Decreased expression of genes associated with memory and x-linked mental retardation in boys with non-syndromic cryptorchidism and high infertility risk.

An elevated odds ratio for low IQ has been found for cryptorchid boys. Furthermore, poor school performance has been observed in cryptorchid boys with impaired mini-puberty. Gene expression analysis, qPCR and immunohistology were performed on testicular biopsies from 7 boys who underwent orchiopexy and had testicular histology typical of a high risk of infertility (HIR). The results were compared with 12 biopsies from cryptorchid boys with a low risk for developing infertility. The following genes associated with mental retardation were identically expressed: GDI1, OPHN1, PAK3, ARHGEF6, IL1RAPL, ACSL4, MECP2, RPS6KA3, ARX, and ATRX. However, boys in the HIR group had low or no expression of EGR4, FMR2 (AFF2) and VCX3A. In conclusion, impaired expression of genes known to encode proteins involved in signaling pathways that regulate cytoskeletal organization, synaptic vesicle transport and the establishment of connections between neuronal cells may contribute to reduced intellectual and cognitive functioning in infertile cryptorchid males.

Testicular gene expression in cryptorchid boys at risk of azoospermia.

Despite timely and successful surgery, 32% of patients with bilateral and 10% with unilateral cryptorchidism will develop azoospermia. Cryptorchid boys at risk of azoospermia display a typical testicular histology of impaired mini-puberty at the time of the orchidopexy. During mini-puberty increased gonadotropin and testosterone secretion stimulate transformation of gonocytes into Ad spermatogonia. In the azoospermia risk group this transformation is to a great extent impaired. This study aimed to analyze data on whole genome expression signatures of undescended testes at risk of developing azoospermia. Twenty-three testicular biopsies from 22 boys were analyzed (19 testes from 18 boys with cryptorchidism and 4 contralateral descended testes from patients with testicular agenesis). Expression profiling identified 483 genes not or under-expressed in the azoospermia risk group compared with the control and low risk for azoospermia (LAZR) groups. Annotated loci were associated with spermatogenesis. Other significant genes were cellular defense response genes and hormone-controlled loci involved in spermatogenesis. Some genes transcribed in normal adult meiotic and post-meiotic germ cells are activated in healthy juvenile Ad spermatogonia. Thus, molecular events initiating the testicular expression program at the onset of puberty and maintaining it during adulthood occur very early in prepubertal testes. This molecular event is to a great extent impaired in the high risk for azoospermia (HAZR) group lacking Ad spermatogonia (stem cells for spermatozoa) indicating impaired mini-puberty.

Deficient expression of genes involved in the endogenous defense system against transposons in cryptorchid boys with impaired mini-puberty.

Mini-puberty is the period between 30 and 80 days after birth when testosterone and gonadotropin surges occur in male infants to induce the transformation of gonocytes into adult/dark spermatogonia. Cryptorchid boys with impaired mini-puberty develop infertility despite timely and successful surgical treatment. The decreased germ cell count found in this group of boys could be the result of uncontrolled transposon activity inducing genomic instability and germ cell death. A genome-wide analysis of 18 cryptorchid and 4 control testes was performed with Affymetrix chips. We found that 5 of 8 genes that are important for transposon silencing were not expressed in the high azoospermia risk group of cryptorchid boys but were expressed in the low azoospermia risk and control groups. Two genes, CBX3 and DNMT1, were equally expressed in all 3 groups. Impaired expression of the DDX4, MAEL,MOV10L1, PIWIL2, PIWIL4, and TDRD9 genes in the group of cryptorchid boys at high risk of infertility indicates that gene instability induced by impaired expression of transposon silencing genes contribute to the development of azoospermia. Intact mini-puberty appears to be essential for the development of the endogenous defense system mediated by transposon silencing.

Decreased expression of FGFR1, SOS1, RAF1 genes in cryptorchidism.

BACKGROUND: In recent years, several genes were found to be involved in the process of epididymo-testicular descent, the most frequently cited ones include INSL3, HOXA10, GNRHR, and KAL1. In this study, we analyzed the differences in gene expression profiles between cryptorchid and descended testes. In particular, we analyzed expression of all recently published genes known to be associated with undescended testis. PATIENTS AND METHODS: Twenty-two testicular biopsies from 18 boys were analyzed. We analyzed gene expression in 16 cryptorchid and 6 descended testes using Affymetrix Human Genome U133 Plus 2.0 GeneChips, and validated the results with qPCR. RESULTS: 3,688 transcripts were differentially expressed with an adjusted p value of <0.05 and a change of at least 1.5-fold. The list contained 1,866 downregulated and 1,822 upregulated transcripts in the cryptorchid testes. A novel observation in our study was that the fibroblast growth factor receptor 1 gene (FGFR1) and its mediators SOS1 and RAF1 were expressed less in undescended testes. CONCLUSION: Based on our results, it is possible that a subtle dysfunction (expression) of the FGFR1, SOS1 and RAF1 genes is involved in the development of the most common male reproductive tract disorder - unilateral or bilateral cryptorchidism.

EGR4 is a master gene responsible for fertility in cryptorchidism.

The purpose of early medical or surgical treatment of boys with undescended testes is to prevent the development of infertility. However, early and successful surgery cannot prevent infertility in cryptorchid boys who lack type A dark (Ad) spermatogonia. The aim of this study was to compare the gene expression pattern of patients with completed transformation of gonocytes into Ad spermatogonia, associated with low infertility risk, with patients that had failed to undergo this process and had a high infertility risk. Genes expressed in the 16 cryptorchid testes were estimated using Affymetrix whole-genome microarray and compared to the expression profiles from four contralateral gonads of boys with unilateral testicular agenesis. Whole-genome expression profiling showed that boys in the high infertility risk group according to testicular histology, showed decreased or lack of expression of most of the genes essential for hypothalamo-pituitary-testicular axis function relative to low or intermediate risk group as well as controls. In particular, EGR4, which is involved in regulating the secretion of luteinizing hormone, was virtually not expressed. Thus, we found multiple differences in gene expression between the high and low infertility risk groups, confirming the importance of an intact hypothalamo-pituitary testicular axis and EGR4 in fertility development.