Fig. 1From: Performance of non-invasive prenatal testing for trisomies 21 and 18 in twin pregnanciesKaryotyping results of 3 cases. a and b, case 1, Normal/T18; c and d, case 2 Normal/T21; e and f, case 3, Normal/T21; g and h, case 4 Normal/T21; i and j, case 5 Normal/T21. Triploid chromosomes have been outlined with red lineBack to article page