Table 6.
Description and incidence of uniparental disomies (UPD).
| Type of abnormality | No. investigated cases | No. UPD | Type of CPM or TFM | UPD incidence (%) |
|---|---|---|---|---|
| trisomy 2 | 62 | - | - | - |
| trisomy 7 | 60 | - | - | - |
| trisomy 6 | 2 | - | - | - |
| trisomy 11 | 3 | - | - | - |
| trisomy 14 | 10 | 2 | 2 (CPM type I) | 20 |
| trisomy 15 | 24 | 1 | 1 (CPM type II) | 4.2 |
| trisomy 16 | 17 | 3 | 2 (CPM type III) + 1 (TFM type VI) | 17.6 |
| trisomy 20 | 25 | - | - | - |
| sSMC, others | 40 | - | - | - |
| Total | 243 | 6 | 5 CPM and 1 TFM | 2.5 |
CPM = confined placental mosaicism; TFM = true fetal mosaicism; sSMC = small supernumerary marker chromosome; Others = translocations, deletions, inversions involving imprinted chromosomes.