WT1 deletion leading to severe 46,XY gonadal dysgenesis, Wilms tumor and gonadoblastoma: case report.

BACKGROUND: Heterozygous missense mutations in the WT1 gene that affect the function of the wild-type allele have been identified in Denys-Drash syndrome, which is characterized by severe gonadal dysgenesis, early-onset nephropathy and a predisposition to renal and gonadal cancer. Intron 9 splice-site mutations that influence the balance between WT1 isoforms cause a nearly similar phenotype, known as Frasier syndrome. Nonsense mutations and deletions only lead to WT1 haploinsufficiency and, hence, to less severe gonadal dysgenesis and late-onset nephropathy. WT1 analysis is mandatory in 46,XY gonadal dysgenesis with renal abnormality. PATIENT: We describe a newborn with 46,XY severe partial gonadal dysgenesis, in whom structural renal anomalies and proteinuria were excluded. Gonadectomy was performed at the age of 1 month and the microscopy was thought to be suggestive for a gonadoblastoma. At the age of 9 months, the patient presented with a bilateral Wilms tumor. RESULTS: We found a heterozygous WT1 whole-gene deletion but no other gene defects. CONCLUSIONS: This case description illustrates that a WT1 deletion might be associated with a more severe phenotype than previously thought. It also illustrates that, even in the absence of renal abnormality, it is recommended to test promptly for WT1 defects in 46,XY gonadal dysgenesis.

Mortality risk of untreated myosin-binding protein C-related hypertrophic cardiomyopathy: insight into the natural history.

OBJECTIVES: The goal of this study was to assess the mortality of hypertrophic cardiomyopathy (HCM), partly in times when the disease was not elucidated and patients were untreated. BACKGROUND: HCM is feared for the risk of sudden cardiac death (SCD). Insight in the natural history of the disorder is needed to design proper screening strategies for families with HCM. METHODS: In 6 large, 200-year multigenerational pedigrees (identified by using genealogical searches) and in 140 small (contemporary) pedigrees (first-degree relatives of the proband) with HCM caused by a truncating mutation in the myosin-binding protein C gene (n = 1,118), we determined all-cause mortality using the family tree mortality ratio method. The study's main outcome measure was the standardized mortality ratio (SMR). RESULTS: In the large pedigrees, overall mortality was not increased (SMR 0.86 [95% confidence interval (CI): 0.72 to 1.03]), but significant excess mortality occurred between 10 and 19 years (SMR 2.7 [95% CI: 1.2 to 5.2]). In the small families, the SMR was increased (SMR 1.5 [95% CI: 1.3 to 1.6]) [corrected] and excess mortality was observed between 10 and 39 years (SMR 3.2 [95% CI: 2.3 to 4.3]) and 50 and 59 years (SMR 1.9 [95% CI: 1.4 to 2.5]). CONCLUSIONS: We identified specific age categories with increased mortality risks in HCM families. The small, referred pedigrees had higher mortality risks than the large 200-year multigenerational pedigrees. Our findings support the strategy of starting cardiological and genetic screening in the first-degree relatives of a proband from 10 years onward and including persons in the screening at least until the age of 60 years. Screening of more distant relatives is probably most efficient between 10 and 19 years.

A comprehensive gene mutation screen in men with asthenozoospermia.

OBJECTIVE: To find novel genetic causes of asthenozoospermia by comprehensively screening known candidate genes derived from mouse models. DESIGN: Case-control study. SETTING: A fertility center based in an academic hospital. PATIENT(S): Thirty men with isolated asthenozoospermia. INTERVENTION(S): Screening nine candidate genes for mutations: ADCY10, AKAP4, CATSPER1, CATSPER2, CATSPER3, CATSPER4, GAPDHS, PLA2G6, and SLC9A10. To account for a possible effect of heterozygous mutations, assessing imprinting of all candidate genes by studying the expression pattern of heterozygous SNPs in testis biopsies of five unrelated men. MAIN OUTCOME MEASURE(S): Mutations found in patients only. RESULT(S): We identified 10 heterozygous asthenozoospermia-specific mutations in ADYC10 (n = 2), AKAP4 (n =1), CATSPER1 (n = 1), CATSPER2 (n = 1), CATSPER3 (n = 1), CATSPER4 (n = 3), and PLA2G6 (n = 1). These mutations were distributed over six patients. In silico analysis showed that 8 of the 10 mutations either had a negative BLOSUM score, were located in conserved residues, and/or were located in a functional domain. Expression analysis demonstrated that CATSPER1 and CATSPER4 are imprinted. CONCLUSION(S): Given their putative effect on protein structure, their location in conserved sequences or functional domains, and their absence in controls, the identified mutations may be a cause of asthenozoospermia in humans.

Mutations in the human BOULE gene are not a major cause of impaired spermatogenesis.

Mutation screening of the BOULE gene in 156 men with azoospermia or severe oligozoospermia revealed no relevant mutations; thus, mutations in BOULE can be eliminated as a major cause of impaired spermatogenesis.

Idiopathic impaired spermatogenesis: genetic epidemiology is unlikely to provide a short-cut to better understanding.

The aetiology of impaired spermatogenesis is unknown in the majority of subfertile men. From several studies of concordance for involuntary childlessness among men, we can conclude that there is a substantial familial component in male subfertility and that shared loci segregating through families can be assumed. We now know that deletions on the Y chromosome, which do not penetrate fully, account for some of these cases. There are good reasons to suspect that other cases result from mutations in genes located elsewhere in the genome. In this article, we discuss different approaches to unravelling the molecular basis of impaired spermatogenesis originating from genetic abnormalities in chromosomes other than the Y chromosome. Genetic mapping studies are in general a good approach to detect disease-causing genes that are segregating through a population; they can provide a shortcut to unravelling the biochemistry of a disease. In this paper, we explain our reasons for arguing that linkage and association studies are no promising means to identify the genes causing impaired spermatogenesis. We conclude that direct screening of candidate genes for mutations will be necessary to detect genes involved in impaired spermatogenesis. However, this approach requires studies of the biochemical pathways of normal and abnormal spermatogenesis. Since we have a poor understanding of these pathways, more research is needed into the biochemistry of spermatogenesis.

Absence of mutations in the PCI gene in subfertile men.

The molecular aetiology of male subfertility is still unknown in the majority of cases and it is thought that multiple genes are involved. One of the genes that might play a role in male reproductive function is the protein C inhibitor (PCI) gene. In mice the presence of PCI is an absolute requirement for reproduction. In this study we performed a mutation screen of the PCI gene in subfertile men with severe teratozoospermia or idiopathic azoospermia. Male partners of subfertile couples with idiopathic azoospermia (n = 27) or teratozoospermia (n = 34) and men with normozoospermia (n = 34) were screened for mutations in the PCI gene by direct sequencing. Nine nucleotide variants found in the patients were not present in the initial control group and were therefore screened in an additional control group of 80 men with normozoospermia by restriction fragment length polymorphism analysis. In addition, PCI antigen levels were measured in the seminal plasma of the patients in which a potential mutation was found. In total, three new variants were exclusively present in men with idiopathic azoospermia, but are not likely to have caused the patients' phenotypes. In addition, the PCI antigen levels in seminal plasma of these three patients were not decreased. The fact that we were not able to detect causal mutations in the PCI gene does not necessarily lead to the conclusion that the PCI protein is not involved in human male fertility, but the results of our study indicate that mutations in the human PCI gene are not a common cause of reduced semen parameters in men.

Familial clustering of impaired spermatogenesis: no evidence for a common genetic inheritance pattern.

BACKGROUND: The aetiology of impaired spermatogenesis is unknown in the majority of cases. Evidence of a contribution of genetic factors is still scarce. Therefore, the aim of our study was to assess whether male factor subfertility due to impaired spermatogenesis has a familial component and to test different genetic models of inheritance. METHODS: Cases were all men with severe idiopathic impaired spermatogenesis attending our fertility clinic from January 1998 until December 2001. Controls were all men with normozoospermia attending our fertility clinic in the same period. Family data were collected from the medical records and by additional interviews of the probands. If subfertility of a first-degree relative was mentioned, permission was sought to contact the affected family member in order to obtain all medical information available, including the results of semen analyses. RESULTS: In total, 160 patients and 285 controls were included in the analysis. Family size and number of brothers and sisters were equally distributed in both groups. In the patient group, 1.63% of the brothers who had tried to father a child were mentioned to be subfertile compared to 5.8% in the control group [odds ratio 3.18 (95% confidence interval 1.59-6.37)]. The subfertility among the brothers in the patient group was more often due to reduced semen parameters compared to the control group. The data did not fit with frequent autosomal dominant or recessive segregation. CONCLUSION: Male factor subfertility due to impaired spermatogenesis appears to cluster in families. Our data suggests that heritable genetic factors play a role in a limited number of cases. Impaired spermatogenesis is not caused by a common genetic defect, but is most likely a complex disease in which several different factors play a role.

Chromosomal region 11p15 is associated with male factor subfertility.

The molecular aetiology of male factor subfertility, due to impaired spermatogenesis, is still unknown in the majority of cases. It is thought to be a complex disorder in which multiple genes are implicated. Cryptorchidism and reduced fecundity are symptoms in male Beckwith-Wiedemann patients and the ZNF214 and ZNF215 genes, localized on chromosomal region 11p15, are associated with this syndrome. We hypothesized that the ZNF214 and ZNF215 genes, which are predominantly expressed in the testis, could be involved in male factor subfertility in patients with idiopathic impaired spermatogenesis or in patients with impaired spermatogenesis due to cryptorchidism. Male partners of subfertile couples with idiopathic azoo- or severe oligozoospermia, male partners with azoo- or severe oligozoospermia and cryptorchidism in their medical history and men with normozoospermia were screened for nine single nucleotide polymorphisms in the ZNF214 and ZNF215 genes. An association study was performed based on allele and estimated haplotype frequencies. Statistically significant differences in allele frequencies and in estimated haplotype frequencies were found in both patient groups compared with controls. Thereafter, both genes were screened for mutations in all patients by PCR and single strand conformation polymorphism analysis. Aberrant patterns were confirmed by DNA sequencing. Mutation analysis in ZNF214 and ZNF215 revealed five new variants in the patients that were not present in the controls. At least three of these mutations were inherited from the mother. Our results suggest that chromosomal region 11p15 is associated with male factor subfertility due to impaired spermatogenesis with and without cryptorchidism.

Expression analysis of subtractively enriched libraries (EASEL): a widely applicable approach to the identification of differentially expressed genes.

A variety of methods for high throughput analysis of differential gene expression has been developed over the past years. We have implemented the EASEL technique that adds flexibility, efficiency and wide-applicability to these methods. The EASEL procedure is unique as it integrates several well established techniques and thereby offers a combination of subtractive hybridization of 3' cDNA ends with macroarrays analysis and Serial Analysis of Gene Expression (SAGE). In addition, once a set of interesting, differentially expressed genes is identified, the material required for follow up studies to test the hypothesis that the gene is truly involved in the process of interest is readily available. In this report, we first present a step-by-step validation of the procedure, since several of the incorporated steps had to be tailored to meet specific requirements and implied drastic modifications of the original methods. Secondly, we applied EASEL to the identification of up-regulated gene products in the outflow tract region of the embryonic rat heart. Here we provide evidence that at least two among the differentially expressed genes detected, follistatin-like protein gene and membrane type 1-metallo proteinase gene, are selectively up-regulated in the outflow tract, suggesting their involvement in the development of this region during embryogenesis.