BRCA1 and neoplasm: Using four intragenetic markers (D11S2179 for ATM, D17S1322 and D17S1323 for BRCA1 and TP53 for TP53) and two adjacent markers (D11S1816 for ATM and D17S786 for TP53), our results showed that, after excluding noninformative tumours (six out of 74 at ATM, nine out of 74 at BRCA1 and 10/74 at TP53), the overall frequencies of LOH were 36.