Cancer spectrum and frequency among children with Noonan, Costello, and cardio-facio-cutaneous syndromes.

BACKGROUND: Somatic mutations affecting components of the Ras-MAPK pathway are a common feature of cancer, whereas germline Ras pathway mutations cause developmental disorders including Noonan, Costello, and cardio-facio-cutaneous syndromes. These 'RASopathies' also represent cancer-prone syndromes, but the quantitative cancer risks remain unknown. METHODS: We investigated the occurrence of childhood cancer including benign and malignant tumours of the central nervous system in a group of 735 individuals with germline mutations in Ras signalling pathway genes by matching their information with the German Childhood Cancer Registry. RESULTS: We observed 12 cases of cancer in the entire RASopathy cohort vs 1.12 expected (based on German population-based incidence rates). This corresponds to a 10.5-fold increased risk of all childhood cancers combined (standardised incidence ratio (SIR)=10.5, 95% confidence interval=5.4-18.3). The specific cancers included juvenile myelomonocytic leukaemia=4; brain tumour=3; acute lymphoblastic leukaemia=2; rhabdomyosarcoma=2; and neuroblastoma=1. The childhood cancer SIR in Noonan syndrome patients was 8.1, whereas that for Costello syndrome patients was 42.4. CONCLUSIONS: These data comprise the first quantitative evidence documenting that the germline mutations in Ras signalling pathway genes are associated with increased risks of both childhood leukaemia and solid tumours.

Variegate porphyria in a 46-year-old patient taking sibutramine for weight loss.

The acute hepatic porphyrias can cause life-threatening attacks of neurovisceral symptoms that mimic other acute medical conditions. Variegate porphyria caused by mutations in the protoporphyrinogen oxidase (PPOX) gene is a latent disorder characterized by exacerbations induced by fasting, alcohol consumption or certain drugs. We describe the case of a 46-year-old female patient presenting with a first episode of symptomatic porphyria after 10 d of sibutramine treatment for weight loss. Genetic analysis showed a heterozygous R168H hot spot mutation in the PPOX gene. A putative effect of sibutramine on the hepatic haem biosynthetic pathway and reduced food intake have likely caused this exacerbation of a porphyria attack. Although this may be the first case report of this kind, the risk of acute porphyria should be considered in patients using pharmacotherapy for obesity.

Presentación tardía de una deficiencia de carbamilfosfato sintetasa 1 en un niño de 6 años / Late-onset presentation of carbamoyl phosphate synthetase 1 deficiency in a 6-year-old boy

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Plexin B3 is genetically associated with verbal performance and white matter volume in human brain.

The presence of genetic influences on cognitive performance and brain volume is well established. However, specific genetic determinants of the variance of these quantitative traits are not yet known. Plexins act as receptors for semaphorins and are implicated in axon guidance, which is a key process in brain development. We have previously shown that plexin B3 is a highly potent stimulator of neurite outgrowth, which makes its gene PLXNB3 an intriguing candidate gene for traits related to human brain development and cerebral connectivity. We identified several polymorphisms in PLXNB3 predicting changes of amino acids (V598I, E1156D and V1596E) conserved at the corresponding positions of the orthologs in mouse and chimpanzee. PLXNB3 was genotyped in 303 healthy volunteers and 42 male patients with schizophrenia. Cognitive performance was measured with the vocabulary test (Wortschatztest (WST)), a method to estimate roughly general intelligence (g). Brain morphology was characterized by magnetic resonance imaging. Compared to subjects not carrying the modern, human-specific haplotype A, carriers of A scored higher in vocabulary test (WST) irrespective of diagnosis (P=0.0004). This effect could be observed in three independent groups (healthy males: P=0.048; schizophrenic males: P=0.034 and healthy females: P=0.037). Additionally, the haplotype A was associated with increased volume of brain white matter that in turn correlated with performance in the vocabulary test. These findings suggest that plexin B3 may influence cognitive performance, and the development of white matter in vivo in a way similar to its known stimulating effect on neurite outgrowth in vitro. These novel observations warrant further replication in independent samples.

Indication of circadian oscillations in the rat pancreas.

The central circadian oscillator of the suprachiasmatic nucleus controls diurnal rhythmicity of the body with light as its dominant zeitgeber. Recently, peripheral oscillators have been detected in liver and heart, which follow as yet unidentified cues. In this study real-time reverse transcription-polymerase chain reaction (RT-PCR) was used in analysis of the expression of the major clock genes Per1, Per2, Bmal1, Cry1, Tim (timeless) and Clock, as well as of the output genes Dbp and Rev-erbalpha in the pancreatic tissue of rats. The results presented here indicate a robust circadian expression of clock genes (e.g. Per1 and Bmal1) and the probable existence of a peripheral oscillator in the pancreas. Whether this oscillator regulates the diverse functions of the islets of Langerhans remains to be elucidated.

CSF-tau, CSF-Abeta1-42, ApoE-genotype and clinical parameters in the diagnosis of Alzheimer's disease: combination of CSF-tau and MMSE yields highest sensitivity and specificity.

This study evaluated the sensitivity and specificity of the cerebrospinal fluid (CSF) levels of tau-protein, amyloid-beta-peptide 1-42 (Abeta1-42), ApoE-genotype and the degree of cognitive decline as diagnostic markers for Alzheimer's disease (AD). Data was obtained from 105 AD patients and 68 controls. Median CSF-tau levels were increased (512 pg/ml vs. 145 pg/ml, p<0.001) and Abeta1-42-levels were decreased (238.5 pg/ml vs. 310 pg/ml, p<0.001) in AD patients compared to controls. A weak correlation was found between CSF-Abeta1-42 and MMSE score (r=.245). Within all subjects, a correlation of CSF-Abeta1-42 (r=-.337) and CSF-tau (r=.384) with age was found. The combination of CSF-tau levels and MMSE revealed the highest sensitivity (92%) and specificity (87%). In summary, CSF-tau was a useful biological marker to discriminate AD from normal aging, neurological and psychiatric disorders. CSF-Abeta1-42 showed no additional benefit in discriminating patients from controls but might be useful for tracking the severity of the disease.

Association of late-onset Alzheimer disease with a genotype of PLAU, the gene encoding urokinase-type plasminogen activator on chromosome 10q22.2.

Urokinase-type plasminogen activator (uPA) converts plasminogen to plasmin. Plasmin is involved in processing of amyloid precursor protein and degrades secreted and aggregated amyloid-beta, a hallmark of Alzheimer disease (AD). PLAU, the gene encoding uPA, maps to chromosome 10q22.2 between two regions showing linkage to late-onset AD (LOAD). We genotyped a frequent C/T single nucleotide polymorphism in codon 141 of PLAU (P141L) in 347 patients with LOAD and 291 control subjects. LOAD was associated with homozygous C/C PLAU genotype in the whole sample (chi2=15.7, P=0.00039, df 2), as well as in all sub-samples stratified by gender or APOE epsilon4 carrier status (chi2> or = 6.84, P< or =0.033, df 2). Odds ratio for LOAD due to homozygosity C/C was 1.89 (95% confidence interval 1.37-2.61). PLAU is a promising new candidate gene for LOAD, with allele C (P141) being a recessive risk allele or allele T (L141) conferring protection.

The future of genetic association studies in Alzheimer disease.

Molecular genetics significantly contributed to the current concepts of the etiology of Alzheimer disease (AD). The genetic association between APOE epsilon4 and both sporadic and familial late-onset AD (LOAD) was discovered almost one decade ago. Soon after this breakthrough it became clear that there should exist additional risk alleles of other genes in order to fully explain the proportion of AD attributable to genetic factors. However, up to now none of the numerous studies involving more than 100 candidate genes revealed convincing evidence for any predisposing risk alleles in genes other than APOE. This review briefly discusses possible reasons for this lack of success and proposes criteria for a more efficient selection of positional and functional candidate genes for LOAD.

Ethanol and gene expression in brain.

This article represents the proceedings of a symposium at the 2000 ISBRA Meeting in Yokohama, Japan. The chairs were Izuru Matusmoto and Peter A. Wilce. The presentations were (1) GABA receptor subunit expression in the human alcoholic brain, by Tracey Buckley and Peter Dodd; (2) NMDAR gene expression during ethanol addiction, by Jorg Puzke, Rainer Spanagel, Walther Zieglgansberger, and Gerald Wolf; (3) Differentially expressed gene in the nucleus accumbens from ethanol-administered rat, by Shuangying Leng; (4) Expression of a novel gene in the alcoholic brain, by Peter A. Wilce; and (5) Investigations of haplotypes of the dopamine D2-receptor gene in alcoholics, by Hans Rommelspacher, Ulrich Finckh, and Lutz G. Schmidt.

Non-replication of association between cathepsin D genotype and late onset Alzheimer disease.

In two recent studies from Germany, a strong association was found between the allelic variant T of the amino acid substitution encoding polymorphism 224 C/T (A38V) in exon 2 of the cathepsin D gene (CTSD) and late onset Alzheimer disease (AD). Other studies from Europe and the USA revealed ambiguous results. Therefore, we performed an independent association study on CTSD and AD in a sample of 324 Caucasian patients from Germany, Switzerland, and Italy with late onset AD, and 302 non-demented controls. We could not confirm an association between CTSD genotype and AD, although there was a slight but not significant increase in frequency of the T allele and T carrier status in AD. Post hoc data analyses suggested that there might be a stronger effect of CTSD genotype on AD risk in males, and an interaction between CTSD and APOE genotypes in males but not females.

Molecular genetic alterations on chromosomes 11 and 22 in ependymomas.

Ependymomas arise from the ependymal cells at different locations throughout the brain and spinal cord. These tumors have a broad age distribution with a range from less than 1 year to more than 80 years. In some intramedullary spinal ependymomas, mutations in the neurofibromatosis 2 (NF2) gene and loss of heterozygosity (LOH) on chromosome arm 22q have been described. Cytogenetic studies have also identified alterations involving chromosome arm 11q, including rearrangements at 11q13, in ependymomas. We analyzed 21 intramedullary spinal, 14 ventricular, 11 filum terminale and 6 intracerebral ependymomas for mutations in the MEN1 gene, which is located at 11q13, and mutations in the NF2 gene, which is located at 22q12, as well as for LOH on 11q and 22q. NF2 mutations were found in 6 tumors, all of which were intramedullary spinal and all of which displayed LOH 22q. Allelic loss on 22q was found in 20 cases and was significantly more frequent in intramedullary spinal ependymomas than in tumors in other locations. LOH 11q was found in 7 patients and exhibited a highly significant inverse association with LOH 22q (p<0.001). A hemizygous MEN1 mutation was identified in 3 tumors, all of which were recurrences from the same patient. Interestingly, the initial tumor corresponded to WHO grade II and displayed LOH 11q but not yet a MEN1 mutation. In 2 subsequent recurrences, the tumor had progressed to anaplastic ependymoma (WHO grade III) and exhibited a nonsense mutation in exon 10 of MEN1 (W471X) in conjunction with LOH 11q. This suggests that loss of wild-type MEN1 may be involved in the malignant progression of a subset of ependymomas. To conclude, our findings provide evidence for different genetic pathways involved in ependymoma formation and progression, which may allow to define genetically and clinically distinct tumor entities.

Genetic association of a cystatin C gene polymorphism with late-onset Alzheimer disease.

OBJECTIVE: To determine whether the cystatin C gene (CST3) is genetically associated with late-onset Alzheimer disease (AD). DESIGN: A case-control study with 2 independent study populations of patients with AD and age-matched, cognitively normal control subjects. SETTING: The Alzheimer's Disease Research Unit at the University Hospital Hamburg-Eppendorf, Hamburg, Germany, for the initial study (n = 260). For the independent multicenter study (n = 647), an international consortium that included the Massachusetts Alzheimer's Disease Research Center at the Massachusetts General Hospital, Boston; the Scientific Institute for Research and Patient Care, Brescia, Italy; and Alzheimer's research units at the Universities of Basel and Zurich, Switzerland, and Bonn, Goettingen, and Hamburg, Germany. PARTICIPANTS: Five hundred seventeen patients with AD and 390 control subjects. MEASURES: Molecular testing of the KspI polymorphisms in the 5' flanking region and exon 1 of CST3 and the apolipoprotein E (APOE) genotype. Mini-Mental State Examination scores for both patients with AD and control subjects. RESULTS: Homozygosity for haplotype B of CST3 was significantly associated with late-onset AD in both study populations, with an odds ratio of 3.8 (95% confidence interval, 1.56-9.25) in the combined data set; heterozygosity was not associated with an increased risk. The odds ratios for CST3 B/B increased from 2.6 in those younger than 75 years to 8.8 for those aged 75 years and older. The association of CST3 B/B with AD was independent of APOE epsilon4; both genotypes independently reduced disease-free survival. CONCLUSIONS: CST3 is a susceptibility gene for late-onset AD, especially in patients aged 75 years and older. To our knowledge, CST3 B is the first autosomal recessive risk allele in late-onset AD.

Spectrum and detection rate of L1CAM mutations in isolated and familial cases with clinically suspected L1-disease.

Mutations in L1CAM, the gene encoding the L1 neuronal cell adhesion molecule, lead to an X-linked trait characterized by one or more of the symptoms of hydrocephalus, adducted thumbs, agenesis or hypoplasia of corpus callosum, spastic paraplegia, and mental retardation (L1-disease). We screened 153 cases with prenatally or clinically suspected X-chromosomal hydrocephalus for L1CAM mutations by SSCP analysis of the 28 coding exons and regulatory elements in the 5'-untranslated region of the gene. Forty-six pathogenic mutations were found (30.1% detection rate), the majority consisting of nonsense, frameshift, and splice site mutations. In eight cases, segregation analysis disclosed recent de novo mutations. Statistical analysis of the data indicates a significant effect on mutation detection rate of (i) family history, (ii) number of L1-disease typical clinical findings, and (iii) presence or absence of signs not typically associated with L1CAM-disease. Whereas mutation detection rate was 74.2% for patients with at least two additional cases in the family, only 16 mutations were found in the 102 cases with negative family history (15.7% detection rate). Our data suggest a higher than previously assumed contribution of L1CAM mutations in the pathogenesis of the heterogeneous group of congenital hydrocephalus.

Variable expression of familial Alzheimer disease associated with presenilin 2 mutation M239I.

In a family with autopsy-confirmed Alzheimer disease, the authors found a mutation in the presenilin 2 (PS2) gene (PSEN2) that predicts a methionine-to-isoleucine change at PS2 residue 239 (M239I), at which a change to valine was known in another family. Phenotypic expression of M239I was highly variable, with disease onset between age 44 and 58 years, and two nonaffected mutation carriers at age 58 and 68 years. The data showed no influence of APOE but were compatible with other possible genetic modifiers of the phenotype or penetrance of M239I.

High prevalence of pathogenic mutations in patients with early-onset dementia detected by sequence analyses of four different genes.

Clinical differential diagnosis of early-onset dementia (EOD) includes familial Alzheimer disease (FAD) and hereditary prion disease. In both disease entities, postmortem brain histopathological examination is essential for unambiguous diagnosis. Mutations in the genes encoding the presenilins (PS1 and PS2) and amyloid precursor protein (APP) are associated with FAD, whereas mutations in the prion protein (PrP) gene are associated with prion disease. To investigate the proportion of EOD attributable to known genes, we prospectively (i.e., antemortem) screened these four genes for mutations by sequencing genomic PCR products from patients with EOD before age 60 years. Family history for dementia was positive (PFH) in 16 patients, negative (NFH) in 17 patients, and unknown (UFH) in 3 patients. In 12 patients, we found five novel mutations (in PS1, F105L; in PS2, T122P and M239I; and in PrP, Q160X and T188K) and five previously reported mutations (in APP, in three patients who were most likely unrelated, V717I; in PS1, A79V and M139V; and in PrP, P102L and T183A) that are all considered to be disease causing. Of these 12 patients, 9 had PFH. This indicates a detection rate of 56% (9/16) in patients with PFH. We found two mutations (APP V717I) in two of the three UFH patients, and only one mutation (PrP T188K) in 1 of the 17 patients with NFH. We conclude that because of the lack of specific antemortem diagnostic markers for FAD and hereditary prion disease, all four genes should be included in a molecular diagnostic program in patients with EOD who had PFH.

High frequency of mutations in four different disease genes in early-onset dementia.

Heterozygous mutations in the genes for amyloid precursor protein (APP), the presenilins (PS1, PS2), prion protein (PrP), neuroserpin, and tau are associated with early-onset dementia (EOD) with or without neurological signs in the early disease stage. To investigate the proportion of EOD without early neurological signs attributable to known genes we prospectively (i.e., ante mortem) screened these six genes for mutations in 36 patients with EOD before age 60. Family history for dementia was positive (PFH) in 16, negative (NFH) in 17, and unknown (UFH) in 3 patients. In 12 patients, we found 5 novel mutations (PS1: F105L; PS2: T122P, M239I; PrP: Q160X, T188K) and 5 previously reported mutations (APP: in three most likely unrelated patients V717I; PS1: A79V, M139V; PrP: P102L, T183A) that all are considered disease causing. Of these 12 patients, 9 had PFH. This indicates a detection rate of 56% (9/16) in patients with PFH. We found 2 mutations (APP V717I) in 2 of the 3 the UFH-patients, and only 1 mutation (PrP T188K) in 1 of the 17 patients with NFH. No mutation was found in tau and neuroserpin genes. To date, three patients died and FAD, predicted by PS mutations in two patients, and prion disease, predicted by a PrP mutation in the third one, were histopathologically confirmed at autopsy. Up to now, mutation findings may be the most specific biomarkers for an ante mortem diagnosis of FAD or hereditary prion disease.