The genetics of human reproduction

Male Infertility in Robertsonian Translocation: A Case Report

Case series

Patients: Male, 34-year-old • Male, 35-year-old

Final Diagnosis: Primary infertility • Robertsonian translocation

Symptoms: Asymptomatic

Medication: —

Clinical Procedure: —

Specialty: Urology

Reproductive biotechnology and "big" biological questions

In recent decades, scientists have learned to manipulate that cardinal characteristic of life, reproduction, with powerful techniques like artificial insemination, contraception, embryo transfer, cryopreservation, and cloning by nuclear transfer. While these technologies often are used for practical applications and basic research, they have another profound intrinsic quality, which is to engender deep-seated thinking about important biological questions. Examples that stimulate such thinking include a goat's giving birth to her identical twin sister via splitting embryos, cryopreservation, and embryo transfer; that a parthenogenetic embryo can never become an animal but can become a genetic mother via an aggregation chimera; or that a somatic cell can become the sole genetic parent of a calf via cloning. In this paper, I illustrate this thought-stimulating quality by considering contributions of reproductive technologies to understanding, if not completely answering, several important biological questions.

Genetics of idiopathic male infertility: Y chromosomal azoospermia factors (AZFa, AZFb, AZFc)

Y chromosomal spermatogenesis loci in Yq11 are disrupted with a frequency of 5-20% in men suffering from idiopathic infertility (azoospermia or severe oligozoospermia). They were designated azoospermia factors (AZFa, AZFb, AZFc). An efficient schedule for their molecular diagnosis in each infertility clinic is presented. In addition, I will include our current knowledge about their biological function during human germ cell development and a description of their pathology in men suffering from deletion of one or more AZF loci. Each Y gene expressed in testis tissue and located in Yq11, in a position overlapping one of the AZF loci, is an AZF candidate gene. Their diagnostic analysis will be described in a separate section. The clinical diagnosis of AZF candidate genes cannot substitute for diagnosis of the genetically defined AZF loci. Therefore, analysis of candidate genes is aimed at answering the question of whether mutations in their exon structures are able to induce the same pathological phenotypes as deletion of the corresponding AZF locus. Only after these gene mutations have been analysed can the AZF candidate gene be designated as a real AZF gene. Therefore, the basic aim of our current research is isolation and identification of all AZF genes.

The incidence of aneuploidy after single pulse electroactivation of mouse oocytes

A brief electric pulse often produces a high rate of activation of recently ovulated oocytes. Some other efficient parthenogenetic stimuli, such as alcohol, however, disrupt the spindle apparatus and increase the incidence of aneuploidy. In this paper, we have determined whether electroactivation per se increases the incidence of chromosomal segregation errors in haploid parthenogenones as evidenced at first cleavage mitosis. Superovulated F1 hybrid female mice were killed at 15.5, 18.5, 22.5, and 25 h after the HCG injection. Batches of 10-12 cumulus-denuded oocytes were transferred to an electroactivation chamber containing mannitol which was connected to a high voltage pulse stimulator and the pulse was triggered once. A high proportion of oocytes activated following this treatment, but only the single-pronuclear haploid parthenogenones were incubated overnight in medium containing colcemid, to determine the incidence of aneuploidy as evidenced at first cleavage mitosis. "Sham" electroactivation groups were also examined for evidence of activation and aneuploidy as described above. In these cases, cumulus-denuded oocytes were put through the electroactivation chamber but the pulse was not triggered. A further group of oocytes was studied to determine the effect of handling and exposure to hyaluronidase on activation frequency and parthenogenetic pathways. Finally, the spontaneous rate of aneuploidy was examined in fertilised embryos of F1 hybrid female mice x Rb(1.3)1Bnr male mice at first cleavage mitosis. The results show that single pulse electroactivation does not increase the level of aneuploidy in single-pronuclear parthenogenous compared to the "sham" group or the spontaneous rate observed in 1-cell fertilised embryos, nor does aneuploidy appear to increase with postovulatory age.(ABSTRACT TRUNCATED AT 250 WORDS)