Chromosomal anomalies in first-trimester miscarriages

BACKGROUND. It is well known that a large proportion of first-trimester spontaneous abortions is caused by chromosomal disorders. The present study represents a unique material and the success rate of the karyotyping was high. METHODS. Chromosomal analysis from chorionic villus sampling of 259 of 304 consecutive first-trimester miscarriages in the Uppsala County, Sweden is presented. RESULTS AND CONCLUSIONS. An abnormal karyotype was found in 61% of the cases. Autosomal trisomies were most frequently detected (in 37% of the karyotyped samples), followed by polyploidies (9%) and monosomy X (6%). Cases with an extra sex chromosome constituted approximately 5% of the karyotyped abortions, with a remarkable high frequency of 47,XXY (3.4%), that is approximately 40 times greater the prevalence of Klinefelter syndrome among live birth. Similar to autosomal chromosome abnormalities, present finding indicates that the majority of sex chromosome abnormalities do not survive to term. Autosomal trisomies and an extra X-chromosome in males (47,XXY) were associated with an advanced maternal age, whereas monosomy X as well as polyploidy changes seems to be inversely related to the age of the mother. The single most common aberration was trisomy 16, which was found in 14% of the chromosomally abnormal abortions.