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ObjectiveIn prenatal diagnosis, some polymalformed foetuses with suspicion of chromosomal abnormalities have normal standard karyotype. Routine chromosome analysis identifies structural rearrangements greater than 5Mb but cannot identify abnormalities of the telomeric regions or microdeletions reliably. Molecular cytogenetic techniques were developed to overcome these limitations. BAC-based array comparative genomic hybridization array (CGH-array) were developed to increase the resolution of chromosomal studies and to provide a comprehensive assay by using large-insert clones as the target for analysis. We propose to use this technology to better understand the pathology in few foetuses with polymalformation syndrome and apparently balanced karyotype.Materials and methodsComparative genomic hybridization has been used extensively to document gains and losses of genomic DNA in diseases such as cancer and mental retardation the development of CGH using arrays has improved the resolution of these analyses, allowing better detection. We used DNA microarrays (Genosystem®) according to their instruction. Abnormalities have been confirmed by Fish.ResultsIn three cases, this technology allowed us to correlate the abnormal phenotype with an imbalance chromosomal abnormality, (a tetrasomy 12p corresponding to a Pallister-Killian syndrome, a deletion of 7qter on derivative 10 of an inherited maternal reciprocal translocation t(7;10). In the third case, the prenatal caryotype of a foetus with holoprosencephaly showed a de novo apparently balanced reciprocal translocation t(7;8). By Fish, we identified an additional deletion in the region of the Sonic Hedgehog gene.Discussion and conclusionWe show the feasibility and the usefulness of CGH-array in constitutional cytogenetics.

It has been recognized that chromosomal abnormalities are one of the most important causes of the high mortality rate in human concepti. Among these abnormalities, the unbalanced transmission of a parental chromosomal rearrangement is frequently observed, and couples with a history of pregnancy losses are therefore referred for genetic counselling and to establish their karyotype. Unbalanced chromosomal rearrangements involving telomeres are emerging as an important cause of mental retardation and/or congenital malformations in humans. As suggested by several authors, they could also be responsible for recurrent miscarriages. The aim of this study was to screen cryptic chromosome abnormalities in couples referred to our laboratory for recurrent unexplained miscarriages.

BACKGROUND: It has been recognized that chromosomal abnormalities are one of the most important causes of the high mortality rate in human concepti. Among these abnormalities, the unbalanced transmission of a parental chromosomal rearrangement is frequently observed, and couples with a history of pregnancy losses are therefore referred for genetic counselling and to establish their karyotype. Unbalanced chromosomal rearrangements involving telomeres are emerging as an important cause of mental retardation and/or congenital malformations in humans. As suggested by several authors, they could also be responsible for recurrent miscarriages. The aim of this study was to screen cryptic chromosome abnormalities in couples referred to our laboratory for recurrent unexplained miscarriages. METHODS AND RESULTS: Karyotyping was performed in 57 couples (114 patients). A detectable chromosomal abnormality was diagnosed in seven cases, thus limiting the analysis of telomeres to only 100 patients. Two different protocols were used according to the number of metaphases on slides. No telomeric chromosome abnormality was detected in our study. CONCLUSION: The use of FISH telomeric probes is not of clinical interest in the systematic screening of couples with multiple miscarriages and should be performed only in those with a familial history of mental retardation and congenital malformations.

We report a case of oligoasthenoteratozoospermia in a 40 year-old patient with a familial history that revealed multiple cases of infertility and perinatal deaths. The patient's semen sample contained 2x10(6) spermatozoa/ml, with an overall progressively motile population of <5%. Cytological analysis revealed a teratozoospermia with 100% of abnormal macrocephalic sperm heads and an irregular acrosomal cap in 38% of cells. Moreover, 72% of spermatozoa carried multiple flagella (2-5). The midpiece was elongated and/or enlarged with cytoplasmic droplets in 15% of cells. The multiple anomalies index (MAI) was 3.3 (normal value = 1.6), reflecting the high incidence of spermatozoal morphological abnormalities in this patient. Ultrastructural analysis revealed the presence of 2 or 3 vacuolated nuclei per sperm head. The acrosome was abnormal and the chromatin, partially packaged, appeared rough. In some cases, a large amount of cytoplasm containing vacuoles was observed around the nucleus and the acrosome. The mitochondrial helix was disorganized. Chromosome analysis performed on blood cells revealed a normal karyotype. Three-colour fluorescence in-situ hybridization (FISH) analysis of 1148 spermatozoa showed 21.6% to be diploid, 62.4% triploid, 13.3% quadriploid and 2.7% hyperploid (<4n). In conclusion, we suggest that this case could result from a genetically induced spermiation failure, the origin of which is discussed.

To assess the frequency of chromosomal aberrations in French candidates for intracytoplasmic sperm injection (ICSI), and to explore the existence of a female chromosomal factor in some cases of couple infertility, a collaborative retrospective clinical and cytogenetic study was performed, launched by the Association des Cytogénéticiens de Langue Franciaise (ACLF). The karyotypes of 3208 patients [2196 men (68.4%), 1012 (31.6%) women] included in ICSI programmes over a 3-year period in France were collected. A total of 183 aberrant karyotypes was diagnosed, corresponding to an abnormality frequency of 6.1% (134/2196) for men and 4.84% (49/1012) for women. The following frequencies of abnormalities were observed respectively for men and women: 1.23% (n = 27) and 0.69% (n = 7) for reciprocal translocations, 0.82% (n = 18) and 0.69% (n = 7) for Robertsonian translocations, 0.13% (n = 3) and 0.69% (n = 7) for inversions, 3.32% (n = 73) and 2.77% (n = 28) for numerical sex chromosome aberrations, and 0.59% (n = 13) and 0% for other structural aberrations. Among the male patients of this latter group, 0.40% (n = 9) had a Y chromosome abnormality. Among the male patients with numerical sex chromosome abnormalities, 2.23% (n = 49) were 47,XXY, 0.32% (n = 7) were 47,XYY, and 0.77% (n = 17) had a mosaicism for numerical sex chromosome anomalies. All the female patients with sex chromosome abnormalities (2.77%, n = 28) had mosaicism for numerical sex chromosome anomalies. Even if these cases-the significance of which was sometimes questioned-were disregarded in the analysis, 2.08% (21/1012) of abnormal karyotypes remained in women. An overall increased frequency of chromosomal aberrations was found, and this confirmed that in some cases of poor reproductive outcome there may be a contribution of maternal chromosome aberrations. Indeed, the existence of a chromosome abnormality in the female partner was associated with the group of infertile men in which there was no apparent cause of infertility.

We report one case of a de-novo complex chromosomal rearrangement (CCR), t(1;5;13)ins(14;13), in an abnormal 19-month-old boy. Clinical features associated were a mild facial dysmorphy and a psychomotor retardation. Parental ages were, respectively, 29 years for the mother and 60 years for the father. We point out the usefulness of fluorescence in-situ hybridization in elucidating CCRs, and discuss the possible correlation between the existence of a chromosomal aberration and advanced paternal age.Keywords:complex chromosomal rearrangement/fluorescence in-situ hybridization/mental retardation/reproduction/paternal age

We report one case of a de-novo complex chromosomal rearrangement (CCR), t(1;5;13)ins(14;13), in an abnormal 19-month-old boy. Clinical features associated were a mild facial dysmorphy and a psychomotor retardation. Parental ages were, respectively, 29 years for the mother and 60 years for the father. We point out the usefulness of fluorescence in-situ hybridization in elucidating CCRs, and discuss the possible correlation between the existence of a chromosomal aberration and advanced paternal age.