Rapid prenatal diagnosis of common chromosome aneuploidies
Genomewide strategies offer the distinct advantage of unbiased detection of aberrations throughout the genome; however, because the power to detect fetal aneuploidies
is correlated with the sequencing depth required for counting-based detection (16, 17), genome-wide strategies are limited by the volume of sequence data required, typically >10 million sequencing reads per sample for trisomies 21, 18, and 13 (18).
While the technology for fetal cfDNA testing becomes more refined and there is general acknowledgement of its high detection rate for the common aneuploidies
, several recommendations have been made about the place of NIPT in contingency screening, in both the first and second trimesters.
North America held largest share in the global market of cell-free fetal DNA testing followed by Europe, Japan and Asia Pacific owing to high occurrence of several diseases and increasing number of aneuploidies
, great advancement in field of aneuploidy screening and developed healthcare infrastructure.
The risk for aneuploidies
increases with maternal age.
15) In prenatal series, trisomies 13, 18, and 21 make up approximately two-thirds of all clinically significant aneuploidies
In this study, we tested chorionic samples from miscarriage to identify aneuploidies
or abnormal numbers of 13, 16, 18, 21, 22, X and Y by FISH.
The follow-up of these patients was not complete, but the authors estimate that in 20%-44% of cases where multiple aneuploidies
are detected and the results are discordant, an occult maternal cancer is the explanation.
Application of the short tandem repeat loci in prenatal diagnostics of the most common aneuploidies
Human female meiosis, in particular, is inherently prone to errors, as evidenced by the high incidence and complexity of aneuploidies
in stillbirths and spontaneous abortions (Hassold and Hunt 2001).
Preimplantational genetic diagnosis: single aneuploidies
The companies have agreed to collaborate in the development and launch of a trisomy 21 laboratory developed test and other aneuploidies
testing in Germany, Austria, Switzerland, and Liechtenstein, with the potential for additional launches in other countries.
Even though aneuploidies
usually occur in autosomal chromosomes, sex chromosome aneuploidies
may also be associated with hyperdiploidy in ALL.
The patients' karyotypes and their relevant frequencies Karyotype Frequency Percentage (%) 46,XX 145 53 46,XY 73 26,7 Sex Chromosome Aneuploidies
mos 45,X/46,XY 4 1,5 mos 45,X/47,XXX/46,XX 1 0,4 mos 45,X/47,XXX/46,XX 1 0,4 mos 47 XXY/48 XXXY/46 XX/46 XY 1 0,4 47,XXY 29 10,5 mos 47,XXY/46,XY 8 2,9 Polymorphisms 46,XX 16 qh+ 4 1,5 46,XY Yqh+ 5 1,82 46,XYqh- 2 0,9 46,XY inv (9) (p11q12) yqh+ 1 0,5 46,XY 1qh+ 1 0,5
The cells are checked for abnormalities called aneuploidies
, which involve missing or extra copies of chromosomes.