1. Nathan R. Treff PhD Chief Science Officer
Detection of segmental and mosaic aneuploidy in preimplantation embryos and their reproductive potential
Nathan R. Treff PhD
Chief Science Officer

2. Frequency of mosaicism is misconceived

3. Primarily maternal meiotic (not mosaic)
Hassold and Hunt Nature :280

4. Origin of errors in preimplantation human embryos
1st polar body
2nd polar body
TE biopsy
maternal meiotic
Treff et al Fertil Steril 2008

5. Origin of errors in preimplantation human embryos
1st polar body
2nd polar body
TE biopsy
mitotic or paternal meiotic
Treff et al Fertil Steril 2008

6. ~67% of errors from maternal meiosis
Treff et al Fertil Steril 2008

7. Why are some mosaicism estimates so high?

8. Mosaicism or technical error?
0% consistency in embryos with aneuploidy!

9. Self correction or technical error?
0% consistency between day 3 and day 5!
Kearns et al., ASRM 2010, 2011, 2012, 2013 ASHG 2011, 2012, 2013, ESHRE 2011, 2012, 2013

10. aCGH False Positives False Positive Rate P=0.006 n=159 embryos
Capalbo et al. EJHG 2014

11. S-phase artifacts

12. Mosaicism classification schemes
Capalbo et al. Hum. Reprod. In Press

13. Mosaicism is not common
Capalbo et al. Hum. Reprod. In Press

14. Predictive Value of CCS?
Important to know if the test can be used to safely discard an embryo

15. SNP array predictive value
Scott et al. Fertil Steril

16. tNGS predictive value None with aneuploidy Sustained Implantation
Werner et al ASRM 2015

17. Impact of Mosaicism
No method of CCS can give a correct diagnosis when testing a mosaic embryo; by definition there will always be a sampling error
+15 N
+15
-15 N N N
+15
-15
-15
+15
-15

18. Mixture Model
Goodrich et al. JARG 2016

19. Comparison of methods to detect aneuploidy in a mixture
Goodrich et al. JARG 2016

20. ↑ sensitivity = ↓ specificity
Goodrich et al. JARG 2016

21. Mosaicism or artifact?
No evaluation of specificity/false positives!

22. Mosaicism classification schemes
Capalbo et al. Hum. Reprod. In Press

23. Contamination can look like mosaicism
VeriSeq PGS
NexCCS
Copy Number
Chromosome

24. Contamination detection (genotyping)
NexCCS
Copy Number
Pure
Chromosome
Allele Ratio 1
0.66
0.5
0.33
Chromosome

25. Contamination detection (genotyping)
NexCCS
Copy Number
Contaminated
Pure
Chromosome
Allele Ratio 1
0.66
0.5
0.33
Chromosome
Chromosome

26. Triploidy can also look like mosaicism
NexCCS
Triploidy can also look like mosaicism
Copy
Number
Triploid (2:1 allele ratios)
Allele Ratio 1
Diploid (1:1 allele ratios)
0.66
0.5
0.33
Allele Ratio 1
0.66
0.5
0.33

27. Segmental Aneuploidy

28. SNP array for translocations

29. Mitotic (reciprocal) segmental errors
5_2_B - 45,XX,+2p,+3, ++8p, -21,-22
2_2_A - 46,XY,-8,+10 1 2 3 4 1 2 3 4
5_2_C - 44,XX,-3p,-21,-22
2_2_B - 47,XY,+8 1 2 3 4 1 2 3 4
5_2_E - 44,XX,++3p,-21,-22 1 2 3 4
2_2_C – 44,XY,-8,-10 1 2 3 4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 X 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 X
Chromosome #
Chromosome #
5_3_A - 46,XX,-6,+8q 1 2 3 4 1 2 3 4
1_3_F- 45,XY,-15
5_3_D - 46,XX,i(8) 1 2 3 4 1 2 3 4
1_3_C - 48,XY,++15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 X 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 X
Chromosome #
Chromosome #
Kort et al. Human Reproduction. 2015

30. Segmental mosaicism platform comparison
Frequency of Detection
Mixture Level

31. Segmental mosaicism platform comparison

32. Segmental Aneuploidy Study Design
Prediction of segmental error
Original TE Bx
TE reBx 1
TE reBx 2
TE reBx 3
ICM section
Randomized blinded analysis
Juneau et al ASRM 2016

33. Uniform segmental
Juneau et al ASRM 2016

34. Reciprocal segmental
Juneau et al ASRM 2016

35. Observed in original biopsy only
Juneau et al ASRM 2016

36. Confirmed in at least one rebiopsy
Juneau et al ASRM 2016

37. Segmental Aneuploidy Predictive Value
88% predictive of remaining embryo
60% mitotic origin
artifact or true mosaicism
Juneau et al ASRM 2016

38. Segmental aneuploidy is associated with reduced success
115 20
189 12
p =
Werner et al ASRM 2016

39. Conclusions
Mosaicism is overestimated by inaccurate methods and weak criteria
Altered log2 ratios can originate from phenomena other than mosaicism
Criteria for diagnosing mosaicism from a single biopsy needs evaluation for specificity prior to clinical utilization
Segmental aneuploidy originates primarily from mitotic errors and may be predictive of reproductive potential