Diandric triploidy is characterized by a combination of increased free BHCGMoM and moderately decreased PAPP-A MoM, similar to the biochemical profile of cases of
trisomy 21. On the other hand, in cases of digynic triploidy, the biochemistry demonstrates markedly decreased free BHCG and PAPP-A MoMs (2,8).
The research shared by
Trisomy 21 Research Society included the first two studies that analyzed specific biomarkers, measurable substances indicative of a disease, infection, or environmental exposure and cerebrospinal fluid.
Trisomy 21 was confirmed by karyotyping 20 well-spread metaphases following amniotic fluid sampling.
SD-QF-PCR confirmed all 60 patients with DS to be positive for
trisomy 21. Figure 2a shows the resulting peak in the case of euploids, the expected value was between 0.9 to 1.1, whereas for the trisomy, the value changes to 1.4 to 1.6, confirming the presence of an extra region.
Norton et al demonstrated a 79 percent sensitivity and 3.4 percent positive predictive value (PPV) for
trisomy 21 using standard first-trimester screening in all patients.
LifeCodexx is currently rolling-out its new, low cost qPCR-based solution for
trisomy 21 analysis.
The noninvasive screen yields results for
trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), trisomy 13 (Patau syndrome), as well as certain sex chromosome-related disorders.
Currently, NIPS is reported to reach 99% sensitivity and specificity in
trisomy 21 detection, making it a great tool for prenatal screening of Down syndrome (16).
The clinical evidence study of Illumina's Verifi was comprised of more than 85,000 clinical samples and demonstrated observed sensitivity and specificity of
trisomy 21 at greater than 99%.
This case highlights the relationship between
trisomy 21 and Moyamoya syndrome.