De novo trisomy 16p.

We report on a patient with psychomotor retardation and a pattern of malformations comprising single umbilical artery, craniofacial anomalies, severe truncal hypotonia, and lower-limb hyporreflexia. G-banding cytogenetics demonstrated a 16p+ chromosome. Parental chromosomes were normal. The use of fluorescent in situ hybridization (FISH) showed that this extra material derived from chromosome 16. High-resolution G-banding demonstrated a duplicated segment on the 16p arm, confirming our suspicion of a de novo tandem duplication; hence, the cytogenetic diagnosis was given as 46,XY,dir dup(16)(p11.2-->p12).

Deletion of exon b3 of the BCR gene in CML: easy breakpoint mapping by a two-round PCR.

We have performed the molecular analysis for the detection of the BCR-ABL and ABL-BCR fusion genes in 50 patients with myeloproliferative disorders. All patients diagnosed with CML (13 out of 50) were positive for the BCR-ABL hybrid. Six CML patients (46%) showed ABL-BCR amplifications of the Ib-BCR type. All rearrangements but one were concordant. The aberrant case presented a deletion of exon b3, in addition to the alternative Ib-BCR and Ia-BCR. Its possible origin and relevance are briefly discussed.

BCR-ABL rearrangement and 'variant' Philadelphia chromosome in de novo acute myelogenous leukaemia FAB subtype M1.

We report a case of de novo acute myelogenous leukaemia FAB subtype M1 that presents a cytogenetic complex translocation between chromosomes 7, 9 and 22, producing a 'variant' Philadelphia chromosome. Molecular analysis revealed a BCR-ABL rearrangement involving exons b3 and a2 (b3a2). Haematological parameters and genetic analysis again raise the problem of the true nature of this disease, which is briefly discussed.