染色体断裂实验联合基因突变检测在范可尼贫血诊断中的应用

The Application of Chromosome Fragmentation Test Combined with Mutation Detection in Diagnosis of Fanconi Anemia

目的探讨染色体断裂实验联合二代测序检测技术在范可尼贫血(FA)基因突变尤其是FA嵌合患者诊断中的应用价值。方法收集疑似FA的患儿2例,取外周血细胞进行0,25,50与100ng/mL丝裂霉素C(MMC)诱导染色体断裂实验,同时应用二代测序对2例患儿及其父母进行5种常见的FA基因突变检测。结果 (1)患儿1:染色体断裂实验结果显示,在25ng/mL的MMC诱导下,染色体畸变率未明显高于对照组,仅在MMC浓度为50与100ng/mL时,染色体畸变率(23.33%和44.33%)显著高于对照组(14.67%和26.67%),为可疑阳性。经基因突变检测,发现FANC C基因突变,突变位点为C.973G>A/p.A325,其父亲也检测到相应的位点突变,而母亲并未发现。(2)患儿2:染色体断裂实验结果显示,在25ng/mL的MMC诱导下,染色体畸变率(13.33%)已明显高于对照组(5.33%),实验结果阳性。二代测序结果也检测到FANC A基因突变,突变位点为c.A796G>p.T266A、c.G2426A>p.G809D、c.G1235T>p.A412V、c.A3982G>p.T1328A。结论染色体断裂实验结合基因突变检测可为FA的确诊提供较可靠的依据,还可确定FA的基因型,对FA患者尤其是临床症状不典型者的诊断有重要意义。

Objective To explore the value of the chromosome fragmentation test with mutation detection for the diagnosis of Fanconi anemia(FA),especially in chimaeras. Methods DNA breakage of peripheral whole blood cells from two children who were likely to have FA was examined with MMC-induced chromosome breakage at different concentrations(0,25,50 and 100 ng/mL). Meanwhile the second generation sequencing technique was used to test FANC gene mutation in the two children and their parents. Results (1)Nochromosome breakage breakage were found in any groups without MMC. The aberrant rate at the concentration of MMC 25 ng/mL in child 1 was similar to the controls. But,at the concentrations of MMC 50 and 100 ng/mL,the aberrant rate(23.33%and 44.33%)was higher than the controls(14.67%and 26.67%). While gene mutation C.973G>A/p.A325 were found in FANC C. (2)In child 2,the aberrant rate were much higher than the controls,with the higher concentration of MMC from 25 to 100 ng/mL. The mutation of c.A796G>p.T266A,c.G2426A>p.G809D,c.G1235T>p.A412V,and c.A3982G>p.T1328A was found in child 2.Therefore the two children could be considered as FA. Conclusion The combination of mutation detection with the second generation sequencing of chromosome breakage can provide the basis for the diagnosis of FA.