LDB2 locus disruption on 4p16.1 as a risk factor for schizophrenia and bipolar disorder

Clinical and genetic analysis of two phenotypically normal families carrying 4p16.1 microduplications

OBJECTIVE

To help determine the pathogenicity of 4p16.1 microduplications, we reported two asymptomatic families carrying this variation.

CASE REPORT

We present the prenatal diagnosis and genetic analysis of two normal families with 4p16.1 microduplications.

CONCLUSION

This paper highlights two families with clinically asymptomatic 4p16.1 microduplications that assisted in determining the pathogenicity of this fragment. The findings can be used as a reference for genetic counseling in cases of similar abnormalities encountered during future prenatal diagnosis.

Cooperation of LIM domain-binding 2 (LDB2) with EGR in the pathogenesis of schizophrenia

Genomic defects with large effect size can help elucidate unknown pathologic architecture of mental disorders. We previously reported on a patient with schizophrenia and a balanced translocation between chromosomes 4 and 13 and found that the breakpoint within chromosome 4 is located near the LDB2 gene. We show here that Ldb2 knockout (KO) mice displayed multiple deficits relevant to mental disorders. In particular, Ldb2 KO mice exhibited deficits in the fear-conditioning paradigm. Analysis of the amygdala suggested that dysregulation of synaptic activities controlled by the immediate early gene Arc is involved in the phenotypes. We show that LDB2 forms protein complexes with known transcription factors. Consistently, ChIP-seq analyses indicated that LDB2 binds to > 10,000 genomic sites in human neurospheres. We found that many of those sites, including the promoter region of ARC, are occupied by EGR transcription factors. Our previous study showed an association of the EGR family genes with schizophrenia. Collectively, the findings suggest that dysregulation in the gene expression controlled by the LDB2-EGR axis underlies a pathogenesis of subset of mental disorders.