FISH and probes

We included CDKN2A (encoding p16 and p14) and CDKN2B (encoding p15), the two subunits of CDKN2, in our current study. The deletion of CDKN2 was defined as the loss of CDKN2A or CDKN2B which contained both hemizygous deletion and homozygous deletion genotypes. Interphase fluorescence in situ hybridization (I-FISH) experiments were performed with commercial kits (Cat No. LH009, Cytocell, Cambridge, UK) including two red-labeled CDKN2 probe kits, one red-labeled BCR and one green-labeled and ABL probe kit according to the manufacturers’ protocols (Fig. 1). Bone marrow cells of all patients were collected for detection of CDKN2 (covers a 193-kD region of 9q21.3, extending from 105 kD telomeric of p16 gene to 46 kD centromeric of CDKN2B) and BCR/ABL. We analyzed interphase cells according to the manufacturer’s instructions and the ISCN (2005) criteria [7].

Representative of fluorescence images in situ hybridization. a Normal cells presented with double green and red signals; b hemizygous cells presented with loss of one red signal; c homozygous cells presented with a loss of both red signals (p16) and only retained with two green signals (chromosome 9); d red and green signal fusion (BCR/ABL+)