RESUMEN
El síndrome de poliquistosis ovárica (PCOS) es un desorden endocrino-metabólico de naturaleza multifactorial, con una marcada predisposición genética, que afecta al 6% de las mujeres en edad reproductiva. Se caracteriza por la presencia de hiperandrogenismo, oligo-anovulación y ovarios poliquísticos. Entre los genes candidatos se encuentran aquellos que codifican para enzimas que actúan en la síntesis de andrógenos. Dos de los genes candidatos son el CYP17 y el CYP11alfa que codifican para la 17alfa hidroxilasa (P45017alfa) y para el P450scc (colesterol side chain cleavage) respectivamente. Los polimorfismos en estos genes están asociados al desarrollo del fenotipo hiperandrogénico. Nuestro objetivo fue analizar las frecuencias alélicas de los polimorfismos de los dos genes mencionados en población con PCOS, compararla con población normal y analizar la relación de cada variante alélica con el fenotipo hiperandrogénico correspondiente. Se analizaron 65 pacientes y 58 controles sanos en los que se determinaron niveles de testosterona y frecuencia de polimorfismos en los genes mencionados. Se observó una diferencia estadísticamente significativa cuando se asoció el grupo de mayor nivel de androgenemia con la presencia del genotipo A2/A2 del gen CYP17, y se hallaron mayores niveles de andrógenos circulantes en las pacientes con PCOS portadoras del alelo 216- del gen CYP11alfa. Nuestros resultados sugieren que ambos alelos juegan un rol menor en el desarrollo de PCOS y podrían ser considerados como potenciales marcadores de riesgo genético para el desarrollo del fenotipo hiperandrogénico.
The polycystic ovary syndrome (PCOS) is a heterogeneous multifactorial endocrine metabolic disorder with genetic predisposition affecting 6% of women in the reproductive age. This syndrome is characterized by the presence of oligo-anovulation, hyperandrogenism and polycystic ovaries. Several genes have been postulated as responsible for the etiology of this disorder. Among these genes are those encoding the enzymes involved in the ovarian androgen biosynthesis. Two of the candidate genes are the CYP17 and the CYP11alpha, encoding the 17-alpha-hydroxylase (P45017alpha) and the cholesterol side chain cleavage (P450scc) respectively. The polymorphisms of these genes are linked to the development of an hyperandrogenic phenotype. The aim of this work was to analyze the allelic frequencies of such polymorphisms in a cohort of women with PCOS and to compare them with those of healthy women. Furthermore, the correlation between each allelic variant and the corresponding hyperandrogenic phenotype was also assessed. Therefore, 65 patients and 58 age matched healthy controls were analyzed. The serum levels of testosterone and the frequency of each polymorphism were determined. When the PCOS population was analyzed, a significant statistical difference was found when relating the group with the highest androgenemia level with the presence of A2/A2 genotype of CYP 17 gene, and a higher level of circulating androgen was found in PCO women carrying the 216- allele of CYP11alpha gene (that did not reach statistical significance). Our results suggest that both alleles play a minor role in the development of PCOS and could be a genetic risk marker of the hyperandrogenic phenotype.
Asunto(s)
Femenino , Humanos , Enzima de Desdoblamiento de la Cadena Lateral del Colesterol/genética , Hiperandrogenismo/genética , Síndrome del Ovario Poliquístico/genética , Polimorfismo Genético/genética , /genética , Andrógenos/análisis , Andrógenos/farmacocinética , Disponibilidad Biológica , Estudios de Casos y Controles , Marcadores Genéticos/genética , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Testosterona/análisis , Testosterona/farmacocinéticaRESUMEN
In hiperandrogenic states an abnormal pattern of LH secretion in women is observed, which is presumed to result from a direct action of androgen or its conversion to estrogen. Two strategies are available to study the effect of testosterona on LH secretion.One involves the use of non-steroidal compounds that block the negative feedback actions of endogenous androgens by binding to androgen receptors; the other consists only in the administration of androgens. Following these two strategies, we first studies the pulsatile gonadotrophin secretion in hyperandrogenic women, following flutamide administration, a specific androgen receptor blocker. Flutamide treatment was followed by a decrease in LH pulse amplitude and mean LH concentrations, demonstrating that androgen receptor blockade reduces LH secretion in hyperandrogenic women. To establish the level at which the androgen effect is exerted, we further studied the acute effect of testosterone (hyperandrogenic levels) and the blockade of its receptor on LH secretion in patients with severe hypothalamic deficiency treated with pulsatile GnRH (GnRHp). LH pulse profiles were assessed under GnRHp treatment alone, during testosterone and during testosterone and flutamide administration. Testosterone increased LH secretion and LH pulse amplitud. Flutamide significantly reverted the LH increase induced by testosterone.These results strongly suggest that testosterone in the hyperandrogenic female range, may facilitate LH secretion by the pituitary, effect that is reserved by the blockade of the androgen receptor