Chromosomal Aberrations in Pernicious Anemia : Study of Three Cases before and after Therapy

Numerical and morphologic chromosomal aberrations were demonstrated in three cases of pernicious anemia in relapse. The morphological abnormalities including chromatid breaks, gaps and "giant" chromosomes were reduced in remission following vitamin B₁₂ therapy. The numerical changes consisted of aneuploidy (45 and 44 chromosomes) with the most common finding encountered (6 to 100 per cent of the cells) being monosomy involving the G 21 chromosome. This was present, not only in the marrow cells, but also in other tissues, e.g., peripheral blood and possibly skin fibroblasts, thus suggesting a more generalized disorder. The numerical anomalies persisted in remission. It is postulated that the structural anomalies, namely chromatid breaks, gaps, acentric fragments and "giant" chromosomes are related to vitamin B₁₂ deficiency and are correctable. The cause of the aneuploidy, since it was not correctable by treatment, is not clear. Since the patients were not studied before the disease had ensued, a congenital or acquired predisposition to megaloblastosis on the basis of G 21 monosomy cannot be excluded. The origin and significance of the extra chromatin material translocated onto the short arms of G 21 chromosomes in cases 1 and 3 remains unexplained.