significant in the early stage of fibrosis, and the accumulation of type I and III collagen was mainly concentrated in the late stage of fibrosis. This evidence concerns the gene SGCG and hydrops fetalis.