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Background: Chromosomal anomalies are a recognized cause of stillbirth, accounting for 6-17% of the cases. As a diagnostic laboratory method in this setting, conventional karyotyping has two main drawbacks: the need for viable fetal cells in a dead fetus and its limited resolution as compared to alternative techniques., Objective: To assess the effectiveness of cytogenetic analysis in stillbirths between different testing methods and different sampled tissues., Methods: From 2011 to 2017, 145 stillborn fetuses (defined as fetal losses after 22 weeks) were delivered in our center. The stillbirth protocol includes genetic testing by means of a karyotype, QF-PCR, or chromosomal microarray analysis (CMA), depending on the presence of fetal structural anomalies and the study time period. The success rates were compared between tests and between different sampled tissues., Results: Consent was granted for cytogenetic analysis in 136 stillbirths. Test success rate was 100% (38/38) for CMA independent of the sampled tissue, 99% (65/66) for QF-PCR, and 66% (65/98) for karyotyping. The success rate for karyotyping was 48% (69/145) of the total tissues samples, showing great variation according to the tissue sampled: 83% (40/48) in amniotic fluid, 78% (21/27) in the placenta, 13% (7/54) in fetal skin, and 6.3% (1/16) in fetal blood. Four full or partial aneuploidies (trisomy 9, trisomy 22, tetrasomy 18p, and monosomy X) and 2 microdeletions (del2p16.3 and del1q13.2q13.4) were found, resulting in a 3.9% (4/103) prevalence for full or partial aneuploidy and a 5.3% prevalence (2/38) for submicroscopic abnormalities., Conclusions: Amniotic fluid should be the preferred tissue source in the cytogenetic analysis of stillbirth due to its high success rate. Between tests, CMA is a preferable method because of its higher test success rate, independent of the sampled tissue, and higher diagnostic yield including chromosomal and submicroscopic anomalies., (© 2020 S. Karger AG, Basel.)

Objective: To assess the distribution of the parental origin of the retained X chromosome in monosomy X, either in miscarriages or in ongoing pregnancies., Method: The parental origin of the X chromosome was determined in monosomy X pregnancies, either miscarriages or ongoing pregnancies. Microsatellite marker patterns were compared between maternal and fetal samples by quantitative fluorescence polymerase chain reaction. Distributions of maternally and paternally derived X chromosome were assessed in miscarriages and in ongoing pregnancies using two-tailed Fisher exact test., Results: Forty monosomy X pregnancies were included in the study: 26 miscarried at 5-16 weeks, and 14 ongoing pregnancies were diagnosed at 11-20 weeks. The retained X chromosome was maternally derived in 67% of the cases. In miscarriages, maternal and paternal X chromosome were retained in a similar proportion (54% [95% CI: 35-73%] vs. 46% [95% CI: 27-65%]), while in ongoing pregnancies, the maternal rate was 13 times higher (93% [95% CI: 79-100%)] vs. 7% [95% CI: 0-20%])., Conclusions: The retained X chromosome in individuals with monosomy X should theoretically be maternally derived in 2/3 of the cases. Our study suggests a preferential early miscarriage in pregnancies with a retained paternally derived X chromosome. This may explain the observation that 75-90% of individuals with monosomy X retain the maternal X chromosome., (© 2017 S. Karger AG, Basel.)