EUROCAT study: Prenatal diagnosis and outcome of pregnancy of specified sex-chromosome abnormalities in Europe

An extra X-chromosome in males or females (XXX, XXY) and extra Y chromosome in males (XYY, Klinefelter?s syndrome) occur in approximately 18 per 10,000 pregnancies and most never get diagnosed. Figures for incidence at birth have been obtained from cytogenetic surveys of around 200,000 infants from UK, Denmark, Canada, USA and Japan.

Following prenatal detection parents receive information about the specific condition from a variety of professionals and from other sources. Some of this information may be outdated, inaccurate and unduly negative due to ascertainment bias. Following prenatal diagnosis some parents continue the pregnancy and some request termination of pregnancy. Rates of prenatal detection, information given to parents and differences in laws and practices regarding termination of pregnancy are some factors which may lead to differences in outcome.

Aims

• To report the total prevalence of 3 different sex chromosome abnormalities (XXX, XXY, XYY) diagnosed prenatally or before one year of age in Europe and by country, and estimate the proportion of affected fetuses/babies diagnosed prenatally or by one year of age.
• To describe the proportion and prevalence of prenatally diagnosed cases, gestational age at prenatal diagnosis, and the relationship between prevalence of prenatally diagnosed cases and average gestational age at prenatal diagnosis.
• To relate the prevalence of prenatally diagnosed sex chromosome anomalies to the extent of prenatal karyotyping in the country (as indicated by the proportion of Down?s syndrome cases detected prenatally, by maternal age).
• To describe the outcome of pregnancy of prenatally diagnosed cases.
• To describe prevalence of postnatally diagnosed cases and reasons for karyotyping in those cases up to one year of age.
• To describe trend over time in prevalence of prenatally diagnosed cases in 3 time periods 1990-1994, 1995-1999 and 2000-2005.