MON-235 Bone Morphogenic Protein Receptor Variants: A New Cause of Primary Ovarian Insufficiency

Primary ovarian insufficiency (POI) is a major cause of infertility. This disease is characterized by amenorrhea with an increase in gonadotropin levels and affects 1% of women before the age of 40. POI may be the result of a broad spectrum of disorders caused by two main mechanisms: abnormal follicular development and follicle depletion due to a defect in their formation or an aberrantly rapid depletion of the stock. Although the majority of cases are idiopathic, POI can be trigged by autoimmune disease, infectious agents, iatrogenic effects, or genetic causes. It may also be part of syndromic diseases such as Turner, Fragile-X or Blepharophimosis Ptosis Epicanthus Inversus syndrome. However, in the majority of cases, the cause of POI is unknown suggesting that new causative genes are yet to be discovered. We conducted a Whole Exome Sequencing on 69 Caucasian women with sporadic POI and performed a bioinformatics analysis on a specific subset of 420 coherent candidate genes1. We identified variations in about fifty genes potentially linked to POI, including new genes never described to be associated with the diseases aetiology, such as AuTophagy related Genes (ATG)2, KHDRBS1 gene encoding an RNA-binding protein3, NOTCH2 gene4... We also found variants in genes encoding Bone Morphogenetic Protein Receptors (BMPR1A and BMPR1B) in three patients. These receptors bind ligands of TGFβ superfamily. Mutations of members of this family (e.g. BMP15, GDF9) are known to be involved in the etiology of POI. BMPR encode transmembrane receptors with serine-threonine kinase activity expressed in the granulosa cells of growing follicles. Missense variations, located in the kinase domain of both receptors 1A and 1B, are predicted to be deleterious in silico. We studied the signaling pathway of these receptors: SMAD proteins phosphorylation, measurement of their transcriptional activity and expression of specific target genes and showed that they are deleterious. Bmpr1a -/- and Bmpr1b-/- mouse models develop infertility due to a reduced spontaneous ovulation and compromised cumulus expansion respectively, indicating that both genes play a crucial role in fertility. Altogether, our study describes the first BMPR1A and 1B mutations associated with POI and increases the number of genes formally implicated as being responsible for this condition. 1Patiño LC, Beau I, Carlosama C, Buitrago JC, González R, Suárez CF, Patarroyo MA, Delemer B, Young J, Binart N, Laissue P. Hum Reprod. 2017; 32(7):1512-1520. 2Delcour C, Amazit L, Patino L, Magnin F, Fagart J, Delemer B, Young J, Laissue P, Binart N, Beau I. Genet Med. 2018 (in press) 3Carlosama C, Patiño L, Beau I, Morel A, Delemer B, Young J, Binart N, Laissue P. Clin Endocrinol (Oxf). 2018 (in press) 4Patiño LC, Beau I, Morel A, Delemer B, Young J, Binart N, Laissue P. Hum Mutat. 2018 (in press)