Short communication on t t(6;20)(q13;q12) LMBRD1/CHD6, with data on clinics, and the genes implicated

De, Braekeleer E

De, Braekeleer M

Douet-Guilbert, N

Guéganic, N

Morel, F

Tous, C

Atlas of Genetics and Cytogenetics in Oncology and Haematology

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Leukaemia Section 
Short Communication 
 
Atlas Genet Cytogenet Oncol Haematol. 2014; 18(12) 954 
Atlas of Genetics and Cytogenetics 
in Oncology and Haematology 
INIST-CNRS 
 
OPEN ACCESS JOURNAL 
t(6;20)(q13;q12) LMBRD1/CHD6 
Nathalie Douet-Guilbert, Etienne De Braekeleer, Corinne Tous, Nadia Guéganic, Frédéric 
Morel, Marc De Braekeleer 
Cytogenetics Laboratory, Faculty of Medicine, University of Brest, France (NDG, ED, CT, NG, FM, 
MD) 
 
Published in Atlas Database: April 2014 
Online updated version : http://AtlasGeneticsOncology.org/Anomalies/t0620q13q12ID1678.html 
DOI: 10.4267/2042/54378 
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 France Licence. 
© 2014 Atlas of Genetics and Cytogenetics in Oncology and Haematology 
 
Abstract 
Short communication on t t(6;20)(q13;q12) 
LMBRD1/CHD6, with data on clinics, and the 
genes implicated. 
Clinics and pathology 
Disease 
Myelodysplastic syndrome/myeloproliferative 
disorder (MDS/MPD) in transformation (Acute 
myelocytic leukemia - AML) 
Epidemiology 
No cases registered in the Mitelman database. 
Clinics 
A 78-year-old woman seen because of worsening of 
cytopenias two years following diagnosis of 
MDS/MPD. No further investigations. 
Evolution 
Patient deceased soon after diagnosis of AML. 
Cytogenetics 
Note 
The t(6;20)(q13;q12) involves two genes, the 
LMBRD1 and CHD6 genes, that have never been 
shown to form a fusion gene. 
Cytogenetics morphological 
t(6;20)(q13;q12) is identified by banding 
cytogenetics. 
 
 
RHG banding showing chromosomes 6 and 20 and the 
derivatives der(6) and der(20). 
Cytogenetics molecular 
To determine the position of the breakpoints on 
chromosomes 6 and 20, BACs located in the bands 
of interest were used as probes in FISH 
experiments. Analysis with RP11-359N1 showed 
that one signal hybridized to the normal 
chromosome 6, and the other split and hybridized to 
both der(6) and der(20). Analysis with RP11-
257H6 showed that one signal hybridized to the 
normal chromosome 20, and the other split and 
hybridized to both der(6) and der(20). Co-
hybridization with both BAC clones showed two 
fusion signals. RP11-359N1 contains the LMBRD1 
gene and RP11-257H6 the CHD6 gene. 
t(6;20)(q13;q12) LMBRD1/CHD6 Douet-Guilbert N, et al. 
 
 
 
 
 
Atlas Genet Cytogenet Oncol Haematol. 2014; 18(12) 955 
 
FISH with BACs RP11-359N1 (spectrum green, located in 6q13 and containing LMBRD1) and RP11-257H6 (spectrum orange, 
located in 20q12 and containing CHD6) showing co-hybridization. 
 
 
Genes involved and 
proteins 
LMBRD1 
Location 
6q13 
Note 
Mutations in the LMBRD1 gene is responsible for 
methylmalonic aciduria and homocystinuria type 
cblF (autosomal recessive disorder). It is a disorder 
of cobalamin metabolism characterized by 
decreased levels of the coenzymes 
adenosylcobalamin and methylcobalamin due to 
accumulation of free cobalamin in lysosomes, thus 
preventing its conversion to cofactors. 
Clinical features include poor feeding, failure to 
thrive, developmental delay, stomatitis, glossitis, 
seizures, macrocytic anemia, neutropenia, 
thrombocytopenia and methylmalonic aciduria 
responsive to vitamin B12. 
DNA/RNA 
The LMBRD1 gene contains 15 exons, spanning 
115 kb. Three transcripts (splice variants) are 
known, two being protein coding. 
Protein 
The protein has 540 amino acids (61.4 kDa) and 
localizes to the lysosome membrane. It contains 
nine transmembrane helices and six putative 
glycosylation sites with an N terminus in the 
lysosomal interior and a cytoplasmatic C terminus. 
It is a probable lysosomal cobalamin transporter, 
being required to export cobalamin from 
lysosomes, which in turn allows its conversion to 
cofactors.  
It also appears to play a key role in mediating and 
regulating the endocytosis of the insulin receptor. 
Isoform 3 coding the nuclear export signal 
interacting protein (NESI) may play a role in the 
assembly of hepatitis delta virus. 
CHD6 
Location 
20q12 
Note 
The CHD6 gene, located 403 kb centromeric to 
STS marker D20S108 is constantly deleted in MDS 
and MPD associated with del(20q) or ider(20q). 
DNA/RNA 
The CHD6 gene contains 37 exons of which 36 are 
coding, spanning 216 kb. Nine transcripts are 
known. 
Protein 
The gene encodes a member of the SNF2/RAD54 
helicase protein family. The protein has 2715 amino 
acids (305 kDa) and localizes to the nucleus. It 
contains two chromodomains, a helicase domain, 
and an ATPase domain.  
The protein is thought to be a core member of one 
or more of chromatin remodelling complexes. It 
may function as a transcriptional repressor.  
It is involved in the cellular repression of influenza 
virus replication and in transcriptional repression of 
papillomavirus. 
t(6;20)(q13;q12) LMBRD1/CHD6 Douet-Guilbert N, et al. 
 
 
 
 
 
Atlas Genet Cytogenet Oncol Haematol. 2014; 18(12) 956 
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This article should be referenced as such: 
Douet-Guilbert N, De Braekeleer E, Tous C, Guéganic N, 
Morel F, De Braekeleer M. t(6;20)(q13;q12) 
LMBRD1/CHD6. Atlas Genet Cytogenet Oncol Haematol. 
2014; 18(12):954-956. 


t(6;20)(q13;q12) LMBRD1/CHD6

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