[Analysis of a infertile female with ring 21 chromosome using combined techniques]

To investigate clinical phenotype and genetic characteristics of a 30-year-old infertile female carrying a mosaic ring 21 chromosome.

A combination of techniques including G-banding, C-banding, fluorescence in situ hybridization (FISH) and SNP array were performed to investigate the breaking point of the r(21).

The karyotype of the patient was mos 46,XX,r(21)[166]/46, XX,der(21)[60]/45, XX, -21[20]/46, XX,dic r(21)[4].ish del(21)(q22.2?)(21qter-, AML1+, D21S259/D21S341/D21S342+). arr 21q22.3(43 457 934-48 093 361) × 1, 21q22.2q22.3(40 218 429-43 457 934)× 1-2. The karyotypes of her parents were both normal.

Clinical phenotypes of patients carrying a ring 21 mainly depends on the percentage of abnormal cells and the deleted chromosomal fragment. The small uterus and oligomenorrhea in our patient may be attributed to the mosaic ring 21 chromosome.