Ανίχνευση μεταλλάξεων στο γονίδιο KAL, στο γονίδιο της GnRH, στο γονίδιο του υποκινητή της GnRH και στο γονίδιο του υποδοχέα της GnRH σε ασθενείς με ανεπάρκεια GnRH

Abstract

The syndrome of GnRH insufficiency is due to a functional deficit of GnRH production or secretion in the hypothalamus resulting in the loss of pulsatile secretion of GnRH. This deficiency leads to a complete or partial arrest of sexual maturation and infertility. Patients with no further anomalies are referred as having Idiopathic Hypogonadotropic Hypogonadism (IHH) and when accompanied with anosmia, it is called Kallmann syndrome. The aim of this study was to identify mutations in the KAL gene, the GnRH gene, the GnRH receptor gene and their promoters in patients with GnRH insufficiency, the prevalence in the Greek population and the relevance between the genotype and individual phenotype of these patients. The study included thirty eight (38) patients with GnRH insufficiency, twelve patients (12) with Kallmann syndrome and twenty six patients with IHH (13 male and 13 female). Detection was carried out by isolation of genomic DNA from whole blood, which was used as a template for PCR amplification and finally, cycle sequencing analysis of all exons spanning the entire coding regions of the genes. No mutations were found in the KAL gene, whereas in patients with IHH, no mutations were identified in transcription factor binding sites of the promoters of the GnRH and GnRH receptor gene. In the GnRH gene of five (5) patients with IHH a natural polymorphism was identified in codon 16 (gc Trp16Ser). In the GnRH receptor gene a novel mutation was found in codon 146, resulting in substitution of proline with serine identified in two sisters harboring this mutation in hetrozygosity. The two sisters and a male patient with IHH with normal gene sequencing were found to be resistant to GnRH action. Resistance to GnRH is particularly rare among IHH patients. One might hypothesize, that these patients ought to have inactivating mutations in their receptor gene. However such a defect was not found, therefore making these patients an ideal clinical phenotype of an aberration in signal transduction pathway or in transcriptional factors which regulate the expression of the GnRH receptor. A common pathogenesis for KS and schizophrenia had been proposed, based on shared pathologies of these two disorders. The gene for the X-linked form of KS (known as KAL) has been implicated in the genetic pathogenesis of schizophrenias, although no such clinical associations have ever been reported. An additional aim of this study was to identify any pshychopathologies in these patients. One of our patients with KS also developed schizophrenia but no mutations were identified in all 14 exons of the KAL gene.