OBJECTIVETo analyze the expression of genes from chromosomal region 22q11.2 and assess the association between mutation(s) of particular gene(s) from this region and malformations of the urinary system.

METHODSExpression of rat homologs of 33 genes from above region was determined in kidney tissues derived from rats of different fetal development ages (E13, E15, E19) and adulthood with reverse transcriptase-PCR. Potential mutation(s) in candidate gene SNAP29, whose expression pattern appeared to be unique, was screened in 44 patients and 220 normal controls with PCR-single strand conformation polymorphism (SSCP). Suspected positive regions were sequenced to verify the mutations.

RESULTSNine genes showed no expression throughout the whole development process; 18 genes with various expression levels showed continuous expression from the beginning of development; 6 genes only expressed for a short time, among which SNAP29 was selected for mutation screening. Upon sequencing, three mutations were identified from the 44 patients, including a G to A transition (GAG to AAG) in exon 2, and two A to G transitions (AGC to GGC) in exon 3.

CONCLUSIONThrough systematic analysis of the expression of genes from chromosomal region 22q11.2, the SNAP29 gene was found to have a potential role in the development of genitourinary system. Two missense mutations were identified in three patients. These included one in exon 2 (featuring cryptorchidism), and the other in exon 3 (featuring cryptorchidism and hypospadia). Neither of the mutations was found in the normal controls. The results suggested that mutation(s) of gene(s) from chromosomal region 22q11.2 may play an important role in the genesis of genitourinary malformations.