Poster Sessions

GENO -20

Eric Levens

E. D. Levens, X. Xu, P. J. Munson, L. M. Nelson, A. H. DeCherney, L. K. Nieman

Novel target genes may be responsible for SRY positive sex-reversal: the results of an exon expression analysis

Objective: Normal male sexual development depends largely upon two determinant factors: the sex-determining region of the Y chromosome, SRY, and autosomal transcription factors down-stream of SRY. SRY directs several down-stream genes resulting in normal male sexual development. However, it is unknown which genes may be disrupted in SRY+, 46 XY sex-reversed females accounting for the lack of masculinization. We hypothesized that the transcript profile of these subjects may be different from normal males and females, and that by evaluating this profile, we might identify new genes responsible, in part, for male sexual differentiation. Design: Exon-level gene expression profiling studies. Materials and Methods: After obtaining informed consent, total RNA isolated from PBMCs from a confirmed SRY+, 46 XY sex-reversed female and 2 normal 46, XX females and 2 normal 46, XY males was subjected to the Affymetrix GeneChip® Human Exon 1.0 ST Array. Autosomal genes demonstrating 8-fold differential expression and Y chromosome genes demonstrating 2-fold differential expression in the patient compared to controls were analyzed using JMP (SAS; Cary, NC). Results: Compared to control males, SRY and other Y-chromosome genes were normally or over-expressed in the patient, suggesting that the Y chromosome was transcriptionally active. However, RBMY2FP, a RNA-binding protein implicated as an azoospermia factor, was under-expressed. The patient under-expressed 104 autosomal genes compared to normal males, suggesting that these genes may be required for normal male development. Most notable were TDGF1, a critical gene in developmental regulation, and ASTN1, which associates with CD81 on the surface of oocytes and its under-expression has been linked to reduced fertility in mice. Comparing the patient to normal females identified under-expression of MYOM2 and PRKAR2B, suggesting an endogenous hypogonadal, hypoandrogenic environment. Conclusions: We report one of the first transcript profiling studies of SRY+ 46, XY sex-reversed females. Normal SRY transcript levels were noted, supporting the conclusion that genes down-stream of SRY may be disrupted and may be important genes in sexual differentiation. TDGF1 and ASTN1, which have been implicated in development and fertility, may be targets of SRY. Additionally, RBMY2FP, on the Y chromosome, was under-expressed in our patient and remains a gene of interest. These genes might be putative novel targets of SRY.