摘要目的:探讨1例嵌合型4号环状染色体患儿核型的成因、临床表型及发病机制。方法:选取2020年2月15日于滕州市妇幼保健院就诊的1例嵌合型4号环状染色体患儿为研究对象。收集患儿的临床资料，对其进行外周血染色体G显带核型分析、染色体微阵列分析(CMA)、荧光原位杂交(FISH)检测，并对文献进行回顾。结果:患儿为足月小样低体重儿，具有特殊面容、动脉导管未闭、室间隔缺损。外周血染色体核型为mos 46，XY，r(4)(p16.3q35.2)[259]/45，XY，-4[25]/47，XY，r(4)(p16.3q35.2)，+r(4)(p16.3q35.2)[8]/46，XY，der(4)del(4)(p16.3)inv(4)(p16.3q31.1)[6]/46，XY，dic？r(4；4)(p16.3q35.2；p16.3q35.2)[4]/48，XY，r(4)(p16.3q35.2)，+r(4)(p16.3q35.2)×2[3]/46，XY，r(4)(p1？q2？)[2]；CMA检测结果为arr[GRCh37]4p16.3(68 345-2 981 614)×1；FISH检测结果为45，XY，-4[12]/45，XY，-4×2，+mar1.ish r1(4)( WHS-， D4Z1+)[1]/46，XY，-4，+mar1.ishr1(4)( WHS-， D4Z1+)[73]/46，XY，-4，+mar2.ishr2(4)( WHS-， D4Z1++)[1]/47，XY，-4，+mar1×2.ishr1(4)( WHS-， D4Z1+)×2[4]/46，XY，del(4)(p16.3)．ish del(4)(p16.3)( WHS-， D4Z1+)[9]。 结论:患儿的4号环状染色体为新发变异，在胚胎发育过程中产生了多种细胞系，形成同源嵌合体。4号环状染色体综合征临床表型多变，与其本身的不稳定性、是否存在嵌合体核型、是否伴有缺失/重复及其范围等有关。

abstractsObjective:To explore the genetic basis, clinical phenotype and pathogenesis for a child with mosaicism ring chromosome 4.Methods:Clinical data of the child was collected. Peripheral blood chromosomal karyotype G banding analysis, chromosomal microarray analysis (CMA), fluorescence in situ hybridization (FISH) were carried out for the child, in addition with a review of the literature. Results:The child was born full-term with low birth weight, facial dysmorphism, patent ductus arteriosus and ventricular septal defect. His karyotype was determined as mos46, XY, r(4)(p16.3q35.2)[259]/45, XY, -4[25]/47, XY, r(4)(p16.3q35.2), + r(4)(p16.3q35.2)[8]/46, XY, der(4)del(4)(p16.3)inv(4)(p16.3q31.1)[6]/46, XY, dic? r(4; 4)(p16.3q35.2; p16.3q35.2)[4]/48, XY, r(4)(p16.3q35.2), + r(4)(p16.3q35.2)×2[3]/46, XY, r(4)(p1? q2? )[2]; CMA results was arr [GRCH37]4p16.3(68 345-2 981 614)×1; FISH results was 45, XY, -4[12]/45, XY, -4×2, + mar1.ish r1(4)( WHS-, D4Z1+ )[1]/ 46, XY, -4, + mar1.ishr1(4) ( WHS-, D4Z1+ )[73]/46, XY, -4, + mar2.ishr2(4)( WHS-, D4Z1+ + )[1]/47, XY, -4, + mar1×2.ishr1(4) ( WHS-, D4Z1+ )×2[4]/46, XY, del(4)(p16.3). ish del(4)(p16.3)( WHS-, D4Z1+ )[9]. Conclusion:In this case, the ring chromosome 4 as a de novo variant has produced a number of cell lines during embryonic development and giren rise to mosaicism. The clinical phenotype of ring chromosome 4 is variable. The instability of the ring chromosome itself, presence of mosaicism, chromosome breakpoint and range of deletion and/or duplication may all affect the ultimate phenotype.