Dooren, M.F. van

SDHA immunohistochemistry detects germline SDHA gene mutations in apparently sporadic paragangliomas and pheochromocytomas (Article)

2011-09-01T00:00:00Z

Context: Pheochromocytoma-paraganglioma syndrome is caused by mutations in SDHB, SDHC, and SDHD, encoding subunits of succinate dehydrogenase (SDH), and in SDHAF2, required for flavination of SDHA. A recent report described a patient with an abdominal paraganglioma, immunohistochemically negative for SDHA, and identified a causal germline mutation in SDHA. Objective: In this study, we evaluated the significance of SDHA immunohistochemistry in the identification of new patients with SDHA mutations. Setting: This study was performed in the Erasmus Medical Center in Rotterdam (The Netherlands) and the Université Paris Descartes in Paris (France). Methods: We investigated 316 pheochromocytomas and paragangliomas for SDHA expression. Sequence analysis of SDHA was performed on all tumors that were immunohistochemically negative for SDHA and on a subset of tumors immunohistochemically positive for SDHA. Results: Six tumors were immunohistochemically negative for SDHA. Four tumors from Dutch patients showed a germline c.91C→T SDHA gene mutation (p.Arg31X). Another tumor (from France) carried a germline SDHA missense mutation c.1753C→T (p.Arg585Trp). Loss of the wildtype SDHA allele was confirmed by loss of heterozygosity analysis. Sequence analysis of 35 SDHA immunohistochemically positive tumors did not reveal additional SDHA mutations. Conclusions: Our results demonstrate that SDHA immunohistochemistry on paraffin-embedded tumors can reveal the presence of SDHA germline mutations and allowed the identification of SDHA-related tumors in at least 3% of patients affected by apparently sporadic (para)sympathetic paragangliomas and pheochromocytomas. Copyright

Evaluation of the XRCC1 gene as a phenotypic modifier in BRCA1/2 mutation carriers. Results from the consortium of investigators of modifiers of BRCA1/BRCA2 (Article)

2011-05-01T00:00:00Z

Background: Single-nucleotide polymorphisms (SNPs) in genes involved in DNA repair are good candidates to be tested as phenotypic modifiers for carriers of mutations in the high-risk susceptibility genes BRCA1 and BRCA2. The base excision repair (BER) pathway could be particularly interesting given the relation of synthetic lethality that exists between one of the components of the pathway, PARP1, and both BRCA1 and BRCA2. In this study, we have evaluated the XRCC1 gene that participates in the BER pathway, as phenotypic modifier of BRCA1 and BRCA2. Methods: Three common SNPs in the gene, c.-77C>T (rs3213245) p.Arg280His (rs25489) and p.Gln399Arg (rs25487) were analysed in a series of 701 BRCA1 and 576 BRCA2 mutation carriers. Results: An association was observed between p.Arg280His-rs25489 and breast cancer risk for BRCA2 mutation carriers, with rare homozygotes at increased risk relative to common homozygotes (hazard ratio: 22.3, 95% confidence interval: 14.3-34, P<0.001). This association was further tested in a second series of 4480 BRCA1 and 3016 BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1 and BRCA2.Conclusions and inteNo evidence of association was found when the larger series was analysed which lead us to conclude that none of the three SNPs are significant modifiers of breast cancer risk for mutation carriers.

Further clinical and molecular delineation of the 9q subtelomeric deletion syndrome supports a major contribution of EHMT1 haploinsufficiency to the core phenotype (Article)

2009-09-01T00:00:00Z

Background: The 9q subtelomeric deletion syndrome (9qSTDS) is clinically characterised by moderate to severe mental retardation, childhood hypotonia and facial dysmorphisms. In addition, congenital heart defects, urogenital defects, epilepsy and behavioural problems are frequently observed. The syndrome can be either caused by a submicroscopic 9q34.3 deletion or by intragenic EHMT1 mutations leading to haploinsufficiency of the EHMT1 gene. So far it has not been established if and to what extent other genes in the 9q34.3 region contribute to the phenotype observed in deletion cases. This study reports the largest cohort of 9qSTDS cases so far. Methods and results: By a multiplex ligation dependent probe amplification (MLPA) approach, the authors identified and characterised 16 novel submicroscopic 9q deletions. Direct sequence analysis of the EHMT1 gene in 24 patients exhibiting the 9qSTD phenotype without such deletion identified six patients with an intragenic EHMT1 mutation. Five of these mutations predict a premature termination codon whereas one mutation gives rise to an amino acid substitution in a conserved domain of the protein. Conclusions: The data do not provide any evidence for phenotype-genotype correlations between size of the deletions or type of mutations and severity of clinical features. Therefore, the authors confirm the EHMT1 gene to be the major determinant of the 9qSTDS phenotype. Interestingly, five of six patients who had reached adulthood had developed severe psychiatric pathology, which may indicate that EHMT1 haploinsufficiency is associated with neurodegeneration in addition to neurodevelopmental defect.

Application of molecular cytogenetic techniques to clarify apparently balanced complex chromosomal rearrangements in two patients with an abnormal phenotype: Case report (Article)

2009-08-27T00:00:00Z

Background. Complex chromosomal rearrangements (CCR) are rare cytogenetic findings that are difficult to karyotype by conventional cytogenetic analysis partially because of the relative low resolution of this technique. High resolution genotyping is necessary in order to identify cryptic imbalances, for instance near the multiple breakpoints, to explain the abnormal phenotype in these patients. We applied several molecular techniques to elucidate the complexity of the CCRs of two adult patients with abnormal phenotypes. Results. Multicolour fluorescence in situ hybridization (M-FISH) showed that in patient 1 the chromosomes 1, 10, 15 and 18 were involved in the rearrangement whereas for patient 2 the chromosomes 5, 9, 11 and 13 were involved. A 250 k Nsp1 SNP-array analysis uncovered a deletion in chromosome region 10p13 for patient 1, harbouring 17 genes, while patient 2 showed no pathogenic gains or losses. Additional FISH analysis with locus specific BAC-probes was performed, leading to the identification of cryptic interstitial structural rearrangements in both patients. Conclusion. Application of M-FISH and SNP-array analysis to apparently balanced CCRs is useful to delineate the complex chromosomal rearrangement in detail. However, it does not always identify cryptic imbalances as an explanation for the abnormal phenotype in patients with a CCR.

Premature ovarian failure and gene polymorphisms (Article)

2009-08-01T00:00:00Z

PURPOSE OF REVIEW: Premature ovarian insufficiency (POI) is a common disorder affecting approximately 1% of women under the age of 40 years. Until now, research aiming to identify genetic causes of POI was mostly based on candidate gene approaches. Recently, several genes have been identified using this approach, and genome-wide searches were conducted. In this review, we discuss these studies and propose future direction for further research in this field. RECENT FINDINGS: Candidate gene approach revealed NOBOX, NR5A1, FIGLA and PGRMC1 as POI-genes. Genome-wide searches (linkage and association studies) are revealing new loci/genes as well. SUMMARY: The role in POI for most reported candidate genes is still under discussion. Because POI families with several affected cases are rare, linkage studies are difficult to conduct; however, the reported loci needs further exploration/replication. In the only genome-wide association studies conducted, the patient cohort used is very small and the reported results are awaiting replication. Unravelling the genetics of POI will need the establishment of a large international consortium.

A genome-wide linkage scan in a Dutch family identifies a premature ovarian failure susceptibility locus (Article)

2008-12-01T00:00:00Z

BACKGROUND: Premature ovarian failure (POF) is characterized by elevated gonadotrophins and amenorrhea before the age of 40 years and occurs approximately in 1% of women. POF etiology is highly heterogeneous with a wide spectrum of etiological pathogenic mechanisms including genetic causes. These mostly involve numerical, structural or monogenic defects on the X-chromosome. Mutations in a small number of autosomal genes (such as FOXL2 and NOBOX) have been identified as a cause of POF. However, in most cases, the disease underlying mechanisms are largely unknown. METHODS: We performed a genome-wide linkage analysis in a relatively large Dutch family with seven patients suffering from POF, showing a dominant pattern of inheritance. A genome-wide analysis, using 50K single nucleotide polymorphism arrays, was combined with conventional parametric linkage analysis. RESULTS: We identified three genomic regions on chromosomes 5, 14 and 18 yielding suggestive linkage (multipoint LOD score of 2.4 for each region). After inclusion of one elder unaffected family member, only the region on chromosome 5 remains as a putative POF locus. In addition, we investigated a second family (three living patients over three generations) for the regions on chromosome 5, 14 and 18. Haplotype analysis supported only the locus on chromosome 5q14.1-q15. CONCLUSION: We performed the first genome-wide linkage search in familial POF and identified a region on chromosome 5q14.1-q15, which may harbor a novel POF susceptibility gene.

Non-VACTERL-type anomalies are frequent in patients with esophageal atresia/tracheo-esophageal fistula and full or partial VACTERL association (Article)

2008-03-01T00:00:00Z

BACKGROUND: The VACTERL association is the nonrandom co-occurrence of Vertebral anomalies, Anal atresia, Cardiovascular malformations, Tracheo-esophageal fistula (TEF) and/or Esophageal atresia (EA), Renal anomalies, and/or Limb-anomalies. The full phenotype of patients with EA/TEF and other anomalies of the VACTERL spectrum of defects association is not well described in the literature. METHODS: Data on patients with EA/TEF seen in two pediatric surgical centers in the Netherlands between January 1988 and August 2006 were evaluated for defects of the VACTERL spectrum as well as non-VACTERL-type defects. The presence of two or more defects of the VACTERL spectrum in addition to EA/TEF was the criterion for inclusion in this study. A detailed description was made of all defects. RESULTS: Of 463 patients with EA and/or TEF, 107 (23.1%) fulfilled the inclusion criterion, of which seventeen cases had a recognized etiology and were excluded, leaving 90 cases (19.4%) for analysis. Other than the esophagus and the trachea, the vertebrae/ribs and the cardiovascular system were most commonly affected (68.9 and 65.6%, respectively). Interestingly, 70% of cases had additional non-VACTERL-type defects, with high occurrences for single umbilical artery (20%), genital defects (23.3%), and respiratory tract anomalies (13.3%). CONCLUSIONS: Many patients with EA/TEF and at least two other defects of the VACTERL spectrum also display non-VACTERL-type congenital anomalies.

Environmental factors in the etiology of esophageal atresia and congenital diaphragmatic hernia: Results of a case-control study (Article)

2008-03-01T00:00:00Z

BACKGROUND: Esophageal atresia with or without tracheoesophageal fistula (EA/TEF) and congenital diaphragmatic hernia (CDH) are severe congenital anomalies. Their etiologies are mostly unknown and are thought to be multifactorial. No specific environmental factors have consistently been described as risk factors. METHODS: In a study conducted during the years 2000 to 2004 in a pediatric surgical referral center in the Netherlands, parents of children with EA/TEF or with CDH of the Bochdalek type and parents of a group of children without major birth defects filled out a questionnaire about possible exposure to environmental risk factors during the period from 1 month before conception to the end of the first trimester of pregnancy. Children with chromosomal anomalies were excluded. RESULTS: Questionnaires were returned for 47 out of 64 cases (73%) with EA/TEF, for 63 out of 77 cases (82%) with CDH, and for 202 out of 243 controls (83%). In EA/TEF, maternal age was borderline significantly higher than in controls (32.2 vs. 30.6 years, p = .05). Contact with herbicides or insecticides was associated with EA/TEF in univariate analysis (OR 2.0; 95% CI: 1.0-4.1) and in multivariate analysis, although of borderline significance. In univariate analysis, CDH was significantly associated with maternal use of alcohol (OR 2.9; 95% CI: 1.6-5.2). CONCLUSIONS: We found a significant association between maternal alcohol use around the time of conception and CDH. A possible explanation might be the effect of alcohol on the retinoic acid pathway. An association was found between contact with herbicides or insecticides and EA/TEF.

Congenital diaphragmatic hernia associated with duplication of 11q23-qter. (Article)

2006-07-15T00:00:00Z

Congenital diaphragmatic hernia (CDH) is a relatively common birth defect with a high mortality. Although little is known about its etiology, there is increasing evidence for a strong genetic contribution. Both numerical and structural chromosomal abnormalities have been described in patients with CDH. Partial trisomy 11q and partial trisomy 22 associated with the common t(11;22) has been reported in several cases of CDH. It has been assumed that the diaphragmatic defect seen in these individuals was primarily due to duplication of material from chromosome 22q11. However, in this report we describe a family with a t(11;12) in which one of two brothers with partial trisomy 11q has a left sided posterolateral CDH. This is the second case of CDH in partial trisomy 11q due to an unbalanced translocation other than t(11;22). Using array-based comparative genomic hybridization and fluorescent in situ hybridization, we mapped the breakpoints in both brothers and their mother who is a balanced translocation carrier. Our results suggest that duplication of one or more genes on a approximately 19 Mb region of 11q23.3-qter predisposes to the development of CDH. These effects may be the primary cause of CDH in individuals t(11;22) or may be additive to effects from the duplication of chromosome 22 material. We also conclude that the partial trisomy 11q syndrome has a variable phenotype and that CDH should be added to the spectrum of anomalies that can be present in this syndrome.

Distal angiogenesis: a new concept for lung vascular morphogenesis. (Article)

2005-01-01T00:00:00Z

Although several molecular players have been described that play a role during the early phases of lung development, it is still unknown how the vasculature develops in relation to the airways. Two opposing models describe development of lung vasculature: one suggests that both vasculogenesis and angiogenesis are involved, whereas the second describes vasculogenesis as the primary mechanism. Therefore, we examined the development of the murine pulmonary vasculature through a morphological analysis from the onset of lung development [9.5 days postcoital (dpc)] until the pseudoglandular stage (13.5 dpc). We analyzed fetal lungs of Tie2-LacZ transgenic mice as well as serial sections of wild-type lungs stained with endothelial-specific antibodies (Flk-1, Fli-1, and PECAM-1). Embryos were processed with intact blood circulation to maintain the integrity of the vasculature; hence individual vessels could be identified with accuracy through serial section analysis. Furthermore, circulating primitive erythrocytes, formed exclusively by the blood islands in the yolk sac, are trapped in vessels during fixation, which proves the connection with the embryonic circulation. We report that from the first morphological sign of lung development, a clear vascular network exists that is in contact with the embryonic circulation. We propose distal angiogenesis as a new concept for early pulmonary vascular morphogenesis. In this model, capillary networks surround the terminal buds and expand by formation of new capillaries from preexisting vessels as the lung bud grows. The fact that at an early embryonic stage a complete vascular network exists may be important for the general understanding of embryonic development.

Congenital diaphragmatic hernia and chromosome 15q26: determination of a candidate region by use of fluorescent in situ hybridization and array-based comparative genomic hybridization (Article)

2005-01-01T00:00:00Z

Congenital diaphragmatic hernia (CDH) has an incidence of 1 in 3,000 births and a high mortality rate (33%-58%). Multifactorial inheritance, teratogenic agents, and genetic abnormalities have all been suggested as possible etiologic factors. To define candidate regions for CDH, we analyzed cytogenetic data collected on 200 CDH cases, of which 7% and 5% showed numerical and structural abnormalities, respectively. This study focused on the most frequent structural anomaly found: a deletion on chromosome 15q. We analyzed material from three of our patients and from four previously published patients with CDH and a 15q deletion. By using array-based comparative genomic hybridization and fluorescent in situ hybridization to determine the boundaries of the deletions and by including data from two individuals with terminal 15q deletions but without CDH, we were able to exclude a substantial portion of the telomeric region from the genetic etiology of this disorder. Moreover, one patient with CDH harbored a small interstitial deletion. Together, these findings allowed us to define a minimal deletion region of approximately 5 Mb at chromosome 15q26.1-26.2. The region contains four known genes, of which two--NR2F2 and CHD2--are particularly intriguing gene candidates for CDH.

Congenital diaphragmatic hernia and situs inversus totalis (Article)

2004-01-01T00:00:00Z