Del/ins polymorphism in DGCR6 gene in chromosome 22 and schizophrenia

The chromosome 22q11 region is a focus for loci of schizophrenia, because DiGeorge syndrome caused by deletion of this region can be accompanied by a schizophrenic psychosis, which was designated as 22q11 deletion syndrome-schizophrenia. We examined the DGCR6 gene, an potential adhesion receptor protein gene and involved in migration of neural crest cells, located in the critical region. BLAST search revealed that DGCR6 consists of at least 5 exons and 4 introns. We found a novel polymorphism 9-bp del/ins in intron 1 at 7 bp from end of exon 1. Allele frequency of Ins and Del alleles were 93.1 % and 6.9 % in normal Japanese (N=102), respectively. Schizophrenic patients (N=116) showed higher frequency of Del allele as 10. 3 %, but it was not significant. As to subcategory, hebephrenic type of schizophrenia (N=39) showed a significantly higher frequency of the Del allele as 15.4 % (p=0.027). The patients with family history, although only 19, showed significantly and the highest frequency of the Del allele as 18.4 %. The present study found the first evidence of an association between schizophrenia and the DGCR6 gene.