“…In these diseases, the mutations are unstable trinucleotide repeats that cause advancing disease in adults and can readily be detected presymptomatically. DNA diagnostic methods are available for some cancers, including retinoblastoma (9), adenoma polyposis coli (10), renal cancer (von Hippel-Lindau disease) (11), and also for adult polycystic kidney disease, which is the most common cause of heritable renal failure and whose risk can be determined genetically in advance of disease detection (12). Dedicated efforts to isolate the gene accounting for a form of breast cancer should broaden the presymptomatic diagnosis of cancer (13).…”