Avalia§£o gen©tica do homem inf©rtil

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Avanos na Infertilidade Masculina - o que voc precisa saber

Avaliao Gentica do Homem Infrtil

Esteves, 1

Sandro EstevesDiretor, ANDROFERTCampinas, SP

Congresso Brasileiro de Urologia Florianpolis 2011Curso de Ps-graduao Avaliao em Infertilidade Masculina Contedo da AulaEsteves, 22Base Gentica Fertilidade Masculina

Hamada, Esteves, Agarwal: Genetics and Male Infertility. In: Dubey A [ed]. Infertility: Management and Treatment, Jaypee Med. Pub., In pressHuman genome is composed of 23 pairs of nuclear chromosomes, 22 pairs are autosomes and one pair of sex chromosome (XX in female and XY in male). Bodys cells are two types: somatic cells and germ cells (gametes). While somatic cells (non-reproductive cells) are diploid (46 chromosome) and forms the basic units in organ tissues, germ cells (eggs and sperm) are haploid (23 chromosomes and only present in the ovaries and testes respectively.

Chromosomes are composed of chromatin which is a complex of unbroken long, double stranded and tightly wound DNA which carries the genes, and proteins which help in packing of chromosome in the nucleus.Base Gentica Fertilidade Masculina

Hamada, Esteves, Agarwal: Genetics and Male Infertility. In: Dubey A [ed]. Infertility: Management and Treatment, Jaypee Med. Pub., In pressGenes are stretches of DNA sequence that encode specific functions such as synthesis of protein through mRNA transcription or synthesis of functional RNA. Human genome contains about 40 million genes.

Structurally, genes usually consist of coding regions called exons interrupted by at least one or several non-coding segments called introns. Then by process of splicing, introns are removed from the specifically synthesized RNA and exons are joined together to form mRNA coding for synthesis of specific protein.

Gene length is variable and ranges from few kilobases (1 kilobase equal to 1000 base pairs) to millions of base pairs. Interestingly, introns rather than exons constitute greater part of gene length. The exact site or position of a particular gene on a chromosome is called locus while a variant form of a gene is called allele. A gene is usually represented by two alleles. If both alleles are similar the individual is homozygous for this gene. On the other hand, presence of two different alleles of a gene renders an individual heterozygous for such gene.

Base Gentica Fertilidade Masculina

Hamada, Esteves, Agarwal: Genetics and Male Infertility. In: Dubey A [ed]. Infertility: Management and Treatment, Jaypee Med. Pub., In pressIt has been estimated that 2,000 genes are essential for spermatogenesis, from which only 30 genes are present in Y chromosome and most of the remaining genes are on the autosomal chromosomes. Base Gentica Fertilidade MasculinaAdaptado de: Esteves & Agarwal. Novel concepts in male infertility. Int Braz J Urol 2011;37:5-15.

Genotype is the actual genetic code that controls physical and performance traits. The genotype of an individual cannot be changed by environmental factors. Phenotype is the discernible characteristic or trait of an individual such as specific external feature, biochemical or physiological properties or behavior. Phenotype is the result of the expression of the genotype. However, environmental factors may play a role in alteration of genotype-phenotype correlation.

Gentipo Cls. Somticas AnormalHipogonadismo Hipogonadotrfico: ex.: S. KallmanAberrao Cromossmica (aneuploidias/translocaes): ex. S. KlinefelterMutaes Gnicas: ex. gene CFTR (CBAVD)Deleo Cromossmica Parcial: ex. Microdeleo Y Alts. Gnicas c/Repercusso Funcional: ex. S. KartagenerGentipo Cls. Somticas Normal Anormalidades cromossmicas nos espermatozidesAlterao integridade DNA espermtico Defeitos mitocondriaisAlteraes epigenticas (ex. S. Angelman, Beckwith-Wiedemann)Infertilidade Causa GenticaHamada, Esteves, Agarwal: Genetics and Male Infertility. In: Dubey A [ed]. Infertility: Management and Treatment, Jaypee Med. Pub., In pressInfertilidade Causa GenticaAberraes Cromossmicas & Concentrao Espermtica

Chandley et al. , 1972; De Kretser et al, 1972; Matsuda et al, 1992Esteves, 8Nos homens infrteis, a incidncia de alteraes cromossmicas de cerca de 6%, mas aumenta medida que diminui a concentrao espermtica. Nos indivduos azoosprmicos, a incidncia destas alteraes ultrapassa 10%. 1. Aberraes CromossmicasSndrome KlinefelterPrevalncia:1:600-1.000 nascidos sexo masculino~5% casos oligozoospermia grave~11% casos azoospermia no-obstrutivaCaritipo (Aneuploidia): Clssico: 47,XXY; Mosaico: 47,XXY/46,XYClnica:Testculos hipotrficosFSH elevado, hipogonadismo, ginecomastia (1/3 casos)Azoospermia (92% casos)Oligozoospermia grave (~0.1 milho/mL)

Esteves, 9Dentre as aberraes cromossmicas, a sndrome de Klinefelter (47,XXY) a mais comum, e geralmente associa-se hipotrofia ou atrofia testicular, nveis elevados do FSH srico e azoospermia, embora graus variveis de acometimento da espermatognese ocorram nos indivduos com caritipo em mosaico (46,XY/47,XXY). 1. Aberraes Cromossmicas Sndrome KlinefelterAzoospermia: Focos clulas germinativas: 40-50% casosHistologia: SCO (espermatognese focal 8-24% tbulos)Importncia: captao Sptz para ICSI Espermatognia 47,XXY:Gametas aneuplides e haplidesImpacto:Chance paternidade biolgica via ICSIRisco Gentico:- Abortamento- Sade prole (Klinefelter, Turner)- Diagnstico gentico pr-implantacional (PGD)

Esteves, 10Sciurano et al., Hum Reprod. 2009

2. Mutaes Gnicas Agenesia Congnita Canais DeferentesPrevalncia:Homens infrteis: 1,3%; Azoospermia Obstrutiva: 6%Caracterstica: Mutao gene fibrose cstica (7q:190kb e 27 exons)CFTR: cystic fibrosis transmembrane conductance regulatorClnica:Azoospermia + Hipospermia (pH cido)FSH normalEpiddimos engurgitados (ausncia parcial)Deferentes ausentesVesculas seminais hipoplsicas ou ausentes

Esteves, 11

Both seminal vesicles and vas deferens have a common embryologic origin. As such, when congenital bilateral absence of vas deferens (CBAVD) is diagnosed it is often associated with seminal vesicles hypoplasia/ agenesia. This is an important aspect on the differential diagnosis of azoospermia. In CBAVD, no fructose can be found in the seminal fluid and volume is lower.

Dentre as mutaes gnicas, a mais freqente est relacionada ao gene da fibrose cstica (gene CFTR), localizado no brao longo do cromossomo 7. Dependendo da extenso da mutao, pode ocorrer fibrose cstica (doena autossmica recessiva potencialmente letal), ou a sua forma leve, que se manifesta pela agenesia congnita bilateral dos vasos deferentes, e acomete cerca de 1,3% dos homens infrteis. Mutaes no gene CFTR comprometem o desenvolvimento das estruturas derivados dos ductos de Wolff (ductos eferentes, epiddimos e canais deferentes), podendo ainda associar-se hipoplasia ou agenesia das vesculas seminais e agenesia renal unilateral. Aproximadamente 80% dos homens com ausncia dos deferentes possuem mutaes no gene CFTR2. Mutaes Gnicas Agenesia Congnita Canais DeferentesMutao gene CFTR detectada 80% CBAVDF508, polimorfismos 5T/7T, R117H (+1,500 mutaes)Agenesia unilateral canal deferente pode estar associada mutao CFTR; agenesia renal ipsilateral pode coexistirObstruo idioptica e S. Young (sinusite crnica, bronquiectasia e azoospermia obstrutiva) pode estar associada mutao CFTR

Esteves, Miyaoka & Agarwal. An update on the initial assessment of the infertile male. CLINICS 2011; 66:1-10. Esteves, 12Approximately 80% of men presenting with CBVAD have a CFTR mutation. As the diagnostic methods routinely used are not 100% sensitive, a man with CBAVD should be assumed to harbor a CFTR mutation. Testing should be offered to his female partner to exclude the possibility that she may also be a carrier (approximately 4% risk) before using his sperm for assisted conception.

The common CFTR mutations are i) F508 (missing three nucleotides that encode the phenylalanine at position 508 in the protein's amino acid sequence) represent 6070% of the CF mutations in carriers and patients, ii) polymorphisms reducing the production of the CFTR protein (5T, 7T) have been shown within intron 8, which results in a reduction of the splicing efficiency of the CFTR gene, and iii) the missense R117H mutation in exon 4 is also related to CBAVD in association with the 5T variant.

Esteves SC et al. Success of percutaneous sperm retrieval and intracytoplasmic sperm injection (ICSI) in obstructive azoospermic (OA) men according to the cause of obstruction. Fertil Steril. 2010;94 (Suppl):S233.Esteves, 132. Mutaes Gnicas Agenesia Congnita Canais Deferentes

2. Mutaes Gnicas Agenesia Congnita Canais DeferentesCBAVD:- Espermatognese preservada- Aspirao espermatozides & ICSI Risco Gentico :Mulheres caucasianas tem 4% chance de serem portadoras mutaes gene CFTR - Risco fibrose cstica prole: 25% chanceFC: doena autossmica recessiva letalDiagnstico gentico pr-implantacional (PGD)

Esteves, 14Esteves, Miyaoka & Agarwal. An update on the initial assessment of the infertile male. CLINICS 2011; 66:1-10. Yp: regio SRY associada ao desenvolvimento testicularYq: AZF associada espermatognese 3. Deleo Gnica Microdelees Cromossomo Y

Hamada, Esteves, Agarwal: Genetics and Male Infertility. In: Dubey A. In press3. Deleo Gnica Microdelees Cromossomo YPrevalncia:1:2.000-3.000 meninos nascidosHomens infrteis: 5-12%Caracterstica: Delees do tipo de novoClnica:Testculos normais ou hipotrficosFSH normal ou elevadoAzoospermia ou Oligozoospermia gravePode coexistir com varicocele e/ou criptorquidia

Esteves, 16

Esteves, Miyaoka & Agarwal. An update on the initial assessment of the infertile male. CLINICS 2011; 66:1-10. Dentre as aberraes cromossmicas, a sndrome de Klinefelter (47,XXY) a mais comum, e geralmente associa-se hipotrofia ou atrofia te