TY - JOUR
T1 - Cytogenetic analyses of human oocytes provide new data on non-disjunction mechanisms and the origin of trisomy 16
AU - Garcia-Cruz, R.
AU - Casanovas, A.
AU - Brieño-Enríquez, M.
AU - Robles, P.
AU - Roig, I.
AU - Pujol, A.
AU - Cabero, L.
AU - Durban, M.
AU - Garcia Caldés, M.
N1 - Funding Information:
RG-C was a recipient of a grant from the Agència de Gestió d’Ajuts Universitaris i de Recerca de la Generalitat de Catalunya (2004FI00953). This study has been supported by the Ministerio de Ciencia y Tecnología (BFU2006-1295).
PY - 2010/1/1
Y1 - 2010/1/1
N2 - Background: Nowadays, oocyte donation is an extended practise in IVF programmes. However, to date, little information on aneuploidy frequency in oocytes from donors is available. Aneuploidy is one of the major causes of embryo and fetal wastage as well as of congenital mental and developmental disabilities. It is known that most aneuploidies are due to non-disjunction events occurring in the maternal germ line. Linkage studies have associated abnormal patterns of meiotic recombination to the origin of the non-disjunction event in many aneuploid conditions. methods and results: In the present study, we analyse the frequency of chromosome imbalances in a series of metaphase I (MI; n 44) and metaphase II (MII; n 103) oocytes from 140 young donors (aged from 18 to 35 years, mean age 26.6) after hormone-induced superovulation. The aneuploidy frequency found in MII oocytes was 12.6%, and both whole-chromosome non-disjunction (1.94%) and premature separation of sister chromatids (PSSC) (12.6%) have been found. The chromosomes involved have been identified by multiplex fluorescent in situ hybridization (FISH). Achiasmate chromosomes have been identified in MI oocytes (9.1%), with most of them corresponding to chromosome 16 (6.8%). For this reason, the meiotic recombination pattern of chromosome 16 has been analysed in prophase I oocytes (n 81) by immunofluorescence staining against MLH1 protein and subsequent FISH with specific probes. Our results show a percentage of oocytes with non-crossover bivalent 16 (2.5%) and a high percentage of bivalents 16 with a single exchange (19.8%). conclusions: In the present study, we report the finding of a considerable frequency of aneuploidy in oocytes from young donors, with the frequency of PSSC being higher than the frequency of whole-chromosome non-disjunction. In addition, we report vulnerable patterns of meiotic recombination in chromosome 16 that may be at risk of leading to a non-disjunction event. This gives new data on the susceptibility of the control population to conceive a trisomic 16 embryo.
AB - Background: Nowadays, oocyte donation is an extended practise in IVF programmes. However, to date, little information on aneuploidy frequency in oocytes from donors is available. Aneuploidy is one of the major causes of embryo and fetal wastage as well as of congenital mental and developmental disabilities. It is known that most aneuploidies are due to non-disjunction events occurring in the maternal germ line. Linkage studies have associated abnormal patterns of meiotic recombination to the origin of the non-disjunction event in many aneuploid conditions. methods and results: In the present study, we analyse the frequency of chromosome imbalances in a series of metaphase I (MI; n 44) and metaphase II (MII; n 103) oocytes from 140 young donors (aged from 18 to 35 years, mean age 26.6) after hormone-induced superovulation. The aneuploidy frequency found in MII oocytes was 12.6%, and both whole-chromosome non-disjunction (1.94%) and premature separation of sister chromatids (PSSC) (12.6%) have been found. The chromosomes involved have been identified by multiplex fluorescent in situ hybridization (FISH). Achiasmate chromosomes have been identified in MI oocytes (9.1%), with most of them corresponding to chromosome 16 (6.8%). For this reason, the meiotic recombination pattern of chromosome 16 has been analysed in prophase I oocytes (n 81) by immunofluorescence staining against MLH1 protein and subsequent FISH with specific probes. Our results show a percentage of oocytes with non-crossover bivalent 16 (2.5%) and a high percentage of bivalents 16 with a single exchange (19.8%). conclusions: In the present study, we report the finding of a considerable frequency of aneuploidy in oocytes from young donors, with the frequency of PSSC being higher than the frequency of whole-chromosome non-disjunction. In addition, we report vulnerable patterns of meiotic recombination in chromosome 16 that may be at risk of leading to a non-disjunction event. This gives new data on the susceptibility of the control population to conceive a trisomic 16 embryo.
KW - Aneuploidy
KW - Chromosome non-disjunction
KW - Meiotic recombination
KW - Oocyte donor
KW - Trisomy 16
UR - http://www.scopus.com/inward/record.url?scp=72849147965&partnerID=8YFLogxK
U2 - 10.1093/humrep/dep347
DO - 10.1093/humrep/dep347
M3 - Article
VL - 25
SP - 179
EP - 191
IS - 1
ER -