Table 4. Analysis of PTEN gene copy number by FISH.
| PTEN locus | Number of cases (%) |
|---|---|
| Hemizygous deletiona | 42 (39%) |
| Homozygous deletionb | 5 (5%) |
| Not deleted | 60 (56%) |
Abbreviation: FISH, fluorescence in situ hybridisation.
a
Hemizygous deletion of PTEN was defined as >20% of tumour nuclei containing one PTEN locus signal (mean + 3 s.d. in non-neoplastic controls) (Korshunov et al, 2005).
b
Homozygous deletions of PTEN was identified by the simultaneous lack of both of the PTEN locus signals and by the presence of CEP 10 signals in >30% of cells (Korshunov et al, 2005).