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Biomedical subjects

H Scheffer

Publications and source records attributed to H Scheffer.

At least 19 recordsLinked to original sources
PubMed2006

The association between HTR2C polymorphisms and obesity in psychiatric patients using antipsychotics: a cross-sectional study.

The use of antipsychotics is associated with an increased risk of obesity. This consideration makes it important to search for determinants that can predict the risk for antipsychotic-induced obesity. In this cross-sectional study, we investigated whether polymorphisms in the HTR2C gene were associated with obesity (body mass index >30 kg/m2) in patients using antipsychotics. We examined polymorphisms in the promoter region of the HTR2C gene ((HTR2C:c.1-142948(GT)n, rs3813928 (-997 G/A), rs3813929 (-759 C/T), rs518147 (-697 G/C)) and an intragenic polymorphism (rs1414334:C>G). The results of the logistic regression were expressed as adjusted odds ratios (OR). In total, we included 127 patients mainly diagnosed with schizophrenia or schizoaffective disorder (89%). The results indicate that a combined genotype carrying the variant HTR2C:c.1-142948(GT)n 13 repeat allele, the common allele rs3813929 C, the variant allele rs518147 C and the variant allele rs1414334 C is significantly related to an increased risk of obesity (OR 3.71 (95% confidence interval: 1.24-11.12)).

Adult↗
PubMed2005

SMN genotypes producing less SMN protein increase susceptibility to and severity of sporadic ALS.

BACKGROUND: ALS is believed to be multifactorial in origin with modifying genes affecting its clinical expression. Childhood-onset spinal muscular atrophy (SMA) is an autosomal recessive disorder of motor neurons, caused by mutations of the survival motor neuron (SMN) gene. The SMN gene exists in two highly homologous variants: SMN1, the causative gene responsible for the production of the majority of functional SMN protein, and SMN2, responsible for the production of less protein but sufficient for modifying the SMA phenotype. OBJECTIVE: To test whether SMN genotypes are associated with susceptibility to and severity of sporadic ALS. METHODS: We performed competitive quantitative PCR analysis for both SMN1 and SMN2 genes in 242 clinically well-defined ALS patients and 175 controls. The combined determination of SMN1 and SMN2 copies also allowed for an estimation of the level of SMN for each patient (estimated SMN protein level = SMN1 copy number + 0.20 x SMN2 copy number). RESULTS: One copy of SMN1 was associated with an increased risk of developing ALS (odds ratio = 4.1, 95% CI = 1.2 to 14.2, p = 0.02) and ALS patients carried fewer SMN2 copy numbers (p < 0.001). Sixty-one percent of patients had an estimated protein SMN level < or = 2.2 vs only 36% of controls (p = 0.0000004). Multivariate Cox regression analyses showed that lower SMN2 copy numbers and lower levels of estimated SMN protein (hazard ratio = 1.3, 95% CI = 1.1 to 1.6, p = 0.03) were associated with an increased mortality rate. CONCLUSIONS: SMN genotypes producing less SMN protein increase susceptibility to and severity of ALS.

Adult↗
PubMed2005

POMT2 mutations cause alpha-dystroglycan hypoglycosylation and Walker-Warburg syndrome.

BACKGROUND: Walker-Warburg syndrome (WWS) is an autosomal recessive condition characterised by congenital muscular dystrophy, structural brain defects, and eye malformations. Typical brain abnormalities are hydrocephalus, lissencephaly, agenesis of the corpus callosum, fusion of the hemispheres, cerebellar hypoplasia, and neuronal overmigration, which causes a cobblestone cortex. Ocular abnormalities include cataract, microphthalmia, buphthalmos, and Peters anomaly. WWS patients show defective O-glycosylation of alpha-dystroglycan (alpha-DG), which plays a key role in bridging the cytoskeleton of muscle and CNS cells with extracellular matrix proteins, important for muscle integrity and neuronal migration. In 20% of the WWS patients, hypoglycosylation results from mutations in either the protein O-mannosyltransferase 1 (POMT1), fukutin, or fukutin related protein (FKRP) genes. The other genes for this highly heterogeneous disorder remain to be identified. OBJECTIVE: To look for mutations in POMT2 as a cause of WWS, as both POMT1 and POMT2 are required to achieve protein O-mannosyltransferase activity. METHODS: A candidate gene approach combined with homozygosity mapping. RESULTS: Homozygosity was found for the POMT2 locus at 14q24.3 in four of 11 consanguineous WWS families. Homozygous POMT2 mutations were present in two of these families as well as in one patient from another cohort of six WWS families. Immunohistochemistry in muscle showed severely reduced levels of glycosylated alpha-DG, which is consistent with the postulated role for POMT2 in the O-mannosylation pathway. CONCLUSIONS: A fourth causative gene for WWS was uncovered. These genes account for approximately one third of the WWS cases. Several more genes are anticipated, which are likely to play a role in glycosylation of alpha-DG.

Brain↗
PubMed2005

Seizure control and acceptance of the ketogenic diet in GLUT1 deficiency syndrome: a 2- to 5-year follow-up of 15 children enrolled prospectively.

BACKGROUND: GLUT1 deficiency syndrome is caused by impaired glucose transport into the brain resulting in an epileptic encephalopathy, developmental delay, and a complex motor disorder. A ketogenic diet provides an alternative fuel to the brain and effectively restores brain energy metabolism. METHODS: Fifteen children with GLUT1 deficiency syndrome were enrolled prospectively for a 2.0 - 5.5-year follow-up of the effectiveness of a 3 : 1 LCT ketogenic diet. Eight patients enrolled were described previously, seven patients were novel. RESULTS: Four novel heterozygous GLUT1 mutations were identified. 10/15 patients remained seizure-free on the ketogenic diet in monotherapy. In 2/15 patients seizures recurred after 2(1/2) years despite adequate ketosis, but were controlled by add-on ethosuximide. In one patient seizures were reduced without complete seizure control. No serious adverse effects occurred and parental satisfaction with the diet was good. 2/15 patients discontinued the diet. CONCLUSION: GLUT1 deficiency syndrome represents a complex childhood encephalopathy that can be treated effectively by means of a ketogenic diet. The response to the diet did not correlate to clinical, biochemical, or genetic features of the disease. In contrast to previous reports, our results indicate that epilepsy is not always completely controlled by a ketogenic diet and can recur in a subset of patients.

Adolescent↗
PubMed2004

Ectodermal dysplasia with tetramelic deficiencies and no mutation in p63: odontotrichomelic syndrome or a new entity?

The ectodermal dysplasias (ED) are a large and complex group of diseases characterized by anomalies of the ectoderm and its derivates, often associated with malformations in other organs. We report a patient with an ectodermal dysplasia affecting hair, teeth, and nails and malformations of all four extremities including absence of several rays in the hands and feet. This patient shares many similarities with odontotrichomelic syndrome, a rare ectodermal dysplasia syndrome that has so far only been described in three individuals. However, some differences exist and this patient might also represent a separate ectodermal dysplasia syndrome. p63, a gene that is mutated in a number of syndromes associated with ectodermal dysplasia and limb malformations, was considered a possible candidate gene. However, no mutation in p63 was identified.

Adult↗
PubMed2004

[Four family members with proximal myotonic myopathy].

A 41-year-old woman had a 15-year history of pain in her thighs and arms, which also became weaker, and a decrease in visual acuity. Her 35-year-old brother, their 38-year-old sister and their 64-year-old mother also had myalgia, myotonia and proximal muscle weakness, and the women also had cataracts. Additional examinations and tests led to a diagnosis of proximal myotonic myopathy (PROMM) in all four cases. Neurological and ophthalmological follow-up was provided on a yearly basis, including ECG. The clinical features of PROMM display similarities to the adult form of myotonic dystrophy (MD) but differ in the proximal localisation of the muscle weakness and the frequent occurrence of pain in the affected muscles. PROMM is an autosomal dominant hereditary multisystemic disorder with a less serious course than MD and is rarely accompanied by cognitive disorders. In most cases, a genetic defect on chromosome 3q21 is the cause of the disease. A probable diagnosis can be made on the basis of the clinical symptoms and the results of simple laboratory tests, and can be confirmed via DNA analysis. As yet, the disorder can only be treated symptomatically, preferably via a multidisciplinary approach by a neurologist, an ophthalmologist, a cardiologist and a rehabilitation specialist.

Adult↗
PubMed2004

Mevalonate kinase deficiency: Evidence for a phenotypic continuum.

Both mevalonic aciduria, characterized by psychomotor retardation, cerebellar ataxia, recurrent fever attacks, and death in early childhood, and hyper-immunoglobulin D (hyper-IgD) syndrome, with recurrent fever attacks without neurologic symptoms, are caused by a functional deficiency of mevalonate kinase. In a systematic review of known mevalonate kinase-deficient patients, the authors identified five adults with phenotypic overlap between these two syndromes, which argues for a continuous spectrum of disease. Mevalonate kinase deficiency should be considered in adult patients with fitting neurologic symptoms, with or without periodic fever attacks.

Adolescent↗
PubMed2004

Homozygous acute intermittent porphyria in a 7-year-old boy with massive excretions of porphyrins and porphyrin precursors.

A 7-year-old boy demonstrating hepatosplenomegaly, mild anaemia, mild mental retardation, yellow-brown teeth and dark red urine had excessively elevated levels of urinary delta-aminolevulinic acid, porphobilinogen and uroporphyrin. Furthermore hepta-, hexa-, penta- and copro(I)porphyrins were highly increased in urine. This pattern of porphyrin precursor and metabolite excretion is characteristic of acute intermittent porphyria. The decreased copro(III)/copro(I+III) ratio, normally not found in acute intermittent porphyria, is discussed. The porphobilinogen deaminase activity in red cells was decreased to 2-4%. Mutation analysis revealed a novel homozygous L81P mutation in exon 6 of the porphobilinogen deaminase gene. The father and mother, shown to be gene carriers of the same mutation, are asymptomatic and have normal urinary porphyrin precursor and metabolite excretion.

Child↗
PubMed2004

Autosomal recessive oculopharyngodistal myopathy: a distinct phenotypical, histological, and genetic entity.

We present a 25 year follow up of two siblings with autosomal recessive (AR) oculopharyngodistal myopathy. Remarkable in these patients, in comparison with patients with oculopharyngeal muscular dystrophy (OPMD), are the earlier age of onset, severe facial weakness, external ophthalmoplegia early in the course of the disease, and distal weakness in the limbs. Histological features included basophilic-rimmed vacuoles, but the typical OPMD intranuclear filaments were absent. These clinical and histological characteristics are comparable with those of two Japanese patients with AR oculopharyngodistal myopathy. This myopathy has usually been described as an autosomal dominant (AD) muscle disorder. It shares some clinical and histological characteristics with OPMD, but most patients with AD oculopharyngodistal myopathy are genetically different. Here we exclude an expansion of the GCG repeat or any other mutation in the coding region of the PABPN1 gene (responsible for OPMD) in patients with AR oculopharyngodistal myopathy. From this we conclude that AR oculopharyngodistal myopathy is a distinct phenotypical, histological, and genetic entity.

Adult↗
PubMed2002

Spinocerebellar ataxias in the Netherlands: prevalence and age at onset variance analysis.

BACKGROUND: International prevalence estimates of autosomal dominant cerebellar ataxias (ADCA) vary from 0.3 to 2.0 per 100,000. The prevalence of ADCA in the Netherlands is unknown. Fifteen genetic loci have been identified (SCA-1-8, SCA-10-14, SCA-16, and SCA-17) and nine of the corresponding genes have been cloned. In SCA-1, SCA2, SCA3, SCA6, SCA7, SCA-12 and SCA-17 the mutation has been shown to be an expanded CAG repeat. Previously, the length of the CAG repeat was found to account for 50 to 80% of variance in age at onset. Because of heterogeneity in encoded proteins, different pathophysiologic mechanisms leading to neurodegeneration could be involved. The relationship between CAG repeat length and age at onset would then differ accordingly. METHOD: Based on the results of SCA mutation analysis in the three DNA diagnostic laboratories that serve the entire Dutch population, the authors surveyed the number of families and affected individuals per SCA gene, as well as individual repeat length and age at onset. Regression analysis was applied to study the relationship between CAG repeat length and age at onset per SCA gene. The slopes of the different regression curves were compared. RESULTS: On November 1, 2000, mutations were found in 145 ADCA families and 391 affected individuals were identified. The authors extrapolated a minimal prevalence of 3.0 per 100,000 (range 2.8 to 3.8/100,000). SCA3 was the most frequent mutation. CAG repeat length contributed to 52 to 76% of age at onset variance. Regression curve slopes for SCA-1, SCA2, SCA3, and SCA7 did not differ significantly. CONCLUSIONS: The estimated minimal prevalence of ADCA in the Netherlands is 3.0 per 100,000 inhabitants. Except for SCA6, the relationship between age at onset and CAG repeat expansion does not differ significantly between SCA-1, SCA2, SCA3, and SCA7 patient groups in our population, indicating that these SCA subtypes share similar mechanisms of polyglutamine-induced neurotoxicity, despite heterogeneity in gene products.

Adult↗
PubMed2001

[From gene to disease; 'survival' motor neuron protein and hereditary proximal spinal muscle atrophy].

The majority of patients with hereditary proximal spinal muscular atrophy (SMA) have a homozygous deletion of the survival motor neuron gene (SMN1). The number of SMN2 gene copies modifies the phenotype, which ranges from a lethal infantile disorder to an adult-onset disease causing mild impairment and disability. The SMN protein plays a role in an apparently essential cell metabolism process, the splicing of pre-mRNA in the spliceosomes. Why SMN1 deletions are only clinically expressed in motor neuron cells and not in other cell types is still unknown. DNA analysis, prenatal diagnosis and carrier testing as means of diagnosing SMA are all routinely available in the Netherlands and are currently performed at the DNA laboratory of the University of Groningen.

Adult↗
PubMed2001

[From gene to disease; retinoblastoma and the RB1 gene].

Retinoblastoma is caused by mutations in the RB1 gene. The penetrance is 95%, as in approximately 5% of the mutation carriers, no second somatic mutation occurs in one of their retina cells during embryonic development. Molecular diagnosis is performed by a complete scanning of the RB1 coding sequence which includes flanking intronic sequences. Approximately 85% of pathogenic mutations can be identified.

Child↗
PubMed2001

[From gene to disease; from defective chloride ion transport to cystic fibrosis].

Cystic fibrosis is an autosomal recessive disorder affecting the lungs, pancreas, intestines, sweat ducts and liver, due to an abnormal salt transport across the apical border of epithelial cells. Mutations in the CF underlying gene, the cystic fibrosis transmembrane conductance regulator (CFTR) gene, result in most cell types in an misprocessing so that little of the protein reaches the membranes. In case of clinical suspicion and/or doubtful sweat test results, mutation analysis can support the diagnosis of CF. Also carrier detection is offered.

Adult↗
PubMed2001

Homozygous deletion of the survival motor neuron 2 gene is a prognostic factor in sporadic ALS.

BACKGROUND: Spinal muscular atrophy (SMA) results from mutations of the survival motor neuron (SMN) gene on chromosome 5. The SMN gene exists in two highly homologous copies, telomeric (SMN1) and centromeric (SMN2). SMA is caused by mutations in SMN1 but not SMN2. The clinical phenotype of SMA appears to be related to the expression of SMN2. Patients suffering from the milder forms of SMA carry more copies of the SMN2 gene compared with patients with more severe SMA. It is suggested that the SMN2 gene is translated into an at least partially functional protein that protects against loss of motor neurons. OBJECTIVE: To investigate whether genetic mechanisms implicated in motor neuron death in SMA have a role in ALS. METHODS: The presence of deletions of exons 7 and 8 of SMN1 and SMN2 was determined in 110 patients with sporadic ALS and compared with 100 unaffected controls. RESULTS: The presence of a homozygous SMN2 deletion was overrepresented in patients with ALS compared with controls (16% versus 4%; OR, 4.4; 95% CI, 1.4 to 13.5). Patients with a homozygous SMN2 deletion had a shorter median time of survival (p < 0.009). Furthermore, multivariate regression analysis showed that the presence of an SMN2 deletion was independently associated with survival time (p < 0.02). No homozygous deletions in SMN1 were found. Carrier status of SMA appeared to be equally present in patients and controls (1 in 20). CONCLUSION: These results indicate that, similar to SMA, the SMN2 gene can act as a prognostic factor and may therefore be a phenotypic modifier in sporadic ALS. Increasing the expression of the SMN2 gene may provide a strategy for treatment of motor neuron disease.

Age of Onset↗
PubMed2001

[Quality control of DNA testing in hereditary diseases].

The laboratories performing diagnostic studies regarding hereditary diseases and the specialists providing hereditary counselling are housed in clinical genetic centres. The laboratories are subject to the Special Medical Performances Act and have had licenses from the Ministry. The DNA diagnostic laboratories united in the National Committee on DNA Diagnostics, engaged among other things in quality control. The large number of tests requested and the dramatic consequences for the patient and his relatives necessitate high quality standards. The laboratories made a division of labour for analysis of most disorders, in order to acquire and maintain expertise in spite of rarity of most hereditary diseases. For adequate handling of requests for DNA diagnostic tests, it is important that the patient material be sent directly to the laboratory specialized in the disorders in question, for the request form to be filled out completely and for the patient data to be stated on the blood tube. A regularly updated review of the DNA diagnostics in the Netherlands can be found on the website: http://www.unimaas.nl/ approximately LOD/lod.htm. This list indications per centre and information such as required material and maximal results deadlines.

Genetic Diseases, Inborn↗
PubMed2001

Detection of myocardial viability based on measurement of sodium content: A (23)Na-NMR study.

MRI of total sodium (Na) content may allow assessment of myocardial viability, but information on Na content in normal myocardium, necrotic/scar tissue, and stunned or hibernating myocardium is lacking. Thus, the aims of the study were to: 1) quantify the temporal changes in myocardial Na content post-myocardial infarction (MI) in a rat model (Protocol 1); 2) compare Na in normally perfused, hibernating, and stunned canine myocardium (Protocol 2); and 3) determine whether, in buffer-perfused rat hearts, infarct scar can be differentiated from intact myocardium by (23)Na-MRI (Protocol 3). In Protocol 1, rats were subjected to LAD ligation. Infarct/scar tissue was excised at control and 1, 3, 7, 28, 56, and 128 days post-MI (N = 6-8 each), Na content was determined by (23)Na-NMR spectroscopy (MRS) and ion chromatography. Na content was persistently increased at all time points post-MI averaging 306*-160*% of control values (*P < 0.0083 vs. control). In Protocol 2, (23)Na-MRS of control (baseline), stunned and hibernating samples revealed no difference in Na. In Protocol 3, (23)Na-MRI revealed a mean increase in signal intensity, to 142 +/- 6% of control values, in scar tissue. A threshold of 2 standard deviations of the image intensity allowed determination of infarct size, correlating with histologically determined infarct size (r = 0.91, P < 0.0001).

Animals↗