Mutational analysis of the genes encoding RFRP3 and its receptor in patients with GnRH-dependent pubertal disorders

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: SAT 134-163-GnRH & Gonadotroph Biology & Signaling
Bench to Bedside
Saturday, June 15, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board SAT-149
Cristiane Jeyce de Lima*1, Sarah Caixeta1, Erica Lima1, Emilie Zingler2, Carla Capanema1, Larissa Dias1, Gabriela Vogado1, Olivia Laquis de Moraes3, Ana Claudia Latronico4 and Adriana Lofrano Alves Porto5
1Universidade de Brasília, 2Universidade de Brasilia, Brasilia, DF, Brazil, 3Universidade de Brasilia, Brasilia, Brazil, 4University of Sao Paulo, Sao Paulo-SP, Brazil, 5University of Brasilia, Brasilia DF, Brazil
INTRODUCTION: Gonadotropin-releasing hormone is the main stimulator of gonadotropin secretion, but many other neuropeptides are involved in the regulation of reproductive function. In 2009, the orthologue of avian gonadotropin-inhibitory hormone (GnIH), called RFRP-3, was identified in the human hypothalamus and pituitary. However, its physiological roles are still obscure, especially in humans. We aimed to investigate the occurrence of variants in the genes encoding RFRP-3, the human GnIH ortholog, and its receptor, GPR147, in a cohort of Brazilian patients with idiopathic GnRH-dependent pubertal disorders. METHODS: One hundred and thirty one patients were studied: 51 with normosmic isolated hypogonadotropic hypogonadism (nIHH) and 80 with idiopathic central precocious puberty (CPP). Genomic DNA was extracted from peripheral blood leucocytes and the entire coding region of the genes encoding RFRP and GPR147 (NPVF and NPFFR1, respectively) were amplified and sequenced.The identified variants were analyzed in sillico as to their predicted functional effects (PolyPhen software). RESULTS: Two previously known variants were found in the NPVF gene, p.Ile71_Lys72 and p.Pro128=. Two nIHH patients carried the homozygous in-frame deletion p.Ile71_Lys72, whilst none in the CPP group. In the NPFFR1 gene, 12 known variants were found, 7 of them were synonymous. Among the other 5 missense substitutions detected, only (p.Ile145Leu) is predicted to be damaging. This variant was present in homozygous state in 4 patients with CPP and none of the nIHH patients, although its combined frequency was similar in both groups. A novel variant (p.Ser88Asn) was identified in heterozygozity in a patient with nIHH, predicted to be damaging. DISCUSSION: Recent studies showed that human RFRP-3 is an active decapeptide derived from the cleavage of a precursor polypeptide. The p.Ile71_Lys72 deletion results in the loss of an isoleucine adjacent to a predicted proteolytic site. Two probably damaging missense mutations in the gene encoding GPR147 (p.Ile145Leu and p.Ser88Asn) were identified. CONCLUSIONS: Our preliminary findings reveal the existence of some variants in the RFRP-3 and GPR147 genes that might be damaging. A possible pathogenic role of the RFRP-GPR147 pathway in the development of pubertal disorders in humans cannot be ruled out yet. Mutational screening in a control group and functional in vitro studies with selected variants are necessary for further clarifying this issue.

Nothing to Disclose: CJDL, SC, EL, EZ, CC, LD, GV, OLDM, ACL, ALAP

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Sources of Research Support: Conselho Nacional de Pesquisa (CNPq) - Brazil - Grant to ALAP: 477016-2011