ESPE Abstracts

Background: The hCG stimulation test is a valuable method for assessing androgen production but there is a need to explore its utility in assessing androgen responsiveness and long-term prognosis.

Objective and hypothesis: Our aim was to explore the effect of hCG stimulation on the peripheral transcriptome in boys undergoing investigation for DSD.

Method: Thirteen boys undergoing investigation for 46,XY DSD received i.m. hCG 1500 U on 3 consecutive days and had blood sampling on D0 and D3. Testosterone was measured and phenotype recorded. RNA was extracted from peripheral blood mononuclear cells on the Qiacube using RNA Blood Mini Kit with an incorporated DNase step. Microarray hybridisation was performed on 13 paired samples using the Affymetrix Human Transcript Array (HTA) 2.0. Gene expression fold change was calculated and corrected for those boys who did not have a testosterone rise.

Results: Median age (range) at test was 0.83 years (0.18–11.23) with a median external masculinisation score of 9 (6–11). Three boys had isolated proximal hypospadias, six had bilateral undescended testes, and four had a combination of hypospadias, impalpable testes or micropenis. Median pre and post hCG testosterone were <0.5 nmol/l (<0.5–6) and 7.9 nmol/l (<0.5–31.5) respectively. Median fold change of testosterone was 6.8 (1–26.6) and 3 (23%) boys did not demonstrate a testosterone rise (non-responders). Median AMH in the responders was 688 pmol/l (24, 1628) and in the non-responders was <4 pmol/l (<4256). 8 (80%) of the responders and 2 (66%) of the non-responders had AR mutation analysis performed and had no variant detected. When corrected for gene expression changes in the non-responders, all ten of the responders demonstrated a 20% or greater increase in the expression of piR-37150, a non-coding piwi-interacting RNA. 8 (80%), 6 (60%), and 4 (40%) of the responders demonstrated a 30, 40, and 50% rise respectively in a total of five piRNAs.

Conclusion: The identification of a dynamic peripheral transcriptome that is associated with an androgen response following hCG stimulation extends the potential value of this clinical test. The role of piRNAs as a diagnostic and prognostic marker of gonadal function needs further investigation.