Chromosome 13ql4 deletion is one of the most common cytogenetic abnormalities in multiple myeloma (MM). LSI( locus-specific identification)-RBI (13ql4.1 - 14.2 region)and LSI-D13S319( 13ql4. 3 region) probes are usually used to detect 13ql4 deletion. The aims of this study was to compare the incidence of chromosome 13ql4. 1 -14.2 and 13ql4. 3 deletion and to detect 13ql4 deletion size and number of involved cells in MM patients. The chromosome 13ql4 region was detected by fluorescence in situ hybridization using probes LSI-RBI and LSI-D13S319 in plasma cells of 112 MM patients. The results showed that 47. 3% (53 out of 112) MM patients had both LS1-RB1 and LSI-D13S319 13ql4 deletion (cut-off value: 7% ) , and the deletion rates detected by probes LSI-RBI and LSI-D13S319 were accordant. The positive rates of 13ql4 deletion were 46. 4% and 47. 3% respectively when the cut-off level was increased to 20% , and the corresponding rate was 98%. MM patients carrying 13ql4 deletion showed 18% -98% (median value; 72.5% ) and 22% -98. 5% ( median value: 76. 5% ) of deleted nuclei involving the RBI and the D13S319 locus (P = 0.38). There were 67.9% (36 out of 53)and 66% (35 out of 53)cases carrying >65% of 13ql4.1 -rn14.2 and 13ql4.3 deleted nuclei as high proportion deletion patients, respectively (P =0.188). The positive rate of the high proportion deletion patients had still no difference between LSI-RBI and LSI-D13S319 groups when the cut-off value was defined as 85% ( p =0. 439). In conclusion, in this cohort of 112 MM patients, there was no significant difference between the LSI-RBland LSI-D13S319 probes to detect 13ql4 deletion. Both LSI-RBI and LSI-D13S319 probes can be selected to detect 13ql4 deletion in MM patients. All the 53 MM patients with 13ql4 deletion had deletions of 13ql4. 1 - 14.2 and 13ql4. 3 regions, which is a large deletion as one of the important characters in MM patients with 13ql4 deletion.%染色体13q14缺失是多发性骨髓瘤(MM)常见的遗传学异常,也是荧光原位杂交(FISH)检测的常规指标.目前针对该片段缺失的商品化序列特异性DNA探针有LSI-RB1(针对13q14.1 - 14.2区域)、LSI-D13S319(针对13q14.3区域)和LSI-D13S25(针对13q14.3区域)3种.本研究联合应用LSI-RB1、LSI-D13S319探针和间期FISH方法同时检测112例MM患者对应区域的缺失,比较MM患者上述区域缺失率和缺失细胞比例是否存在差异,总结我国MM患者13q14缺失片段大小的特点,以更好地指导临床检测和治疗.结果表明:①LSI-RB1和LSI-D13S319两种探针对MM患者13q14缺失的检出率均为47.3％,检出相符率为100％；如果将缺失的阈值提高至20％,则13q14缺失检出率分别为46.4％和47.3％,检出相符率为98％；②RB-1缺失组缺失细胞比例中位数为72.5％(18％-98％),D13S319缺失组缺失细胞比例中位数为76.5％(22％ - 98.5％),2种探针检测得出的13q14缺失细胞比例无统计学差异(P=0.38)；如果分别将缺失细胞比例≥65％和≥85％定为高比例缺失,比较两种探针对高比例缺失患者的检出率,结果RB1组有36例(67.9％)和14例(26.4％)为高比例缺失,D13S319组有35例(66％)和19例(35.8％)为高比例缺失,统计学分析显示两种探针对高比例缺失患者的检出率也无显著差异(P分别为0.188和0.439)；③53例13q14缺失MM患者均为杂合型缺失,且同时具有上述两个区域缺失,即均为较大片段缺失.结论:本研究中112例MM患者13q14.1 -14.2和13q14.3区域缺失、缺失细胞比例和高比例缺失检出率无明显差异,不能根据检测上述两个位点将MM患者划分为不同亚型,在检测13q14缺失时,仅需选择LSI-RB1和LSI-D13S319中1种探针即可.53例13q14缺失MM患者均同时存在13q14.1 - 14.2和13q14.3两个区域的缺失,提示较大片段缺失是MM患者13q缺失的重要特点之一.
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