Constitutional chromosome abnormalities among patients referred for blood karyotype analysis: a 5-year study at the AUBMC.

We report results on 2010 cases of blood referred for constitutional karyotype analysis. Referrals were grouped into 16 different categories, of which reproductive failure represented the highest percentage (33%), followed by structural congenital abnormalities (14.17%), developmental delay (11.34%), Down syndrome (9.65%), and abnormal sexual development (8.16%), while other categories represented smaller percentages. The total rate of abnormality was 16%, and the highest abnormality rates were among the clinically-recognizable chromosomal syndromes, while lower percentages were detected among less specific referrals. However, abnormality rates were generally different from the typical reported rates, probably due to the inclusion of cases not requiring chromosome analysis or the failure to recognize specific chromosomal syndromes. Other identified problems included lack of proper phenotypic description and difficulty in obtaining familial follow-up for proper diagnosis and genetic counseling.

Karyotype of amniotic fluid cells at the AUB-MC results on 2000 cases.

We report results on 2000 cases of amniotic fluid referred for karyotype analysis. Referrals were advanced maternal age in 64% of cases and abnormal ultrasound in 12% of cases. The frequency of chromosome aneuploidy was 2.4% in the first category and that of chromosome abnormalities 8% in the second. The incidence of marker chromosomes was 0.25%, that of mosaicism 0.3%, and maternal cell contamination was observed in 0.6% of cases. The overall culture failure rate was 0.9%. Our results are mostly in accordance with figures from larger surveys, published in the literature and differences might be due to the smaller number of samples in this series and variation in referral and/or sampling protocols.