A new approach to the study of the origin of genetic diseases: retroviral etiology of osteopetrosis.

The recent evidence of retroviral activity in a patient suffering from an atypical form of benign osteopetrosis suggests that it may represent the ancestral infectious form of a disease recognized until now only as a genetic disease. Therefore, making c-DNA probes from that virus should evidence retroviral-like sequences integrated in the genome of patients suffering from the inherited form of the disease. One of the goals of these investigations is to use these probes to map human "osteopetrosis" mutation(s) in the genome. A new approach is therefore defined for the study of these diseases, which although similar in their clinical manifestations, appear either as "sporadic" or "familial" cases: a retroviral etiology can account for this discrepancy. Another approach is also suggested for these kinds of disease, consisting of the search for retroviral sequences in a gene coding for an enzyme, when the main disease is associated with an apparently unrelated enzymatic deficiency. The insertion of retroviral sequence in a gene coding for an enzyme may result in both the disease and the inactivation of the gene. By comparing the genomic sequence of the enzyme in normal and pathological cases, the integrated retroviral gene(s) sequence will be available.