Hypertriglyceridemia is associated with increased insulin resistance in subjects with normal glucose tolerance: evaluation in a large cohort of subjects assessed with the 1999 World Health Organization criteria for the classification of diabetes

The current study retrospectively examined the association between insulin resistance and plasma triglycerides (TG) in a group of subjects with normal glucose tolerance. Among 1,434 subjects consecutively undergoing a standard oral glucose tolerance test (OGTT) between 1993 and 1998, 567 (age, 15 to 78 years) were classified as having a normal glucose tolerance according to the 1999 World Health Organization (WHO) criteria and were selected for the study. Serum insulin was measured by radioimmunoassay (INSI-CTK, Dia Sorin, Saluggia, Italy). Intra-assay and interassay coefficients of variation for the method were less than 4% and less than 8.5%, respectively. Insulin resistance was calculated by a homeostasis model assessment (HOMA(IR) = fasting serum insulin [mU/mL] x fasting blood glucose [mmol/L]/22.5). A very significant correlation was found between HOMA(IR) and plasma TG (r = 0.27, P < 1.02E(-10)). Multiple regression analyses confirmed plasma TG as independent variables explicative of HOMA(IR). When subjects were evaluated according to tertiles of TG, those in the upper two tertiles were older (P <.001) and presented higher body mass index (BMI) values (P <.0001) in comparison to subjects in the lower tertile. A positive trend (analysis of variance [ANOVA]) was found in regard to systolic (P <.05) and diastolic blood pressure (P <.0001), fasting blood glucose (P <.01), fasting serum insulin (P <.0001), and total cholesterol (P <.0001), while a negative trend was found in regard to high-density lipoprotein cholesterol (HDL-C) (P <.0001). Insulin resistance, calculated as HOMA(IR), was higher in the upper two tertiles of TG in comparison to the lower tertile (P <.001 and P <.0001, respectively), with a statistically significant trend for the entire group (first tertile, 1.85 +/- 0.94; second tertile, 2.28 +/- 1.10; third tertile, 2.65 +/- 1.71; ANOVA: P <.0001). In conclusion, this study shows an association between high levels of circulating TG and insulin resistance in patients with normal glucose tolerance seen in an atherosclerosis prevention clinic. This association is also present at levels of plasma TG considered to be normal and is associated with a cluster of cardiovascular risk factors.

Defect formation in the Swift-Hohenberg equation

We study numerically and analytically the dynamics of defect formation during a finite-time quench of the two-dimensional Swift-Hohenberg (SH) model of Rayleigh-Bénard convection. We find that the Kibble-Zurek picture of defect formation can be applied to describe the density of defects produced during the quench. Our study reveals the relevance of two factors: the effect of local variations of the striped patterns within defect-free domains and the presence of both pointlike and extended defects. Taking into account these two aspects we are able to identify the characteristic length scale selected during the quench and to relate it to the density of defects. We discuss possible consequences of our study for the analysis of the coarsening process of the SH model.

The human Y chromosome's azoospermia factor b (AZFb) region: sequence, structure, and deletion analysis in infertile men

Microdeletions of the Y chromosome long arm are the most common mutations in infertile males, where they involve one or more "azoospermia factors" (AZFa, b, and c). Understanding of the AZF structure and gene content and mapping of the deletion breakpoints in infertile men are still incomplete. We have assembled a complete 4.3 Mb map of AZFb and surrounding regions by means of 38 BAC clones. The proximal part of AZFb consists of large repeated sequences organised in palindromes, but most of it is single copy sequence. A number of known and novel genes and gene families map in this interval, and most of them are testis specific or have testis specific transcripts. STS mapping allowed us to identify four severely infertile subjects with a deletion in AZFb with similar breakpoints, therefore suggesting a common deletion mechanism. This deletion includes at least five single copy genes and two duplicated genes, but does not remove the historical AZFb candidate gene RBMY1. These data suggest that other genes in AZFb may have important roles in spermatogenesis. We had no evidence for homologous recombination between large repeats as a possible deletion mechanism, as shown for AZFa and AZFc. However, identical sequences in AZFb and AZFc exist, and this finding could explain deletions found in these regions.

Bilateral subthalamic nucleus stimulation improves health-related quality of life in PD

In order to assess the impact of bilateral subthalamic nucleus (STN) stimulation in PD on quality of life, the PD Quality of Life questionnaire was assessed in 60 consecutive patients with PD before surgery and 12 months after surgery. All aspects of quality of life, including motor (+48%), systemic (+34%), emotional (+29%), and social (+63%) dimensions, significantly improved with long-term STN stimulation.

The impact on Parkinson's disease of electrical parameter settings in STN stimulation

BACKGROUND

The main advantage of deep brain stimulation (DBS) in the treatment of PD is that the electrical settings can be adjusted to optimize benefits and minimize adverse effects. The main objective of this study was to discover how varying these electrical parameters impacted on parkinsonian motor signs.

METHODS

Twelve patients with PD with chronic bilateral subthalamic nucleus (STN) stimulation were selected. The authors evaluated the effects of a variation in the voltages, frequencies, and pulse widths on tremor, bradykinesia, and rigidity using two different paradigms: one in which the total electrical energy delivered was held constant, and one in which this was varied. Up to 26 parameter conditions were tested under double blind randomized conditions.

RESULTS

Voltages >or=3 V and frequencies >or=130 Hz led to the greatest improvement in all three parkinsonian signs. A rate of 5 Hz significantly worsened akinesia. The combination of the highest voltage with the narrowest pulse width was most effective.

CONCLUSIONS

This study confirms that the most beneficial effects induced by STN stimulation are obtained at high frequencies and that voltage is the most critical factor to obtain adequate alteration in STN activity. The mechanisms by which STN DBS improves parkinsonism remain speculative.

Microscopic model for thin film spreading

A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuations of the precursor film observed in spreading experiments. Matter is transported both by holes and particles, and the distribution of each can be described by driven diffusion with a moving boundary. This picture leads to a stochastic partial differential equation for the shape of the boundary. Explicit analytic results are obtained which agree with the simulations of the lattice gas.

Dynamic renormalization group study of a generalized continuum model of crystalline surfaces

We apply the Nozières-Gallet dynamic renormalization group (RG) scheme to a continuum equilibrium model of a d-dimensional surface relaxing by linear surface tension and linear surface diffusion, and which is subject to a lattice potential favoring discrete values of the height variable. The model thus interpolates between the overdamped sine-Gordon model and a related continuum model of crystalline tensionless surfaces. The RG flow predicts the existence of an equilibrium roughening transition only for d=2 dimensional surfaces, between a flat low-temperature phase and a rough high-temperature phase in the Edwards-Wilkinson (EW) universality class. The surface is always in the flat phase for any other substrate dimensions d>2. For any value of d, the linear surface diffusion mechanism is an irrelevant perturbation of the linear surface tension mechanism, but may induce long crossovers within which the scaling properties of the linear molecular-beam epitaxy equation are observed, thus increasing the value of the sine-Gordon roughening temperature. This phenomenon originates in the nonlinear lattice potential, and is seen to occur even in the absence of a bare surface tension term. An important consequence of this is that a crystalline tensionless surface is asymptotically described at high temperatures by the EW universality class.

A novel approach for the analysis of DAZ gene copy number in severely idiopathic infertile men

The deleted-in-azoospermia (DAZ) gene family constitutes the major candidate for the AZFc (azoospermia factor c) phenotype of male infertility, being deleted in about 10% of azoospermic and severely oligozoospermic subjects. Four DAZ genes are arranged in two clusters in AZFc, and standard analysis by PCR cannot distinguish among the different copies. Therefore only deletions of the entire gene cluster can be identified. We developed a PCR amplification-restriction digestion assay able to distinguish from DAZ genes for single nucleotide variants. Then we applied this approach to screen a group of idiopathic infertile men in which the DAZ genes presence was previously assessed by standard PCR analysis. Two patients out of 25 showed deletion of two copies of DAZ (DAZI and 2), suggesting that this mutation was actually the cause of spermatogenic damage. This preliminary screening demonstrates that deletions of copies of DAZ genes may be often found in severely infertile men and it strengthens the role of this gene family in spermatogenesis. Furthermore, this simple method, being able to distinguish among the different DAZ copies, could be used to screen a larger number of patients and to perform a more accurate diagnosis.

Internal fluctuations effects on Fisher waves

We study the diffusion-limited reaction A+A<-->A in various spatial dimensions to observe the effect of internal fluctuations on the interface between stable and unstable phases. We find that, similar to what has been observed in d = 1 dimensions, internal fluctuations modify the mean-field predictions for this process, which is given by Fisher's reaction-diffusion equation. In d>1 the front displays local fluctuations perpendicular to the direction of motion which, with a proper definition of the interface, can be fully described within the Kardar-Parisi-Zhang (KPZ) universality class. This clarifies the apparent discrepancies with KPZ predictions reported recently.

Intestinal motor stimulation by the 5-HT4 receptor agonist ML10302: differential involvement of tachykininergic pathways in the canine small bowel and colon

5-Hydroxytryptamine (5-HT)4 receptor agonists stimulate gut motility through cholinergic pathways, although there are data suggesting that noncholinergic (tachykininergic) excitatory pathways may also be involved. Differences may exist between the small bowel and colon. Our aims were: (i) to compare the prokinetic effect exerted by the 5-HT4 receptor agonist ML10302 in the canine small bowel and colon in vivo; and (ii) to investigate the role of tachykininergic pathways in mediating this response. In fasting, conscious dogs, chronically fitted with electrodes and strain-gauge force transducers along the small bowel and colon, intravenous injection of ML10302 (35 microg kg-1) immediately stimulated spike activity and significantly increased propagated myoelectrical events at both intestinal levels. In the small bowel, the effects of ML10302 were unchanged by previous administration of the selective NK1 tachykinin receptor antagonist SR140333, the NK2 tachykinin receptor antagonist SR48968, or the NK3 tachykinin receptor antagonist SR142801. In the colon, all tachykinin receptor antagonists significantly inhibited stimulation of spike and mechanical activity by ML10302, without affecting ML10302-induced propagated myoelectrical events. Atropine (100 microg kg-1 i.v.) suppressed the stimulatory effect of ML10302 at both intestinal levels. In conclusion, the 5-HT4 receptor agonist ML10302 induced significant prokinesia both in the small bowel and colon through activation of cholinergic pathways. Tachykininergic pathways are not involved in the ML10302-induced prokinesia in the small bowel, but they play an important role in mediating the colonic motor response to ML10302.

Prognostic value of Y deletion analysis. The role of current methods

Y chromosome microdeletions represent the most frequent genetic alteration in azoospermic and severely oligozoospermic men, and screening for microdeletions in AZFa, b and c are routinely performed in the major andrology and infertility centres. Since patients with Y microdeletions often require intracytoplasmic sperm injection (ICSI), the question of whether the type of the microdeletion present could have prognostic value for the presence of spermatozoa in the ejaculate or in the testes [by testicular sperm extraction (TESE)] is an interesting one. The review of the literature on this topic showed that there is still no clear genotype--phenotype relationship, i.e. similar testicular alterations may be caused by different types of microdeletions, and apparently identical microdeletions may be associated with diverse tubular damage. Even in azoospermic men, the localization of the microdeletion cannot be used as a valid prognostic parameter before TESE--ICSI to identify patients with spermatozoa in their testes. The only finding with absolute negative prognostic value is the presence of complete AZFa--c deletions, which are invariably associated with an absence of spermatozoa. Microdeletions in AZFa or AZFb seem to have promising prognostic value, but more data and gene-specific deletions have to be provided to draw clear conclusions. The absence of a clear genotype--phenotype relationship, and therefore of a prognostic value of Y deletion analysis, is probably due to the current methods used for the screening of the microdeletions. In fact, to date most centres do not use gene-specific markers but instead use anonymous primers that contribute little information to the pathogenic role of the microdeletions.

Deep brain stimulation in the treatment of severe dystonia

A retrospective study of a consecutive series of 19 patients with medically intractable dystonia treated with uni- or bilateral deep brain stimulation (DBS) is reported. A minimal follow-up of 6 months was available, up to eleven years in one patient. The first twelve consecutive patients (4 with primary and 8 with secondary dystonia) were treated with chronic stimulation of the posterior part of the ventrolateral thalamic nucleus (VLp). In this group global functional outcome was improved in 8 patients, although dystonia movement and disability scale scores did not show significant improvement. Of the 12 patients treated first by VLp DBS, three (1 primary and 2 secondary dystonia) underwent pallidal (GPi) DBS after the VLp DBS failed to improve their symptoms. The last seven consecutive patients (5 primary and 2 secondary dystonia) were treated directly with GPi DBS. Extracranial infection prevented chronic GPi DBS in one patient. In another GPi patient, preliminary negative tests with the electrodes discouraged implantation of the stimulators, and the patient was not treated with chronic DBS. In the remaining group of eight patients including those previously treated with VLp DBS, chronic GPi DBS resulted in a significant improvement in the dystonia movement scale and disability scores. Although this is a retrospective study dealing with dystonia of heterogeneous etiology, the results strongly suggest that GPi DBS has a better outcome than VLp DBS.

Sertoli cell function in infertile patients with and without microdeletions of the azoospermia factors on the Y chromosome long arm

Deletions of the azoospermia factors on the Y chromosome long arm are an important cause of male infertility, and they may involve germ cell-specific genes or ubiquitously expressed genes. To date, no clinical or hormonal parameters have yet been found to distinguish patients with and without Yq microdeletions. In particular, Sertoli cell function, as evaluated by inhibin B, has not yet been described. Our hypothesis was that microdeletions involving genes specifically expressed in germ cells should not alter Sertoli cell function. To do this, we have evaluated the testicular hormonal function in infertile patients affected by severe testiculopathies with and without Yq microdeletions, with particular emphasis on Sertoli cell function. We studied 102 well-characterized infertile patients; 27 had Yq microdeletions, and 75 were classified as idiopathic infertiles. Patients with Yq microdeletions had lower FSH and higher inhibin B plasma concentrations with respect to patients without microdeletions, suggesting that Sertoli cell function in Yq-deleted men is only partially altered. Furthermore, patients with deletions involving germ cell-specific genes had higher concentrations of inhibin B with respect to patients with deletions of ubiquitously expressed genes. These results suggested that a specific alteration of germ cells only partially influences Sertoli cell function. Hormonal status of patients without deletions suggested that in such cases the cause that has determined the spermatogenic defect may have damaged both Sertoli and germ cells. Inhibin B production in patients with Yq deletions was about 70% higher than the nondeleted patients, and the functional relationship between FSH and inhibin B was normally preserved. This study elucidated the multifactorial mechanisms underlying spermatogenic defects, where Sertoli cells may be normally functioning or damaged depending on the primary cause that has determined the testicular damage.

Evidence for FSH-dependent upregulation of SPATA2 (spermatogenesis-associated protein 2)

Here we report the cloning and characterization of a novel cDNA named spata 2. SPATA2 is the ortholog of PD1, a human testicular protein which has been suggested to play a role in spermatogenesis. The spata 2 sequence reveals an open reading frame encoding a protein of 511 amino acids. Northern blot analysis with rat mRNA demonstrated two distinct transcripts of 2.2 and 4.0 kb. Tagging recombinant SPATA2 with the green fluorescent protein (GFP) and expressing the chimeric polypeptide in HLtat transfected cells indicated that SPATA2 is located in the nucleus. RT-PCR analysis revealed that spata 2 mRNA is expressed in the testis and to a lesser extent in the brain while skeletal muscle and kidney showed a barely visible signal. The same analysis demonstrated that isolated Sertoli cells express spata 2 mRNA. Treating Sertoli cells with FSH in vitro induced remarkable changes in the steady-state level of spata 2 mRNA in a time-dependent manner. In developing testis spata 2 transcripts were first detected 10 days post partum and expression levels increased steadily with age. The ability of FSH to stimulate spata 2 mRNA expression as well as its developmental expression suggests that this protein might play a role in regulating spermatogenesis and thus, according to the Gene Nomenclature Committee, we propose the name SPATA2 (Spermatogenesis associated protein 2) for this protein (or gene).

[Microdeletion of chromosome Y in male infertility: role of the DAZ gene]

Microdeletions of the Y chromosome represent the most frequent cause of male infertility, being responsible for 10-15% of cases of azoospermia or severe oligozoospermia. Such mutations localize in one or more loci named azoospermia factor (AZF) a, b and c. Mutations more frequently involve the DAZ gene in AZFc, and could determine both azoospermia and severe oligozoospermia. It is therefore difficult to find a clear relationship between genotype and phenotype. DAZ is present in multiple copies in AZFc, and this causes the gene to be difficult to analyze. In fact, polymerase chain reaction, the principal technique utilized for detection of the deletions, cannot distinguish among the different copies of the gene. Furthermore, it is not clear if all the DAZ copies are expressed in the testis, and other genes, such as CDY1, map in AZFc; therefore their alteration may play a role in determining the phenotype. In this review we report the current knowledge on the function of the Y chromosome in human spermatogenesis. In particular we analyze some of our experimental studies on the role of the DAZ gene family. Expression studies allowed us to clarify that an altered expression of DAZ might cause infertility in patients with severe testiculopathies. Furthermore, we describe for the first time a deletion not involving all the DAZ copies in a patient with severe hypospermatogenesis and we clarify that CDY1 is not involved in the testicular damage observed in patients with deletions of DAZ. These studies elucidate the role of DAZ and have important clinical consequences in the diagnostic and therapeutic approach of the infertile patient, above all when he is a candidate for assisted reproduction techniques, due to the possibility of transmitting the genetic alteration to the offspring.

Y chromosome microdeletions and alterations of spermatogenesis

Three different spermatogenesis loci have been mapped on the Y chromosome and named "azoospermia factors" (AZFa, b, and c). Deletions in these regions remove one or more of the candidate genes (DAZ, RBMY, USP9Y, and DBY) and cause severe testiculopathy leading to male infertility. We have reviewed the literature and the most recent advances in Y chromosome mapping, focusing our attention on the correlation between Y chromosome microdeletions and alterations of spermatogenesis. More than 4,800 infertile patients were screened for Y microdeletions and published. Such deletions determine azoospermia more frequently than severe oligozoospermia and involve especially the AZFc region including the DAZ gene family. Overall, the prevalence of Y chromosome microdeletions is 4% in oligozoospermic patients, 14% in idiopathic severely oligozoospermic men, 11% in azoospermic men, and 18% in idiopathic azoospermic subjects. Patient selection criteria appear to substantially influence the prevalence of microdeletions. No clear correlation exists between the size and localization of the deletions and the testicular phenotype. However, it is clear that larger deletions are associated with the most severe testicular damage. Patients with Y chromosome deletions frequently have sperm either in the ejaculate or within the testis and are therefore suitable candidates for assisted reproduction techniques. This possibility raises a number of medical and ethical concerns, since the use of spermatozoa carrying Y chromosome deletions may produce pregnancies, but in such cases the genetic anomaly will invariably be passed on to male offspring.

Different insulin-like 3 (INSL3) gene mutations not associated with human cryptorchidism

Cryptorchidism is the most frequent congenital anomaly of the urogenital tract in the male, but its etiology is for the most part unknown. Evidence suggests that a possible genetic cause may be involved. Animal models support this hypothesis, and in particular INSL3 (Leydig insulin-like 3 hormone) has been proposed as putative gene for cryptorchidism, since male mice mutant for Insl3 exhibit bilateral abdominal cryptorchidism due to alteration of gubernaculum development. In this study, we analyzed whether mutations in INSL3 could be associated with human cryptorchidism. Heteroduplex analysis and sequencing of both exons of INSL3 in 65 ex-cryptorchid patients and a group of control subjects allowed us to find four nucleotide changes in the sequence of exon I. These mutations are all single base substitutions from G to A at position 27, 96, 126 and 178. Only the 178G-->A substitution changes codon 60 from alanine to threonine (A60T). All mutations were found in comparable distribution in ex-cryptorchid patients and non-cryptorchid men. Therefore, all mutations represent neutral polymorphisms not associated with phenotype. This study confirms previous observations and demonstrates a novel polymorphism in the INSL3 gene. In contrast to that described for the mutant mouse, these data indicate that mutations of INSL3 do not seem to represent a frequent cause of cryptorchidism.

Variational mean-field study of a continuum model of crystalline tensionless surfaces

We study analytically the equilibrium and near-equilibrium properties of a model of a d-dimensional surface relaxing via linear surface diffusion and subject to a lattice potential. We employ the variational mean-field formalism introduced by Saito for the study of the sine-Gordon model. In equilibrium, our variational theory predicts a first-order roughening transition between a flat low-temperature phase and a rough high-temperature phase with the properties of the linear molecular-beam epitaxy equation. Moreover, the study of a Gaussian approximation to the Langevin dynamics of the system indicates that the surface shows hysteresis when temperature is continuously tuned. Out of equilibrium, these approximate Langevin dynamics show that the surface mobility can have different behaviors as a function of a driving flux. Some considerations are made regarding different underlying lattices, and connections are drawn to related models or different approaches to the same model we study.

Gastric motor effects of triptans: open questions and future perspectives

Sumatriptan is a 5-HT1B/D receptor agonist of documented efficacy in relieving migraine and associated symptoms such as nausea and vomiting. In the past decade, several studies reported an important delay of gastric emptying induced by sumatriptan in healthy humans. The impact of this gastric motor effect of sumatriptan in migraineurs is difficult to predict: a further delay in gastric emptying could be detrimental (i.e. increased nausea and epigastric symptoms) in patients already having delayed gastric emptying. However, in patients with functional dyspepsia, sumatriptan is also reported to improve gastric accommodation to a meal and reduce perception of gastric distention, hence relieving epigastric symptoms. Thus, reduced visceral perception could be a mechanism involved in reducing nausea during a migraine attack. Paradoxically, sumatriptan is reported both to relieve the nausea of a migraine attack and to have nausea as a side effect. Although careful analysis of the time of onset of nausea may offer a clue as to the origin of this symptom, available data do not support definite conclusions, all the more so because the gastric motor effect of second-generation triptans are still unexplored. Taken together, the available evidence warrants further studies to clarify the following issues: first, the mechanism responsible for the gastric motor effect of sumatriptan [receptor subtype(s) involved; central vs peripheral mechanism]; secondly, the effects on gastric motility/visceral sensitivity of second-generation triptans (which are 5-HT1B/D receptor agonists) and more recent selective 5-HT1D receptor agonists (proposed as investigational antimigraine agents with less potential to induce coronary vasoconstriction through 5-HT1B receptors); finally, the possible use of drugs improving gastric accommodation to a meal in the management of those dyspeptic patients with impaired fundic relaxation/altered visceral sensitivity.

Targeting the basal ganglia for deep brain stimulation in Parkinson's disease

The revitalization of surgery for Parkinson's disease (PD) has fueled discussion about the best methodology to define the target. Placement of electrodes for deep brain stimulation (DBS) requires the usual stereotactic technique but the argument is mainly centered on whether or not microrecording neuronal activity is necessary. We compared the accuracy of calculating the coordinates X (medio-lateral) and Y (rostro-caudal) considered by the classic stereotactic method, i.e., definition of the AC-PC intercomissural line by MRI and a digitized version of the Schaltenbrand's atlas, with final electrode placement according with microrecording and microstimulation in 21 patients. For both the globus pallidum internum (GPi) (n = 21) and the subthalamic nucleus (STN) (n = 36) there was, respectively, a 43% and 45% mismatching of more than 3 mm between the theoretic coordinates and the final site of electrode location. This applies to both the X and Y planes. Accuracy was not improved in patients (n = 11) in whom the bilateral procedure was undertaken in a single day. We conclude that proper electrode positioning of the STN and GPi requires fine electrophysiologic assessment.

CDY1 analysis in infertile patients with DAZ deletions

The DAZ (deleted in azoospermia) gene family is considered the major AZFc ("azoospermia factor" c) candidate responsible for male infertility. However, other genes have been recently mapped to this region and they could contribute to the AZFc phenotype. In particular, the testis-specific CDY1 (chromadomain protein 1) gene has one copy within the DAZ cluster and another one at its distal end. Therefore, this gene could be associated with the spermatogenic damage observed in DAZ-deleted patients since at least one CDY1 copy is invariably absent in these patients. In this study, we investigated whether selected infertile patients affected by different testiculopathies caused by DAZ deletions retained CDY1 and if a genotype-phenotype relation could be demonstrated. We found 3 out of 17 patients with absence of both CDY1 copies, while 14 patients have only one CDY1 copy absent. Two out of the 3 patients with deletion of both copies of CDY1 were affected by severe hypospermatogenesis while one patient presented Sertoli cell-only syndrome. Therefore, there was no clear relation between genotype and phenotype, and the loss of the distal copy of CDY1 does not seem to worsen the phenotype of infertile patients with deletion of the DAZ gene cluster. However, a possible contribution of CDY1 in determining the spermatogenic alteration could not be excluded.

Role of the AZFa candidate genes in male infertility

The AZFa region on the Y-chromosome long arm has been recently assembled in a complete sequence map contained in a contig and shown to span more than 1 Mb. It contains three genes, USP9Y, DBY and UTY, but only the former two can be at present considered candidate genes for the infertile phenotype associated with deletion of this interval. These genes have X-homologues and are expressed in many tissues, even if DBY has a shorter transcript expressed in the testis only, strengthening its role in spermatogenesis. Only few patients with gene-specific deletion have been reported and a clear genotype-phenotype relation is still lacking. While deletions or even smaller mutations in USP9Y seem to be associated with a testicular phenotype of severe hypospermatogenesis, patients with deletions of DBY may present both Sertoli cell-only syndrome and severe hypospermatogenesis. On the contrary, the phenotype of patients with deletion of both USP9Y and DBY seem to be invariably azoospermia with a testicular histology of Sertoli cell-only.

Y-chromosomal DNA haplotypes in infertile European males carrying Y-microdeletions

We have determined Y-chromosomal DNA haplotypes in 73 infertile European males carrying Y microdeletions and compared them with the haplotypes of 299 infertile males lacking microdeletions. Chromosomes were typed with a set of 11 binary Y markers, which identified 8 haplogroups in the sample. Haplogroup frequencies were compared between 3 microdeletion classes and the non-deleted infertile males. Deletions arise on many different haplotypic backgrounds. No statistically significant differences in frequency were seen, although the small number of AZFa deletions lay predominantly on one branch of the Y haplotype tree.

Male infertility caused by a de novo partial deletion of the DAZ cluster on the Y chromosome

Deletions in distal Yq interval 6 represent the cause of 10-15% of idiopathic severe male infertility and map to a region defined AZFc (azoospermia factor c). The testis-specific gene DAZ is considered a major AZFc candidate, and its deletion has been associated with a severe disruption in spermatogenesis. However, DAZ is actually a multicopy gene family consisting of seven clustered copies spanning about 1 megabase. Only deletions removing the entire DAZ gene cluster together with other genes have been reported in infertile males. Because no case of spermatogenic failure has been traced to intragenic deletions, point mutations, or even deletions not involving all the DAZ copies, the definitive proof for a requirement of DAZ for spermatogenesis is still debatable. Here we report the first case of a partial deletion of the DAZ cluster removing all but one of the copies. This deletion is present in a patient affected with severe oligozoospermia who had a testicular phenotype characterized by a great quantitative reduction of germ cells (severe hypospermatogenesis). The absence of this deletion in the fertile brother of the patient suggests that this de novo mutation indeed caused the spermatogenic failure.