Structural rearrangements of chromosome 13 as additional abnormalities in Burkitt lymphoma and type 3 acute lymphoblastic leukemia.

We report three cases of chromosome 13 rearrangements as additional abnormalities in two patients with Burkitt lymphoma (BL) and one with type 3 acute lymphoblastic leukemia (ALL). Involvement of chromosome 13 has been reported most often as 13q+, without identification of the supplementary chromosomal material; in our three cases with 13q+, we identified two duplications: dup(13)(q13q22) and dup(13)(q21q22).

Monosomy 6q: report on four new cases.

We report on four patients with partial monosomy of the long arm of chromosome 6: two children presenting with an interstitial deletion del(6)(q14q16), the two others presenting with a terminal deletion del(6)(q25qter). These patients are compared with previous reports in the literature: 16 cases of terminal deletion and 17 cases of interstitial deletion. The deletions most often occur de novo. Mental retardation is always described. Dysmorphic facial features range between minor and major. There may be associated visceral abnormalities. After comparing the size and the localisation of the deletions with clinical data, we are now able to suggest a clinical localisation on chromosome 6.

Mosaic 46,XY/92,XXYY,del(5)(q13 q34) in an adult lymphoblastic leukemia.

Usually the chromosome anomalies encountered in ALL are modal number abnormalities (hyperdiploidy or hypodiploidy) and structural anomalies such as t(8;14), t(11;14), t(9;22), t(1;19) and del(6p). The 5q- syndrome is mainly associated with myelodysplastic syndromes and with ANLL (M1, M2, M3). We report the case of a patient presenting with a mosaic karyotype 46,XY/92,XXYY,del(5)(q13 q34) in the following proportion 1/3 normal mitoses and 2/3 tetraploid mitoses.