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PubMedDate not supplied

Prenatal diagnosis in Rett syndrome.

BACKGROUND/AIM: Rett syndrome (RTT) is an X-linked neurodevelopmental dominant disorder that affects almost exclusively girls. The disease is mainly sporadic, caused by de novo mutations at MECP2 gene (Xq28), but a low percentage of familial cases have been reported. We present the results of RTT prenatal diagnosis in three families and discuss the usefulness of such analyses in diseases caused mainly by de novo mutations. METHODS: For adult individuals, DNA was extracted from peripheral lymphocytes; for fetus analysis it was obtained from cultured amniotic fluid or from chorionic biopsy specimens. Mutation detection at MECP2 gene was first carried out in the patients by SSCP/HD analysis and subsequent sequencing. Family studies and prenatal diagnoses were done by direct analysis of previously characterized patients' mutations using SSCP/HD or restriction analysis. RESULTS: Heterozygous mutations identified in the 3 patients were: 1061del96bp, 473C-->T, and 763C-->T, respectively. Mutations were not present in the mothers' DNAs obtained from peripheral lymphocytes. None of the 3 fetuses analyzed carried the mutation of the affected sister. CONCLUSIONS: Recurrence within RTT families can be due to asymptomatic nonpenetrant carrier mothers or to parental germinal mosaicism for the MECP2 mutation. Since germline mosaicism can neither be predicted nor detected, families with 1 affected patient whose RTT-causing mutation has been previously identified can benefit from prenatal diagnosis which contributes to a decrease in the recurrence risk in a new pregnancy comparable to that of the normal population.

Chromosomal Proteins, Non-Histone↗
PubMed2006

Mutation analysis in hereditary haemorrhagic telangiectasia in Germany reveals 11 novel ENG and 12 novel ACVRL1/ALK1 mutations.

Hereditary haemorrhagic telangiectasia (HHT) is an autosomal-dominant disease characterized by recurrent epistaxis, mucocutaneous telangiectasias and visceral arteriovenous malformations. Mutations in endoglin (ENG) and activin A receptor type II-like kinase 1 (ACVRL1 or ALK1) have been found in patients with HHT. We have screened a total of 51 unselected German index cases with the suspected diagnosis of HHT. We identified 30 different mutations in 32 cases (62.7%) by direct sequencing. Among these mutations, 11 of 13 ENG mutations and 12 of 17 ACVRL1 mutations were not previously reported in the literature. Two of the ACVRL1 mutations were each shared by two families. An analysis of the genotype-phenotype correlation is consistent with a more common frequency of pulmonary arteriovenous malformations in patients with ENG mutations than in patients with ACVRL1 mutations in our collective.

Activin Receptors, Type II↗
PubMed2004

Germline mutations of the paired-like homeobox 2B (PHOX2B) gene in neuroblastoma.

Neuroblastoma (NB) is a frequent pediatric tumor for which recurrent somatic rearrangements are known. Germline mutations of predisposing gene(s) are suspected on the basis of rare familial cases and the association of NB with other genetically determined congenital malformations of neural crest-derived cells--namely, Hirschsprung disease (HSCR) and/or congenital central hypoventilation syndrome (CCHS). We recently identified the paired-like homeobox 2B (PHOX2B) gene as the major disease-causing gene in isolated and syndromic CCHS, which prompted us to regard it as a candidate gene in NB. Here, we report on germline mutations of PHOX2B in both a familial case of NB and a patient with the HSCR-NB association. PHOX2B, therefore, stands as the first gene for which germline mutations predispose to NB.

Base Sequence↗
PubMed2005

A transforming growth factor-beta receptor-interacting protein frequently mutated in human ovarian cancer.

Ovarian carcinomas, particularly recurrent forms, are frequently resistant to transforming growth factor-beta (TGF-beta)-mediated growth inhibition. However, mutations in the TGF-beta receptor I and receptor II (TbetaR-I and TbetaR-II) genes have only been reported in a minority of ovarian carcinomas, suggesting that alterations in TGF-beta-signaling components may play an important role in the loss of TGF-beta responsiveness. Using laser-capture microdissection and nested reverse-transcription-PCR, we found that km23, which interacts with the TGF-beta receptor complex, is altered at a high frequency in human ovarian cancer patients. A novel form of km23, missing exon 3 (Deltaexon3-km23), was found in 2 of 19 tumor tissues from patients with ovarian cancer. In addition to this alteration, a stop codon mutation (TAA --> CAC) was detected in two patients. This alteration results in an elongated protein, encoding 107-amino-acid residues (Delta107km23), instead of the wild-type 96-amino-acid form of km23. Furthermore, five missense mutations (T38I, S55G, T56S, I89V, and V90A) were detected in four patients, providing a total alteration rate of 42.1% (8 of 19 cases) in ovarian cancer. No km23 alterations were detected in 15 normal tissues. Such a high alteration rate in ovarian cancer suggests that km23 may play an important role in either TGF-beta resistance or tumor progression in this disease. In keeping with these findings, the functional studies described herein indicate that both the Deltaexon3-km23 and S55G/I89V-km23 mutants displayed a disruption in binding to the dynein intermediate chain in vivo, suggesting a defect in cargo recruitment to the dynein motor complex. In addition, the Deltaexon3-km23 resulted in an inhibition of TGF-beta-dependent transcriptional activation of both the p3TP-lux and activin responsive element reporters. Collectively, our results suggest that km23 alterations found in ovarian cancer patients result in altered dynein motor complex formation and/or aberrant transcriptional regulation by TGF-beta.

Aged↗
PubMed1999

Recurrence of Marfan syndrome as a result of parental germ-line mosaicism for an FBN1 mutation.

Mutations in the FBN1 gene cause Marfan syndrome (MFS), a dominantly inherited connective tissue disease. Almost all the identified FBN1mutations have been family specific, and the rate of new mutations is high. We report here a de novo FBN1mutation that was identified in two sisters with MFS born to clinically unaffected parents. The paternity and maternity were unequivocally confirmed by genotyping. Although one of the parents had to be an obligatory carrier for the mutation, we could not detect the mutation in the leukocyte DNA of either parent. To identify which parent was a mosaic for the mutation we analyzed several tissues from both parents, with a quantitative and sensitive solid-phase minisequencing method. The mutation was not, however, detectable in any of the analyzed tissues. Although the mutation could not be identified in a sperm sample from the father or in samples of multiple tissue from the mother, we concluded that the mother was the likely mosaic parent and that the mutation must have occurred during the early development of her germ-line cells. Mosaicism confined to germ-line cells has rarely been reported, and this report of mosaicism for the FBN1 mutation in MFS represents an important case, in light of the evaluation of the recurrence risk in genetic counseling of families with MFS.

Adult↗
PubMed2006

Neutrophil elastase and granulocyte colony-stimulating factor receptor mutation analyses and leukemia evolution in severe congenital neutropenia patients belonging to the original Kostmann family in northern Sweden.

BACKGROUND AND OBJECTIVES: Severe congenital neutropenia (SCN) or Kostmann syndrome was originally reported to be an autosomal recessive disease of neutrophil production causing recurrent, life-threatening infections. Mutations in the neutrophil elastase gene (ELA-2) have previously been identified in patients with sporadic or autosomal dominant SCN. DESIGN AND METHODS: We studied 14 individuals (four patients with SCN and ten close relatives) belonging to the original Kostmann family in northern Sweden for mutations in the ELA-2 and the granulocyte colony-stimulating factor (G-CSF) receptor genes. RESULTS: One patient belonging to the original Kostmann family harbored a novel heterozygous ELA-2 mutation (g.2310T-->A;Leu92His) that was not inherited from her parents. The mutation was identified in DNA isolated from both whole blood and skin fibroblasts, suggesting a sporadic de novo mutation. As a young adult this patient sequentially acquired two mutations in the gene for the G-CSF receptor (G-CSFR) and therefore recently received a hematopoietic stem cell transplant, due to the risk of evolution to leukemia. Moreover, another patient developed acute leukemia and was treated with transplantation. No pathogenic ELA-2 or G-CSFR gene mutations were found in this patient or the other two patients, nor in any healthy relative. INTERPRETATION AND CONCLUSIONS: Our data are the first to document leukemia evolution and G-CSFR gene mutations in the original Kostmann kindred. In addition, our findings indicate that ELA-2 mutations are not the primary cause of SCN in the Swedish Kostmann family.

Adult↗
PubMed1994

Population genetics of phenylketonuria.

Phenylketonuria (PKU) is an autosomal recessive disorder caused by a large number of mutations at the phenylalanine hydroxylase (PAH) locus, most of which are strongly associated with specific RFLP or VNTR haplotypes. One of the major questions remaining in PKU research is why this apparently maladaptive disorder has been maintained at a frequency of approximately 1 in 10,000 among Caucasians. A growing number of studies have provided evidence that both the relatively high frequency of PKU and the strong mutation/haplotype associations might reflect the existence of multiple founding populations for PKU. Examples of putative founding populations for PKU in both Europe and Asia will be presented. Some PAH mutations are associated with multiple haplotypes, suggesting recurrence. Evidence for and against recurrence as the mechanism responsible for the association of the R408W mutation with RFLP haplotypes 1 and 2 will be discussed.

Asia↗
PubMed2002

Identification of FBN1 gene mutations in patients with ectopia lentis and marfanoid habitus.

BACKGROUND: Marfan syndrome (MFS), inherited as an autosomal dominant trait, typically affects the cardiovascular, skeletal, and ocular systems. Ectopia lentis (EL) is a clinical manifestation of MFS, with stretching or disruption of the lenticular zonular filaments, leading to displacement of the lenses. EL, with or without minor skeletal changes, exists as an independent autosomal dominant phenotype linked to the same FBN1 locus. METHODS: A consecutive series of 11 patients, affected predominantly by EL, was analysed for FBN1 mutations using PCR, SSCA, and sequencing. RESULTS: Six mutations were identified, of which three are novel and one is recurrent in two patients, thus establishing a mutation incidence in this group of 7/11 (63%). CONCLUSION: The FBN1 variants reported are clustered in the first 15 exons of the gene, while FBN1 mutations reported in the literature are distributed throughout the entire length of the gene. A different type of FBN1 mutation presents in this group of patients, compared with MFS, with arginine to cysteine substitutions appearing frequently.

Adult↗
PubMed2007

Ornithine transcarbamylase deficiency presenting as encephalopathy during adulthood following bariatric surgery.

BACKGROUND: Neurological complications following bariatric surgery are rare. Whereas nutritional deficiencies are the most common cause of neurological symptoms, the unmasking of previously subclinical metabolic disorders can also lead to significant morbidity. OBJECTIVE: To characterize the clinical presentation, serum biochemical fluctuations, and functional enzymatic analysis of a case of functional ornithine transcarbamylase deficiency unmasked by a dietary change following bariatric surgery. DESIGN: Case report. SETTING: Tertiary referral center, hospital (inpatient) setting. PATIENT: A 29-year-old woman who presented with intermittent encephalopathy associated with recurrent hyperammonemia. INTERVENTIONS: Clinical, biochemical, and mutational studies. RESULTS: The pattern of intermittent hyperammonemia and encephalopathy following oral and parenteral nutrition suggested a urea cycle abnormality. Functional enzymatic assay results showed markedly reduced ornithine transcarbamylase activity in the absence of known coding mutations. CONCLUSION: Previously asymptomatic ornithine transcarbamylase deficiency should be suspected in adult patients who develop recurrent hyperammonemia and encephalopathy following bariatric surgery.

Adult↗
PubMed1986

Origin of new mutations in Duchenne muscular dystrophy.

Nine unrelated pedigrees in which Duchenne muscular dystrophy (DMD) was not present in more than one sibship were studied, using 6 DNA polymorphisms closely linked to the DMD gene. The reconstruction of grandparental haplotypes indicates the occurrence of at least three new mutations, two in grandpaternal chromosomes and one in a grandmaternal chromosome. Two additional (but less well documented) new mutations might have occurred respectively in a grandfather's and in a grandmother's chromosome, the latter being represented by a deletion mutation. The new mutations detected in this study therefore add to a total of either three or five out of nine apparently independent mutations present in pedigrees without recurrence of the disorder.

DNA↗
PubMed2006

[Hereditary form of thrombotic thrombocytopenic purpura].

BACKGROUND: Thrombotic thrombocytopenic purpura is characterized by microvascular platelet clumping resulting in thrombocytopenia, microangiopathic hemolysis, neurological abnormality, and renal dysfunction. Similar manifestations also occur in patients with the hemolytic uremic syndrome or other types of disorders. Recent studies demonstrate that severe deficiency of the von Willebrand factor cleaving metalloprotease, ADAMTS 13, causes thrombotic thrombocytopenic purpura. Aim of our study was to characterize gene defects causing inherited type of disease. METHODS AND RESULTS: We investigated nine patients with recurrent type of disease with familiar origin and twelve relatives. Samples were taken in a remission of disease. We measured activity of ADAMTS13 (vWF-CP) with modified method of the quantitative immunoblotting of degraded vWF multimers. Mutation screening was carried out by sequencing all 29 exons and flanking intron regions of the ADAMTS13 gene. Five distinct mutations were found. Three of them are novel. CONCLUSIONS: Mutation analysis of the ADAMTS 13 gene brought interesting results in eight patients. We found a one single base frameshift insertion, 4143insA in 8 of 9 unrelated individuals. This investigation represents an advantage in the differential diagnosis of disease since the thrombotic thrombocytopenic purpura phenotype in childhood can be variable and rapid detection of mutation is helpful for the recurrence prevention.

ADAM Proteins↗
PubMed2004

Outcome of five years of accelerated surveillance in patients at high risk for inherited breast/ovarian cancer: report of a phase II trial.

OBJECTIVE: To assess the outcome of accelerated patient surveillance in patients at high risk for inherited breast or ovarian cancer. METHODS: Using stringent inclusion criteria, 57 high-risk patients (7 positive for BRCA1/2 mutations, 39 mutation negative, and 11 unaffected) were recruited from a genetic testing protocol for inherited breast/ovarian cancer and were followed for 5 years (192.5 total patient years). Patients received twice annual physical examinations, imaging studies, measurement of CA125 and CA15-3, psychometric measurements, and unstructured interviews by a psychologist. RESULTS: When mutation (+) and mutation (-) patients were compared, there were no significant differences in the development of disease metastasis, recurrence, or new cancers. No unaffected patients developed cancer. Management of osteoporosis, sexual function, and psychological distress were major concerns. CONCLUSIONS: Our data suggest that all patients with remarkable family history, regardless of their mutation status, may be at substantially increased risk for disease progression and development of new cancers, which is often not ovarian or recurrent breast cancer. Although prophylactic surgery is important in decreasing cancer recurrence in mutation carriers, increased surveillance with physical examinations and psychological support is also valuable and acceptable to such high-risk patients.

Adult↗
PubMed1998

Identification and haplotype analysis of apolipoprotein B-100 Arg3500-->Trp mutation in hyperlipidemic Chinese.

DNA screening for apolipoprotein (apo) B-100 mutations was performed in hyperlipidemic Chinese. The apo B-100 gene segment surrounding previously identified familial defective apo B-100 (FDB) mutations was amplified by PCR and subjected to single-strand conformation polymorphism (SSCP) analysis. One subject's aberrant SSCP band was cloned and sequenced to study the molecular lesions. A recurrent ArgCGG-to-TrpTGG mutation (R3500W) in the codon 3500 of the apo B-100 gene was identified. The C-to-T transition creates a NlaIII site and permits rapid restriction analysis of the mutation. A total of 373 hyperlipidemic patients and 309 controls were screened for R3500W. Nine unrelated subjects were shown to be heterozygous for the mutation, and no R3500W carriers were found in the control group (P = 0.004). Six polymorphic markers, including five restriction fragment length polymorphisms and one hypervariable repeat region, were used for haplotype analysis on the mutant allele. In two families, the R3500W mutation could be unambiguously assigned to a unique haplotype XbaI-/MaeI+/MspI+/EcoRI+/ Eco57I+/34 3'HVR repeats; in the other seven unrelated heterozygotes, this finding was consistent when an unequivocal haplotype was deduced. The results suggest that all R3500W alleles are identical by descent in our population. The fact that the same mutant allele was identified in other Asians with FDB indicates a common Asian origin for the R3500W mutations.

Adult↗
PubMed1975

Mutator genes and selection for the mutation rate in bacteria.

Gene frequencies in populations of haploid, asexual organisms are described by linear recurrence equations. Several models in which the mutation rate is controlled by one locus and the fitness is controlled at one or more other loci are developed. It is shown that good approximations can be introduced to give explicit solutions for the course of selection in these models. It is shown that a strong non-equilibrium selection for mutator genes is possible even when the presence of such a gene decreases the fitness of an individual. Experiments that corroborate these conclusions are discussed along with the effects of population size that determine the applicability of these results to natural populations.

Alleles↗
PubMed2005

[Molecular targeted therapy--non-small-cell lung cancer and gefitinib].

Gefitinib (Iressa, ZD 1839) is an orally bioavailable small molecule that selectively inhibits epidermal growth factor receptor(EGFR) tyrosine kinase activity. Gefitinib causes a dramatic response in approximately 10% to 20% of patients with non-small-cell lung cancer (NSCLC) who receive prior chemotherapy. Studies of gefitinib in combination chemotherapy in first-line therapy of advanced NSCLC have, however, failed to show improvement of survival. Gefitinib also failed to prolong survival in a placebo controlled clinical trial for patients with pretreated advanced NSCLC. In addition, gefitinib did not improve survival as maintenance therapy after chemoradiation in patients with Stage III NSCLC. A possible explanation for the lack of a survival benefit seen in these studies might be failure to select of patients suitable for gefitinib treatment. Empirically, and also in phase II trials, a good clinical response has been observed most frequently in women, nonsmokers, patients with adenocarcinomas, and East Asian patients. Recently, mutations and amplifications of the EGFR gene identified in a subset of NSCLC have been reported to be useful for prediction of enhanced sensitivity to gefitinib. It is also known that some recurrent tumors have a secondary mutation in the EGFR kinase domain, T 790 M, conferring drug resistance. In Japan, a significant number of patients often develop fatal interstitial lung disease after the introduction of gefitinib, although it is, in general, well tolerated. In the future, we must demonstrated benefits of gefitinib treatment in prospective clinical trials by recruiting patients selected on the basis of biological characteristics. It is also important to further elucidate various issues that include other determinants of gefitinib sensitivity, other mechanisms of resistance to gefitinib or mechanisms or predictive factors of interstitial lung disease by close collaboration among clinicians and basic researchers.

Antineoplastic Agents↗
PubMed1994

Association of idiopathic venous thromboembolism with single point-mutation at Arg506 of factor V.

Abnormal coagulation factor V may underlie the thrombotic events associated with resistance to activated protein C (APC). We analysed 27 consecutive patients with documented idiopathic (recurrent) thromboembolism for the occurrence of point mutations within the APC sensitive regions of blood coagulation factor V. In 10 patients we observed a single basepair mutation resulting in a substitution of Arg506 to Gln. This mutation was significantly linked to in-vitro resistance to APC in these subjects. This mutation at Arg506 of factor V may form the molecular basis for the thrombotic events associated with APC resistance.

Adult↗
PubMed1992

Parental origin and germline mosaicism of deletions and duplications of the dystrophin gene: a European study.

Knowledge about the parental origin of new mutations and the occurrence of germline mosaicism is important for estimating recurrence risks in Duchenne (DMD) and Becker muscular dystrophy (BMD). However, there are problems in resolving these issues partly because not all mutations can as yet be directly detected, and additionally because genetic ratios are very sensitive to ascertainment bias. In the present study, therefore, analysis was restricted to currently detectable mutations (deletions and duplications) in particular types of families which tend to be rare. In order to obtain sufficient data we pooled results from 25 European centers. In mothers of affected patients who were the first in their family with a dystrophin gene deletion or duplication, the ratio between the paternal and the maternal origin of this new mutation was 32:49 (binomial test P = 0.075) for DMD. In five BMD families the ratio between paternal and maternal origin of new mutations was 3:2. Recurrence risk because of maternal germline mosaicism was studied in sisters or subsequent sibs of isolated cases with an apparently new detectable mutation. In 12 out of 59 (0.20; 95% CI 0.10-0.31) transmissions of the risk haplotype the DMD mutation was transmitted as well. No recurrences were found in nine BMD families.

Chromosome Deletion↗