t(X;11)(q22;q23) KMT2A/?

2011-02-01   Adriana Zamecnikova 

1.Kuwait Cancer Control Center, Laboratory of Cancer Genetics, Department of Hematology, Shuwaikh, 70653 Kuwait

Clinics and Pathology

Disease

The chromosomal translocation t(X;11)(q22;q23) occurs very rarely, with only three cases of infants young children having been described in the literature; 2 AML cases: a 3 years old male, diagnosed with AML-M2 (Harrison et al., 1998) and 2 years old female diagnosed with acute megakaryoblastic leukemia (FAB type M7) (Ribeiro et al., 1993). The one ALL case described in a 4 years old male had a complex karyotype with chromosomal translocation t(11;14)(q13;q32), and monosomy 22 (Soszynska et al., 2008). Of note, the fourth AML (FAB type M2) case reported by Slater in a 10 months old male was shown to involve the SEPTIN6 gene located on Xq24 (Slater et al., 2002).

Phenotype stem cell origin

Suggested involvement of a pluripotent stem cell or a myeloid progenitor cell; myeloid lineage.

Etiology

No known prior exposure.

Epidemiology

Only 3 cases to date, sex ratio 2M/1F.

Prognosis

From the known data, the 3 years old male, diagnosed with AML-M2 remained alive in complete remission at 97 months; the ALL patient was in complete remission after 39 months.

Cytogenetics

Note

Breakpoints difficult to ascertain; cytogenetic appearance may be similar to t(X;11)(q13;q23) involving the AFX gene that fuses to MLL in acute leukemias.

Cytogenetics morphological

t(X;11)(q22;q23).

Additional anomalies

Sole abnormality in AML-M2 case, part of a hyperploid karyotype associated with +6, +8, +19, +21, +21 in a child with acute megakaryoblastic leukemia and complex karyotype in ALL case associated with t(11;14)(q13;q32), and monosomy 22, indicating that the t(X;11)(q22;q23) is likely to be a secondary anomaly to t(11;14)(q13;q32) in ALL.

Genes Involved and Proteins

Note
The gene in Xq22 is yet unknown, it is therefore uncertain whether this translocation involve a new MLL partner.
Gene name
KMT2A (myeloid/lymphoid or mixed lineage leukemia)
Location
11q23.3
Note
The MLL gene is frequently disrupted by a variety of chromosomal rearrangements that occur in acute myeloblastic leukemia (AML) and in acute lymphoblastic leukemia (ALL), with a peak incidence in infant leukemia as well as in secondary, topoisomerase II inhibitor-related leukemia.
Dna rna description
The MLL genomic structure consists of 36 exons distributed over 100 kb, the mRNA of ~11.9 kb encodes a 3969 amino-acid nuclear protein with a molecular weight of of 430 kDa.
Protein description
The MLL protein is a multi-domain molecule with regions of homology to diverse proteins; a major regulator of class I homeobox (HOX) gene expression.

Result of the Chromosomal Anomaly

Note

5 MLL - PARTNER GENE 3.
MLL translocation breakpoints cluster within an 8.3-kb region spanning exons 5-11; genomic breakpoint junction usually created on the der(11) chromosome.

Oncogenesis

Expression of a chimeric protein with actively transforming properties; altered patterns of MLL activity in hematopoietic stem cells resulting in blockage of hematopoietic maturation.

Bibliography

Pubmed IDLast YearTitleAuthors
95932861998Ten novel 11q23 chromosomal partner sites. European 11q23 Workshop participants.Harrison CJ et al
82201281993Acute megakaryoblastic leukemia in children and adolescents: a retrospective analysis of 24 cases.Ribeiro RC et al
120963482002MLL-SEPTIN6 fusion recurs in novel translocation of chromosomes 3, X, and 11 in infant acute myelomonocytic leukaemia and in t(X;11) in infant acute myeloid leukaemia, and MLL genomic breakpoint in complex MLL-SEPTIN6 rearrangement is a DNA topoisomerase II cleavage site.Slater DJ et al
186336152008The application of conventional cytogenetics, FISH, and RT-PCR to detect genetic changes in 70 children with ALL.Soszynska K et al

Summary

Atlas Image
Partial karyotypes showing the chromosomal translocation t(X;11)(q22;q23).

Citation

Adriana Zamecnikova

t(X;11)(q22;q23) KMT2A/?

Atlas Genet Cytogenet Oncol Haematol. 2011-02-01

Online version: http://atlasgeneticsoncology.org/haematological/1573/t(x;11)(q22;q23)

External Links