SUN-008 Loss of Antimullerian Hormone Immunoreactivity Due to a Homozygous AMH Gene Mutation Rs10417628 in a Woman with Classical Polycystic Ovary Syndrome
Authors: Hoyos Luis R , Visser Jenny A , McLuskey Anke , Chazenbalk Gregorio D , Grogan Tristan R , Dumesic Daniel A 
Published: May 2020

Anti-Müllerian hormone (AMH), an inhibitor of primordial/small antral follicle development and Leydig cell androgen synthesis in mice, could exaggerate the polycystic ovary syndrome (PCOS) phenotype, given reports of PCOS-specific AMH loss-of-function mutations (1–3). This report describes a normal-weight PCOS woman with severely reduced AMH levels (index PCOS woman). It examines the molecular basis for her reduced serum AMH levels and also compares her endocrine characteristics to similar-weight PCOS women with detectable AMH. Twenty normo-androgenic ovulatory (control) and 13 age- and body mass index-matched PCOS women (19–35 years; 19–25 kg/m2) underwent transvaginal sonography and serum hormone measures. Wilcoxon rank-sum test compared clinical features of control and PCOS women with detectable AMH, which were then individually ranked by magnitude in all PCOS women. DNA analysis was performed by PCR amplification with direct gene sequencing. The identified mutation was introduced in hAMH-expression plasmids for functional analysis of AMH processing in HEK293 cells by Western blot and ELISA (pico-AMH assay, Ansh Labs, Webster, TX), and for bioactivity in KK-1/AMHR2 cells using a luciferase reporter. Unpaired t-test compared AMH-induced luciferase activity between wild type and mutant AMH. A homozygous AMH gene mutation rs10417628 involving a single base pair substitution in exon 5 (NG_012190.1:g.7705C&gt;T, p.(Ala515Val)) was identified in the index PCOS woman. PCOS women with detectable AMH had higher serum AMH (10.82 [6.74–13.40] ng/mL, Median [IQR]), total/free testosterone (T) (total T: 55.5 [49.5–62.5] ng/dL; fT: 5.65 [4.75–6.6] pg/mL) levels and greater total antral follicle numbers (AFNs) (46 [39–59] follicles) than controls (AMH: 4.03 [2.47–6.11] ng/ml; total T: 30 [24.5–34.5] ng/dL; fT: 2.2 [1.8–2.45] pg/mL; AFNs 16 [14.5–21.5] follicles, P&lt;0.05, all values), along with a trend toward LH hypersecretion (P=0.06). The index PCOS woman with the lowest AMH levels (0.1 ng/ml) did not have the highest serum total T/fT (total T: 89 ng/dL; fT: 7 pg/mL,) or LH levels nor the greatest AFN (43 follicles). In vitro analysis of cells expressing hAMH-515Val or hAMH-515Ala showed that hAMH515-Val, in contrast to hAMH515-Ala, was undetectable and severely reduced in the pico-AMH assay in cell lysates and supernatants, respectively. AMH protein processing and AMH-induced luciferase activity, however, did not differ between hAMH515Val and hAMH515Ala. Thus, homozygous AMH mutation rs10417628 in a PCOS woman can impair serum AMH immunoreactivity without affecting AMH bioactivity, perhaps because of conformational changes from the mutation that only interfere with its immunodetection but not its function. References: 1. Teixeira J, et al. Endocrinology 1999;140:4732 2. Gorsic LK et al. JCEM 2019;104:2855 3. Broekmans FJ, et al. Trends Endocrinol Metab 2008;19:340