The IONA® Test: Development of an Automated Cell-Free DNA-Based Screening Test for Fetal Trisomies 13, 18, and 21 That Employs the Ion Proton Semiconductor Sequencing Platform.

OBJECTIVE: To develop a screening test for fetal trisomy 13, 18, and 21 using cell-free DNA from maternal blood with an automated workflow using the Ion Proton sequencing platform. METHODS: An automated next-generation sequencing workflow was developed using the Ion Proton sequencing platform and software developed for straightforward bioinformatic analysis. An algorithm was developed using 239 samples to determine the likelihood of trisomy, using DNA fragment counts and a fetal fraction validity check; the results were compared with those from invasive diagnostic procedures. A further 111 samples were used to assess the tests' sensitivity (detection rate) and specificity (1 minus false-positive rate). RESULTS: The 110 of a possible 111 valid samples used to verify the IONA® test gave 100% sensitivity and specificity, compared with invasive diagnostic procedures; one failed the fetal fraction validity check giving a sample failure rate of 0.29% across all 350 analysed samples. CONCLUSION: The data indicate that the IONA test provides a robust, accurate automated workflow suitable for use on maternal blood samples to screen for trisomies 13, 18, and 21. The test has the potential to reduce the number of unnecessary invasive procedures performed and facilitate testing by screening laboratories.

Continuous parallax in discrete pixelated integral three-dimensional displays.

An evaluation of the retention of continuous parallax in pixelated integral three-dimensional image displays is presented. The integral image capture process is first considered, to provide a starting point for the investigation. The complementary display system is then examined in detail. The viewing geometry of the display system is analyzed to provide a foundation for the work to follow, and an experimental investigation and simulations of the characteristics of emitted ray bundles are presented. Next, an analytical model of decoding lenslet array operation is derived, leading to an understanding of the process responsible for production of continuous parallax in replay. It is found that if the lateral resolution of the lenslet is matched to that of the display, continuous parallax is retained in the replayed image, where the finite aberration-limited resolution of the lenslet acts to produce a low-pass reconstruction filter. A condition is derived for optimal continuous parallax in replay, based on a relationship between pixel width and lenslet rms spot size.