BACKGROUND: Ring chromosomes are normally associated with @entity600 and are rarely inherited. An exception to this rule is provided by deletion/ring cases. We were provided with a unique opportunity to investigate the meiotic segregation at oogenesis in a @entity1 who is a carrier of a deleted/ring 22 chromosome. The couple requested preimplantation genetic diagnosis (PGD) following the birth of a son with a mosaic karyotype.The couple underwent two cycles of PGD. Studies were performed on lymphocytes, single embryonic cells removed from 3 day-old embryos and un-transferred embryos. Analysis was carried out using fluorescence in situ hybridisation (FISH) with specific probe sets in two rounds of hybridization. RESULTS: In total, 12 embryos were biopsied, and follow up information was obtained for 10 embryos. No embryos were completely normal or balanced for chromosome 22 by day 5. There was only one embryo diagnosed as balanced of 12 biopsied but that accumulated postzygotic errors by day 5. Three oocytes apparently had a balanced chromosome 22 complement but all had the deleted and the ring 22 and not the intact chromosome 22. After fertilisation all the embryos accumulated postzygotic errors for chromosome 22. CONCLUSION: The study of the preimplantation embryos in this case provided a rare and significant chance to study and understand the phenomena associated with this unusual type of @entity154 during @entity4523 and in the earliest stages of development. It is the first reported PGD attempt for a @entity2008 .

Meiotic and mitotic behaviour of a ring/deleted chromosome 22 in XXXX embryos determined by preimplantation genetic diagnosis for a maternal carrier.

@entity1 :: ('9606', 'Species') :: ['woman'] @entity154 :: ('MESH:D000013', 'Disease') :: ['anomaly'] @entity4523 :: ('MESH:D048629', 'Disease') :: ['meiosis'] @entity600 :: ('MESH:D000014', 'Disease') :: ['developmental anomalies'] @entity2008 :: ('MESH:D002869', 'Disease') :: ['ring chromosome abnormality']
@entity1 :: (9606,Species) :: ['human']
