Homozygous α0-thalassemia (Hb Barts) involving deletion of all the four loci of the alpha-globin genes (HBA2 and HBA1, genotype --/--) on chromosome 16 is usually lethal, ending up with hydrops fetalis and stillbirth due to the absence of the alpha-globin chain production. This evidence concerns the gene GSTM1 and hydrops fetalis.