Biomedical subjects

B A Oostra

Publications and source records attributed to B A Oostra.

At least 19 recordsLinked to original sources

PubMed2006

Elevated Fmr1 mRNA levels and reduced protein expression in a mouse model with an unmethylated Fragile X full mutation.

The human FMR1 gene contains a CGG repeat in its 5' untranslated region. The repeat length in the normal population is polymorphic (5-55 CGG repeats). Lengths beyond 200 CGGs (full mutation) result in the absence of the FMR1 gene product, FMRP, through abnormal methylation and gene silencing. This causes Fragile X syndrome, the most common inherited form of mental retardation. Elderly carriers of the premutation, defined as a repeat length between 55 and 200 CGGs, can develop a progressive neurodegenerative syndrome: Fragile X-associated tremor/ataxia syndrome (FXTAS). In FXTAS, FMR1 mRNA levels are elevated and it has been hypothesised that FXTAS is caused by a pathogenic RNA gain-of-function mechanism. We have developed a knock in mouse model carrying an expanded CGG repeat (98 repeats), which shows repeat instability and displays biochemical, phenotypic and neuropathological characteristics of FXTAS. Here, we report further repeat instability, up to 230 CGGs. An expansion bias was observed, with the largest expansion being 43 CGG units and the largest contraction 80 CGG repeats. In humans, this length would be considered a full mutation and would be expected to result in gene silencing. Mice carrying long repeats ( approximately 230 CGGs) display elevated mRNA levels and decreased FMRP levels, but absence of abnormal methylation, suggesting that modelling the Fragile X full mutation in mice requires additional repeats or other genetic manipulation.

Alleles↗

PubMed2006

Genetic and clinical analysis of a large Dutch Gilles de la Tourette family.

Gilles de la Tourette syndrome is a complex neuropsychiatric disorder, which becomes evident in childhood between the ages of 2 and 15 years. Tourette syndrome is defined by the occurrence of a large range and variable number of unwanted repetitive simple or complex motor and vocal tics that start in childhood and follow a waxing and waning course. A major gene for this syndrome has not yet been identified, probably owing to both genetic and phenotypic heterogeneity of this disease. This article describes the clinical evaluation of patients and family members in a large Dutch Gilles de la Tourette Syndrome pedigree and the decisions encountered with respect to phenotyping. The importance of an accurate definition of the Tourette phenotype is discussed, which is highly important for reliable genetic linkage and association studies. Subsequent linkage analysis resulted in three linkage peaks on different chromosomes 3q, 9q, and 13q. Multipoint analysis resulted in a single linkage peak with logarithm of odds score 2.55 with marker D3S1311 on chromosome 3q.

Adolescent↗

PubMed2006

Heritability of serum iron, ferritin and transferrin saturation in a genetically isolated population, the Erasmus Rucphen Family (ERF) Study.

BACKGROUND: Iron has been implicated in the pathogenesis of various disorders. Mutations in the HFE gene are associated with an increase in serum iron parameters. The aim of this study was to estimate the heritability in serum iron parameters explained by HFE. METHODS: Ninety families (980 subjects) were included in the present analysis. Heritability estimation was conducted using the variance component method. The likelihood ratio test was used to compare models. Phenotypic and genetic correlations between serum iron parameters were calculated. RESULTS: The heritability (h(2) +/- SE) estimates were 0.23 +/- 0.07 (p < 0.0001) for iron, 0.29 +/- 0.09 (p < 0.0001) for ferritin and 0.28 +/- 0.07 (p < 0.0001) for transferrin saturation while adjusting for age, age(2) and sex. The HFE genotypes explained between 2 to 6% of the sex and age-adjusted variance in serum iron, ferritin and transferrin saturation. There was a high genetic correlation between serum iron parameters, suggesting pleiotropy between these traits. CONCLUSION: A substantial proportion of the variance of iron, ferritin and transferrin saturation can be explained by additive genetic effects, independent of sex and age. The HFE genotypes explained a considerable proportion of serum iron parameters and may be an important factor in the complex iron network.

Female↗

PubMed2006

Cerebrovascular risk factors do not contribute to genetic variance of cognitive function: the ERF study.

Impaired cognition in later life may result from Alzheimer's disease-related pathology, but also from vascular pathology. We studied to what extent vascular risk explained heritability of cognition in 780 individuals, related in one extended pedigree in a genetically isolated population, in the ERF study. Heritability was estimated using variance components modelling (SOLAR). Univariate analyses included models with and without vascular disease; bivariate analyses included both cognitive and vascular traits, such as blood pressure, serum glucose or lipids. Heritability for immediate and delayed recall, recognition, semantic fluency, Trail making B and Stroop tests was significant, with estimates from 0.16 to 0.36. Vascular factors did not affect cognitive functions, except immediate recall and the Stroop test. Heritability estimates did not change significantly when adjusted for vascular disease. We found no genetic correlation between cognition and vascular traits. Therefore, in this population vascular disease is mildly associated with cognitive dysfunction, and in those with vascular disease, the underlying genetic risk factors are not likely to account for the genetic variation in cognition at adult age.

Adult↗

PubMed2006

ACE polymorphisms.

Angiotensin converting enzyme (ACE) plays an essential role in two physiological systems, one leading to the production of angiotensin II and the other to the degradation of bradykinin. The wide distribution and multifunctional properties of these peptides suggest that ACE could be involved in various pathophysiological conditions. The discovery that ACE levels are under genetic control ushered in a new era of investigation; most studies focused on an insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene as a marker for a functional polymorphism. Recently, many single nucleotide polymorphisms were detected in the gene and the search for the locations of functional polymorphisms became a topic of extensive investigation. Nevertheless, association studies on the I/D polymorphism and clinical outcomes continued, mostly with conflicting results. This article reviews the current state of knowledge regarding ACE polymorphisms and suggests that a functional polymorphism is most likely located between intron 18 and the 3' UTR. The potential existence of another functional polymorphism in the 5' UTR, however, cannot be excluded. This review also presents an overview of ACE function in different pathophysiological systems, and summarizes previous reports on ACE and clinical outcomes. Although findings on the I/D polymorphism and disorders like diabetic nephropathy and Alzheimer disease can be considered conclusive, reports on most of the cardiovascular phenotypes are still controversial. Genotypic and phenotypic misclassifications, insufficient power in some studies, and the presence of interaction with other genes or environmental factors are possible explanations for the contradictory findings.

Humans↗

PubMed2006

Heritability of fasting glucose levels in a young genetically isolated population.

AIMS/HYPOTHESIS: The heritability of fasting glucose levels in Northern European populations has been examined previously in twins and samples of small pedigrees. In this study the heritability of fasting plasma glucose (FPG) was estimated in participants in the Erasmus Rucphen Family study, who were members of a single pedigree from a young genetic isolate. We also studied the relationship between FPG and components of the metabolic syndrome. METHODS: FPG, lipid, blood pressure and body composition measurements were completed for 852 participants without diabetic medication. The most significant predictors of FPG were used as covariates in heritability estimation. The sibship effect, which is a composite of genetic dominance and shared early-life environmental effects, was included as a random effect. RESULTS: The age- and sex-adjusted heritability of log normal-transformed FPG was 36.6%. When further adjusted for metabolic risk factors, namely body composition parameters, systolic blood pressure, triglycerides and cholesterol: HDL ratio, the heritability estimate rose to 42.8%. After adjustment for the sibship effect, the additive component of heritability was estimated to be 28.3% (age- and sex-adjusted) and 24.9% (full model). CONCLUSIONS/INTERPRETATION: Genes control a significant proportion of the variance in FPG levels. Adjustment for other metabolic risk factors did not substantially change the heritability estimate, which suggests that a large part of the variance in FPG levels is due to genes that act through pathways that are independent of those controlling body composition, blood pressure and lipid levels.

Blood Glucose↗

PubMed2006

A novel susceptibility locus for Hirschsprung's disease maps to 4q31.3-q32.3.

We report on a multigenerational family with isolated Hirschsprung's disease (HSCR). Five patients were affected by either short segment or long segment HSCR. The family consists of two main branches: one with four patients (three siblings and one maternal uncle) and one with one patient. Analysis of the RET gene, the major gene involved in HSCR susceptibility, revealed neither linkage nor mutations. A genome wide linkage analysis was performed, revealing suggestive linkage to a region on 4q31-q32 with a maximum parametric multipoint LOD score of 2.7. Furthermore, non-parametric linkage (NPL) analysis of the genome wide scan data revealed a NPL score of 2.54 (p = 0.003) for the same region on chromosome 4q (D4S413-D4S3351). The minimum linkage interval spans a region of 11.7 cM (12.2 Mb). No genes within this chromosomal interval have previously been implicated in HSCR. Considering the low penetrance of disease in this family, the 4q locus may be necessary but not sufficient to cause HSCR in the absence of modifying loci elsewhere in the genome. Our results suggest the existence of a new susceptibility locus for HSCR at 4q31.3-q32.3.

Chromosome Mapping↗

PubMed2005

The generation of a conditional Fmr1 knock out mouse model to study Fmrp function in vivo.

The FMR1 gene, mutated in Fragile X syndrome patients, has been modeled in mice with a neomycin cassette inserted in exon 5 of the mouse Fmr1 gene creating an Fmr1 knockout (Fmr1 KO) allele. This results in animals lacking Fmr1 protein (Fmrp) expression in all tissues. We have created a new, more versatile Fmr1 in vivo KO model (Fmr1 KO2) and generated conditional Fmr1 KO (CKO) mice by flanking the promoter and first exon of Fmr1 with lox P sites. This enables us to create a null allele in specific cell types and at specific time points by crossing Fmr1 CKO mice with tissue specific or inducible cre-recombinase expressing mice. The new Fmr1 KO2 line does not express any Fmrp and also lacks detectable Fmr1 transcripts. Crossing the Fmr1 CKO line with a Purkinje cell-specific cre-recombinase expresser produces mice that are null for Fmr1 in Purkinje neurons but wild type in all other cell types.

Animals↗

PubMed2005

Heritability of the function and structure of the arterial wall: findings of the Erasmus Rucphen Family (ERF) study.

BACKGROUND AND PURPOSE: Using 930 individuals connected in a single pedigree from an isolated population, participants of the Erasmus Rucphen Family (ERF) study, we investigated the heritability of carotid-femoral pulse wave velocity (PWV), carotid intima media thickness (IMT), and carotid plaque score. METHODS: PWV was measured between the carotid and femoral arteries as an indicator of aortic stiffness. Common carotid IMT and plaque score, quantifying alterations in arterial wall structure, were measured by ultrasonography. RESULTS: All 3 traits were significantly associated with classic cardiovascular risk factors. Age- and gender-adjusted heritability estimates were 0.36 for PWV, 0.41 for carotid IMT, and 0.28 for plaque score. After adjustment for appropriate risk factors, the heritabilities were 0.26, 0.35, and 0.21 for PWV, IMT, and plaque score, respectively. All heritability estimates were statistically significant (P<0.001). Taking into account different proportions of variance associated with covariates for each trait, genetic factors explained &12% of the total variability for each of the phenotypes. CONCLUSIONS: To our knowledge, this is the first report on the heritability of PWV. The heritability estimates of IMT and plaque score were similar to those in previous reports. We conclude that genetic factors significantly contribute to arterial structure and function in this isolated population, presenting the opportunity to locate susceptibility genes related to cardiovascular disorders.

Adult↗

PubMed2005

Familial aggregation, the PDE4D gene, and ischemic stroke in a genetically isolated population.

OBJECTIVE: The purpose of this investigation was to study the familial aggregation of ischemic stroke and the association between the PDE4D gene and ischemic stroke. METHODS: The study was performed in an isolated population in The Netherlands, where the authors identified 91 patients with ischemic stroke. Ischemic stroke was subclassified in large- and small-vessel infarction. The authors calculated kinship and inbreeding coefficients and genotyped all patients for three single-nucleotide polymorphisms (SNPs) in the PDE4D gene. RESULTS: The proportion of related pairs was higher in patients with ischemic stroke (68.8%) compared with controls (30.7%; p < 0.001). For large-vessel infarction, the proportion of related pairs was higher (71%) compared with small-vessel infarction (62.8%; p < 0.001). Familial aggregation was strongest for patients with early onset (age at onset < 45 years). All stroke groups were significantly more inbred compared with controls. In inbred individuals, the C allele of SNP45 increased the risk of small-vessel infarction 4.8 times (95% CI 1.1 to 22.3) compared with controls (p = 0.04). The T allele of SNP39 increased the risk of small-vessel infarction 6.3 times (95% CI 1.4 to 28.7) compared with controls (p = 0.02). No associations were found for large-vessel stroke. CONCLUSIONS: There was familial aggregation of ischemic stroke and a difference in degree of familial clustering between stroke subtypes. The authors also found that the PDE4D gene is significantly associated with small-vessel infarction in inbred individuals.

3',5'-Cyclic-AMP Phosphodiesterases↗

PubMed2005

Deletion of FMR1 in Purkinje cells enhances parallel fiber LTD, enlarges spines, and attenuates cerebellar eyelid conditioning in Fragile X syndrome.

Absence of functional FMRP causes Fragile X syndrome. Abnormalities in synaptic processes in the cerebral cortex and hippocampus contribute to cognitive deficits in Fragile X patients. So far, the potential roles of cerebellar deficits have not been investigated. Here, we demonstrate that both global and Purkinje cell-specific knockouts of Fmr1 show deficits in classical delay eye-blink conditioning in that the percentage of conditioned responses as well as their peak amplitude and peak velocity are reduced. Purkinje cells of these mice show elongated spines and enhanced LTD induction at the parallel fiber synapses that innervate these spines. Moreover, Fragile X patients display the same cerebellar deficits in eye-blink conditioning as the mutant mice. These data indicate that a lack of FMRP leads to cerebellar deficits at both the cellular and behavioral levels and raise the possibility that cerebellar dysfunctions can contribute to motor learning deficits in Fragile X patients.

Animals↗

PubMed2005

Early-onset parkinsonism associated with PINK1 mutations: frequency, genotypes, and phenotypes.

OBJECTIVE: To assess the prevalence, nature, and associated phenotypes of PINK1 gene mutations in a large series of patients with early-onset (<50 years) parkinsonism. METHODS: The authors studied 134 patients (116 sporadic and 18 familial; 77% Italian) and 90 Italian controls. The whole PINK1 coding region was sequenced from genomic DNA; cDNA was analyzed in selected cases. RESULTS: Homozygous pathogenic mutations were identified in 4 of 90 Italian sporadic cases, including the novel Gln456Stop mutation; single heterozygous truncating or missense mutations were found in another 4 Italian sporadic cases, including two novel mutations, Pro196Leu and Gln456Stop. Pathogenic mutations were not identified in the familial cases. Novel (Gln115Leu) and known polymorphisms were identified with similar frequency in cases and controls. In cases carrying single heterozygous mutation, cDNA analysis detected no additional mutations, and revealed a major pathogenic effect at mRNA level for the mutant C1366T/Gln456Stop allele. All patients with homozygous mutations had very early disease onset, slow progression, and excellent response to l-dopa, including, in some, symmetric onset, dystonia at onset, and sleep benefit, resembling parkin-related disease. Phenotype in patients with single heterozygous mutation was similar, but onset was later. CONCLUSIONS: PINK1 homozygous mutations are a relevant cause of disease among Italian sporadic patients with early-onset parkinsonism. The role of mutations found in single heterozygous state is difficult to interpret. Our study suggests that, at least in some patients, these mutations are disease causing, in combination with additional, still unknown factors.

Adolescent↗

PubMed2005

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

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.

Abnormalities, Multiple↗

PubMed2005

Studying the genetics of Hirschsprung's disease: unraveling an oligogenic disorder.

Hirschsprung's disease is characterized by the absence of ganglion cells in the myenteric and submucosal plexuses of the gastrointestinal tract. Genetic dissection was successful as nine genes and four loci for Hirschsprung's disease susceptibility were identified. Different approaches were used to find these loci such as classical linkage in large families, identity by descent mapping in an inbred kindred, candidate gene approaches based on naturally occurring mutant mice models, and finally the use of model-free linkage and association analyzes. In this study, we review the identification of genes and loci involved in the non-syndromic common form and syndromic Mendelian forms of Hirschsprung's disease. The majority of the identified genes are related to Mendelian syndromic forms of Hirschsprung's disease. The non-Mendelian inheritance of sporadic non-syndromic Hirschsprung's disease proved to be complex; involvement of multiple loci was demonstrated in a multiplicative model. We discuss the practical implications of the elucidation of genes associated with Hirschsprung's disease susceptibility for genetic counseling. Finally, we speculate on possible strategies to identify new genes for Hirschsprung's disease.

Family Health↗

PubMed2005

The G6055A (G2019S) mutation in LRRK2 is frequent in both early and late onset Parkinson's disease and originates from a common ancestor.

BACKGROUND: Mutations in the gene Leucine-Rich Repeat Kinase 2 (LRRK2) were recently identified as the cause of PARK8 linked autosomal dominant Parkinson's disease. OBJECTIVE: To study recurrent LRRK2 mutations in a large sample of patients from Italy, including early (<50 years) and late onset familial and sporadic Parkinson's disease. RESULTS: Among 629 probands, 13 (2.1%) were heterozygous carriers of the G2019S mutation. The mutation frequency was higher among familial (5.1%, 9/177) than among sporadic probands (0.9%, 4/452) (p<0.002), and highest among probands with one affected parent (8.7%, 6/69) (p<0.001). There was no difference in the frequency of the G2019S mutation in probands with early v late onset disease. Among 600 probands, one heterozygous R1441C but no R1441G or Y1699C mutations were detected. None of the four mutations was found in Italian controls. Haplotype analysis in families from five countries suggested that the G2019S mutation originated from a single ancient founder. The G2019S mutation was associated with the classical Parkinson's disease phenotype and a broad range of onset age (34 to 73 years). CONCLUSIONS: G2019S is the most common genetic determinant of Parkinson's disease identified so far. It is especially frequent among cases with familial Parkinson's disease of both early and late onset, but less common among sporadic cases. These findings have important implications for diagnosis and genetic counselling in Parkinson's disease.

Adult↗

PubMed2004

Brachydactyly and short stature in a kindred with early-onset parkinsonism.

In a Dutch kindred we have identified a deletion of the DJ-1 gene, leading to autosomal-recessive parkinsonism. The parkinsonism patients also had short stature and brachydactyly. In the family and a control group from the same community, we used the DJ-1 deletion as a marker for the originally linked PARK7 region and found a significant association with body height (P = 0.005), which suggests a gene in linkage disequilibrium with DJ-1 to be implicated in short stature. Analysis of hand-bone length showed incomplete segregation of the PARK7 region with brachydactyly, such that a gene in PARK7 is unlikely to fully explain the brachydactyly. Since the bone length reduction was more pronounced in the homozygous parkinsonism patients than in their heterozygous relatives, however, the PARK7 region may contain a modifier gene for growth.

Age of Onset↗

PubMed2004

PET neuroimaging and mutations in the DJ-1 gene.

Mutations in the DJ-1 gene lead to autosomal recessive early-onset parkinsonism. We performed F-DOPA and FDG PET neuroimaging in two parkinsonism patients homozygous for DJ-1 mutations, three relatives heterozygous for a DJ-1 mutation and one non-carrier, all from the originally described kindred from The Netherlands. Their characteristics were compared to those of typical Parkinson's disease patients and healthy controls. Both parkinsonism patients had reduced F-DOPA uptake concordant with typical Parkinson's disease. In the, clinically unaffected, heterozygous relatives, F-DOPA metabolism was unremarkable, thus not suggesting a dosage effect of the DJ-1 gene.

Brain↗

PubMed2004

Familial clustering and genetic risk for dementia in a genetically isolated Dutch population.

Despite advances in elucidating the genetic epidemiology of Alzheimer's disease and frontotemporal dementia, the aetiology for most patients with dementia remains unclear. We examined the genetic epidemiology of dementia in a recent genetically isolated Dutch population founded around 1750. The series of 191 patients ascertained comprised 122 probable Alzheimer's disease patients with late onset and 17 with early onset, and 22 with possible Alzheimer's disease. It further included 10 patients with vascular dementia, nine with Lewy body dementia and six with frontotemporal dementia. All patients, except those with vascular dementia, were more closely related than healthy individuals from the same area. Clustering was strongest for patients with early-onset Alzheimer's disease or Lewy body dementia. Although 14% of late-onset Alzheimer's disease patients had evidence of autosomal dominant disease, consanguinity was found in three late-onset Alzheimer's disease patients, suggesting a recessive or polygenic model underlying the trait. We found no clustering of vascular dementia, implying a difference in genetic risk for late-onset Alzheimer's disease and vascular dementia. Mutations in known genes could not explain the occurrence of dementia, but the population attributable proportion of apolipoprotein E gene (APOE*4) was high (45%) due to a high frequency of APOE*4 carriers. Earlier identified regions on chromosomes 10 and 12, nor the effect of the alpha-2-macroglobulin (A2M) I/D polymorphism on Alzheimer's disease could be confirmed in our study. We did find evidence for association between the A2M D-allele and Lewy body dementia. Our data showed a strong familial clustering of various forms of dementia in this isolated Dutch population. A high percentage of late-onset Alzheimer's disease could be explained by APOE*4, but 55% of its origin is still unknown.

Age of Onset↗