Table 2. Relative frequency of genetic mechanisms in imprinting disorders.
| UPD(14)pat-like phenotype | BWS | SRS | AS | PWS | |
|---|---|---|---|---|---|
| Uniparental disomy | 65.4% | 16% | 10% | 3–5% | 25% (25%) |
| UPD(14)pat | UPD(11)pat (mosaic) | UPD(7)mat | UPD(15)pat | UPD(15)mat | |
| Cryptic deletion | 19.2% | Rare | — | 70% | 70% (72%) |
| Cryptic duplication | — | — | Rare | — | — |
| Epimutation | |||||
| Hypermethylation | 15.4% | 9% | — | — | 2–5% (2%) |
| Affected DMR | IG-DMR/MEG3-DMR | H19-DMR | — | — | SNRPN-DMR |
| Hypomethylation | — | 44% | >38% | 2–5% | — |
| Affected DMR | KvDMR1 | H19-DMR | SNRPN-DMR | ||
| Gene mutation | — | 5% | — | 10-15% | — |
| Mutated gene | CDKN1C | UBE3A | |||
| Unknown | 25% | >40% | 10% | ||
| Reference | This study | 17 | 18 | 19 | 8, 19 |
Abbreviations: AS, Angelman syndrome; BWS, Beckwith–Wiedemann syndrome; PWS, Prader–Willi syndrome; SRS, Silver–Russell syndrome.
Patients with abnormal karyotypes are included in BWS and AS, and not included in SRS. In PWS, the data including patients with abnormal karyotypes are shown, and those from patients with normal karyotype alone are depicted in parentheses.