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1.

Background

Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant disease with a high risk for colorectal and endometrial cancer caused by germline mutations in DNA mismatch-repair genes (MMR). HNPCC accounts for approximately 2 to 5% of all colorectal cancers. Here we present 6 novel mutations in the DNA mismatch-repair genes MLH1, MSH2 and MSH6.

Methods

Patients with clinical diagnosis of HNPCC were counselled. Tumor specimen were analysed for microsatellite instability and immunohistochemistry for MLH1, MSH2 and MSH6 protein was performed. If one of these proteins was not detectable in the tumor mutation analysis of the corresponding gene was carried out.

Results

We identified 6 frameshift mutations (2 in MLH1, 3 in MSH2, 1 in MSH6) resulting in a premature stop: two mutations in MLH1 (c.2198_2199insAACA [p.N733fsX745], c.2076_2077delTG [p.G693fsX702]), three mutations in MSH2 (c.810_811delGT [p.C271fsX282], c.763_766delAGTGinsTT [p.F255fsX282], c.873_876delGACT [p.L292fsX298]) and one mutation in MSH6 (c.1421_1422dupTG [p.C475fsX480]). All six tumors tested for microsatellite instability showed high levels of microsatellite instability (MSI-H).

Conclusions

HNPCC in families with MSH6 germline mutations may show an age of onset that is comparable to this of patients with MLH1 and MSH2 mutations.  相似文献   

2.

Background

A large number of distinct mutations in the BRCA1 and BRCA2 genes have been reported worldwide, but little is known regarding the role of these inherited susceptibility genes in breast cancer risk among Indian women. We investigated the distribution and the nature of BRCA1 and BRCA2 germline mutations and polymorphisms in a cohort of 204 Indian breast cancer patients and 140 age-matched controls.

Method

Cases were selected with regard to early onset disease (≤40 years) and family history of breast and ovarian cancer. Two hundred four breast cancer cases along with 140 age-matched controls were analyzed for mutations. All coding regions and exon-intron boundaries of the BRCA1 and BRCA2 genes were screened by heteroduplex analysis followed by direct sequencing of detected variants.

Results

In total, 18 genetic alterations were identified. Three deleterious frame-shift mutations (185delAG in exon 2; 4184del4 and 3596del4 in exon 11) were identified in BRCA1, along with one missense mutation (K1667R), one 5'UTR alteration (22C>G), three intronic variants (IVS10-12delG, IVS13+2T>C, IVS7+38T>C) and one silent substitution (5154C>T). Similarly three pathogenic protein-truncating mutations (6376insAA in exon 11, 8576insC in exon19, and 9999delA in exon 27) along with one missense mutation (A2951T), four intronic alterations (IVS2+90T>A, IVS7+75A>T, IVS8+56C>T, IVS25+58insG) and one silent substitution (1593A>G) were identified in BRCA2. Four previously reported polymorphisms (K1183R, S1613G, and M1652I in BRCA1, and 7470A>G in BRCA2) were detected in both controls and breast cancer patients. Rare BRCA1/2 sequence alterations were observed in 15 out of 105 (14.2%) early-onset cases without family history and 11.7% (4/34) breast cancer cases with family history. Of these, six were pathogenic protein truncating mutations. In addition, several variants of uncertain clinical significance were identified. Among these are two missense variants, one alteration of a consensus splice donor sequence, and a variant that potentially disrupts translational initiation.

Conclusion

BRCA1 and BRCA2 mutations appear to account for a lower proportion of breast cancer patients at increased risk of harboring such mutations in Northern India (6/204, 2.9%) than has been reported in other populations. However, given the limited extent of reported family history among these patients, the observed mutation frequency is not dissimilar from that reported in other cohorts of early onset breast cancer patients. Several of the identified mutations are unique and novel to Indian patients.  相似文献   

3.
Chronic granulomatous disease (CGD) is an inheritable and genetically heterogeneous disease resulting from mutations in different subcomponents of the NADPH oxidase system. Mutations in the NCF2 gene account for <5% of all cases of CGD. We analyzed the clinical and laboratory findings of CGD with mutations in the NCF2 gene from amongst our cohort of CGD patients. A homozygous mutation (c.835_836delAC, p.T279fsX294), a deletion in NCF2 gene was found in two cases. In the third case, two heterozygous mutations were detected, IVS13-2A>T on one allele and c.1099C>T (p.) on the other allele. The mother of this child was a carrier for the IVS13-2A>T mutation. All three cases had colitis, and it was the initial symptom in two patients. One of the patients also developed a lung abscess due to Nocardia cyriacigeorgica.  相似文献   

4.
5.

Background

Familial adenomatous polyposis (FAP) is an autosomal dominant-inherited colorectal cancer syndrome, caused by germline mutations in the APC gene. Recently, biallelic mutations in MUTYH have also been identified in patients with multiple colorectal adenomas and in APC-negative patients with FAP. The aim of this work is therefore to determine the frequency of APC and MUTYH mutations among FAP families from two Spanish populations.

Methods

Eighty-two unrelated patients with classical or attenuated FAP were screened for APC germline mutations. MUTYH analysis was then conducted in those APC-negative families and in 9 additional patients from a previous study. Direct sequencing, SSCP analysis and TaqMan genotyping were used to identify point and frameshift mutations, meanwhile large rearrangements in the APC gene were screened by multiplex ligation-dependent probe amplification (MLPA).

Results

APC germline mutations were found in 39% of the patients and, despite the great number of genetic variants described so far in this gene, seven new mutations were identified. The two hotspots at codons 1061 and 1309 of the APC gene accounted for 9,4% of the APC-positive families, although they were underrepresented in Galician samples. The deletion at codon 1061 was not found in 19 APC-positive Galician patients but represented 23% of the Catalonian positive families (p = 0,058). The same trend was observed at codon 1309, even though statistical analysis showed no significance between populations. Twenty-four percent of the APC-negative patients carried biallelic MUTYH germline mutations, and showed an attenuated polyposis phenotype generally without extracolonic manifestations. New genetic variants were found, as well as the two hotspots already reported (p.Tyr165Cys and p.Gly382Asp).

Conclusion

The results we present indicate that in Galician patients the frequency of the hotspot at codon 1061 in APC differs significantly from the Catalonian and also other Caucasian populations. Similar results had already been obtained in a previous study and could be due to the genetic isolation of the Galician population. MUTYH analysis is also recommended for all APC-negative families, even if a recessive inheritance is not confirmed.  相似文献   

6.

Introduction

X-linked agammagobulinemia (XLA) is a primary immunodeficiency disorder caused by Bruton's tyrosine kinase (Btk) gene mutation. Recent studies suggested genotype-phenotype correlation in XLA, but a definitive association remains controversial.

Patients and Methods

We examined the relationship between specific Btk gene mutations and severity of clinical presentation in 62 patients with XLA. Disease severity was assessed by the age of disease onset and the presence of severe infections, while mutations were classified into severe and mild based on structural and functional consequence by bioinformatics analysis.

Results

Fifty-six Btk mutations were identified in 62 patients from 57 kindreds. Variation in phenotypes was observed, and there was a tendency of association between genotype and age of disease onset as well as occurrence of severe infections.

Conclusion

A critical analysis of the circumstances upon presentation also revealed that under-recognition of recurrent infections and relevant family history are important hurdles to timely diagnosis of XLA.  相似文献   

7.

Background

Ocular albinism type 1 (OA1) is an X-linked ocular disorder characterized by a severe reduction in visual acuity, nystagmus, hypopigmentation of the retinal pigmented epithelium, foveal hypoplasia, macromelanosomes in pigmented skin and eye cells, and misrouting of the optical tracts. This disease is primarily caused by mutations in the OA1 gene.

Methods

The ophthalmologic phenotype of the patients and their family members was characterized. We screened for mutations in the OA1 gene by direct sequencing of the nine PCR-amplified exons, and for genomic deletions by PCR-amplification of large DNA fragments.

Results

We sequenced the nine exons of the OA1 gene in 72 individuals and found ten different mutations in seven unrelated families and three sporadic cases. The ten mutations include an amino acid substitution and a premature stop codon previously reported by our team, and eight previously unidentified mutations: three amino acid substitutions, a duplication, a deletion, an insertion and two splice-site mutations. The use of a novel Taq polymerase enabled us to amplify large genomic fragments covering the OA1 gene. and to detect very likely six distinct large deletions. Furthermore, we were able to confirm that there was no deletion in twenty one patients where no mutation had been found.

Conclusion

The identified mutations affect highly conserved amino acids, cause frameshifts or alternative splicing, thus affecting folding of the OA1 G protein coupled receptor, interactions of OA1 with its G protein and/or binding with its ligand.  相似文献   

8.

Purpose

Autosomal recessive hyper-IgE syndrome is a rare combined immunodeficiency characterized by susceptibility to viral infections, atopic eczema, high serum IgE and defective T cell activation. The genetic etiologies are diverse. Null mutations in DOCK8 and TYK2 are responsible for many cases. This study aims to provide a detailed clinical and immunological characterization of the disease and explore the underlying genetic defects among a large series of patients followed by a single center. The available data might improve our understanding of the disease pathogenesis and prognosis.

Methods

Clinical data of twenty-five patients diagnosed with AR-HIES were collected. Seventeen patients screened for STAT3, TYK2 and DOCK8 mutations.

Results

Sinopulmonary infections, dermatitis, hepatic disorders, cutaneous and systemic bacterial, fungal and viral infections were the most common clinical features. The rate of hepatic disorders and systemic infections were high. Twelve patients died with a median age of 10 years. CMV infection was the only statistically significant predicting factor for poor prognosis (early death). Three novel DOCK8 mutations and two large deletions were found in thirteen patients. No mutations found in STAT3 or TYK2 genes.

Conclusion

Autosomal recessive hyper-IgE syndrome is a combined immunodeficiency disease characterized by high morbidity and mortality rate. The different genetic background and environmental factors may explain the more severe phenotypes seen in our series. DOCK8 defect is the most common identified genetic cause. Patients with no identified genetic etiology are likely to carry mutations in the regulatory elements of genes tested or in novel genes that are yet to be discovered.  相似文献   

9.
10.

Background

Familial adenomatous polyposis (FAP) is typically characterized by multiple colonic polyps and frequent extracolonic features. Whereas the number of colonic polyps has been linked to the APC gene mutation, possible genotype-phenotype correlations largely remain to be defined for the extracolonic manifestations.

Methods

Full genomic sequencing combined with multiplex ligation-dependent probe amplification was used to identify APC gene mutations, which were correlated to the clinical presentations.

Results

10 novel APC gene mutations were identified in 11 families. A broad spectrum of extracolonic manifestations was identified in most of these individuals. Two sisters with an insertion in codon 528 (c.1582_1583insGC) both showed severe phenotypes with classical polyposis, upper gastrointestinal polyps and thyroid cancer. A woman with a 3'APC mutation (c.5030_5031insAA) developed colon cancer at age 72 as the first manifestation of attenuated FAP.

Conclusion

With an increasing number of FAP families diagnosed, a broad and variable tumor spectrum and a high frequency of extracolonic manifestations are gradually recognized. We report novel APC mutations and present two FAP cases that suggest familial aggregation of thyroid cancer and demonstrate the need to consider attenuated FAP also among elderly patients with colon cancer.  相似文献   

11.

Background

Tuberous sclerosis complex (TSC) is an autosomal dominant disease characterized by the development of multiple hamartomas in many internal organs. Mutations in either one of 2 genes, TSC1 and TSC2, have been attributed to the development of TSC. More than two-thirds of TSC patients are sporadic cases, and a wide variety of mutations in the coding region of the TSC1 and TSC2 genes have been reported.

Methods

Mutational analysis of TSC1 and TSC2 genes was performed in 84 Taiwanese TSC families using denaturing high-performance liquid chromatography (DHPLC) and direct sequencing.

Results

Mutations were identified in a total of 64 (76 %) cases, including 9 TSC1 mutations (7 sporadic and 2 familial cases) and 55 TSC2 mutations (47 sporadic and 8 familial cases). Thirty-one of the 64 mutations found have not been described previously. The phenotype association is consistent with findings from other large studies, showing that disease resulting from mutations to TSC1 is less severe than disease due to TSC2 mutation.

Conclusion

This study provides a representative picture of the distribution of mutations of the TSC1 and TSC2 genes in clinically ascertained TSC cases in the Taiwanese population. Although nearly half of the mutations identified were novel, the kinds and distribution of mutation were not different in this population compared to that seen in larger European and American studies.  相似文献   

12.

Background

PLS is a rare autosomal recessive disorder characterized by early onset periodontopathia and palmar plantar keratosis. PLS is caused by mutations in the cathepsin C (CTSC) gene. Dipeptidyl-peptidase I encoded by the CTSC gene removes dipeptides from the amino-terminus of protein substrates and mainly plays an immune and inflammatory role. Several mutations have been reported in this gene in patients from several ethnic groups. We report here mutation analysis of the CTSC gene in three Indian families with PLS.

Methods

Peripheral blood samples were obtained from individuals belonging to three Indian families with PLS for genomic DNA isolation. Exon-specific intronic primers were used to amplify DNA samples from individuals. PCR products were subsequently sequenced to detect mutations. PCR-SCCP and ASOH analyses were used to determine if mutations were present in normal control individuals.

Results

All patients from three families had a classic PLS phenotype, which included palmoplantar keratosis and early-onset severe periodontitis. Sequence analysis of the CTSC gene showed three novel nonsense mutations (viz., p.Q49X, p.Q69X and p.Y304X) in homozygous state in affected individuals from these Indian families.

Conclusions

This study reported three novel nonsense mutations in three Indian families. These novel nonsense mutations are predicted to produce truncated dipeptidyl-peptidase I causing PLS phenotype in these families. A review of the literature along with three novel mutations reported here showed that the total number of mutations in the CTSC gene described to date is 41 with 17 mutations being located in exon 7.
  相似文献   

13.

Purpose

The present study aims to estimate the prevalence of bifid mandibular canals in patients treated at the Dental Clinic of the Federal University of Paraná, Brazil.

Methods

The sample consisted of 3,024 panoramic radiographs from male (n = 1,155) and female (n = 1,869) patients (mean age 30 years). An experienced radiologist analyzed the panoramic radiographs according to the study of Langlais et al. (J Am Dental Assoc 110:923–926, 1985), which classifies bifid mandibular canals into four different types.

Results

Sixty patients (1.98 %) presented bifid mandibular canals. Specifically, 50 patients revealed bifid mandibular canals type I, while 10 patients revealed bifid mandibular canals type II. All the variations were unilateral. In addition, statistically significant results were not observed for gender distribution.

Conclusion

The present findings indicate a low prevalence of morphologic alterations of the mandibular canal in the studied population. However, the present outcome highlights the clinical relevance of investigating the radiologic morphology of the mandibular canal prior to surgical interventions.  相似文献   

14.

Background

The dominantly inherited condition familial adenomatous polyposis (FAP) is caused by germline mutations in the APC gene. Finding the causative mutations has great implications for the families. Correlating the genotypes to the phenotypes could help to improve the diagnosis and follow-up of patients.

Methods

Mutation screening of APC and the clinical characterization of 96 unrelated FAP patients from the Swedish Polyposis Registry was performed. In addition to generally used mutation screening methods, analyses of splicing-affecting mutations and investigations of the presence of low-frequency mutation alleles, indicating mosaics, have been performed, as well as quantitative real-time polymerase chain reaction to detect lowered expression of APC.

Results

Sixty-one different APC mutations in 81 of the 96 families were identified and 27 of those are novel. We have previously shown that 6 of the 96 patients carried biallelic MUTYH mutations. The 9 mutation-negative cases all display an attenuated or atypical phenotype. Probands with a genotype (codon 1250–1464) predicting a severe phenotype had a median age at diagnosis of 21.8 (range, 11–49) years compared with 34.4 (range, 14–57) years among those with mutations outside this region (P < 0.017). Dense polyposis (> 1000) occurred in 75% of the probands with a severe phenotype compared with 30% in those with mutations outside this region. The morbidity in colorectal cancer among probands was 25% at a mean age of 37.5 years and 29% at a mean age of 46.6 years.

Conclusion

Using a variety of mutation-detection techniques, we have achieved a 100% detection frequency in classical FAP. Probands with APC mutations outside codon 1250–1464, although exhibiting a less-severe phenotype, are at high risk of having a colorectal cancer at diagnosis indicating that age at diagnosis is as important as the severity of the disease for colorectal cancer morbidity.  相似文献   

15.

Background

Hypertrophic Cardiomyopathy (HCM) is a complex myocardial disorder with a recognized genetic heterogeneity. The elevated number of genes and mutations involved in HCM limits a gene-based diagnosis that should be considered of most importance for basic research and clinical medicine.

Methodology

In this report, we evaluated High Resolution Melting (HRM) robustness, regarding HCM genetic testing, by means of analyzing 28 HCM-associated genes, including the most frequent 4 HCM-associated sarcomere genes, as well as 24 genes with lower reported HCM-phenotype association. We analyzed 80 Portuguese individuals with clinical phenotype of HCM allowing simultaneously a better characterization of this disease in the Portuguese population.

Results

HRM technology allowed us to identify 60 mutated alleles in 72 HCM patients: 49 missense mutations, 3 nonsense mutations, one 1-bp deletion, one 5-bp deletion, one in frame 3-bp deletion, one insertion/deletion, 3 splice mutations, one 5'UTR mutation in MYH7, MYBPC3, TNNT2, TNNI3, CSRP3, MYH6 and MYL2 genes. Significantly 22 are novel gene mutations.

Conclusions

HRM was proven to be a technique with high sensitivity and a low false positive ratio allowing a rapid, innovative and low cost genotyping of HCM. In a short return, HRM as a gene scanning technique could be a cost-effective gene-based diagnosis for an accurate HCM genetic diagnosis and hopefully providing new insights into genotype/phenotype correlations.  相似文献   

16.

Purpose

Patients with autosomal recessive cyclic neutropenia have no known causative genetic defect yet.

Methods

Autozygosity mapping on two branches of an extended multiplex consanguineous family presenting with cyclic neutropenia or severe congenital neutropenia to look for candidate gene, followed by candidate gene selection and sequencing.

Results

A single autozygous interval on Chr17:33,901,938-45,675,414 that is exclusively shared by the affected members was identified. This interval spans 11.8 Mb and contains 30 genes. Review of these genes highlighted G6PC3 as the most likely candidate given its known role in neutrophil biology. Direct sequencing revealed a novel homozygous mutation (NM_138387.3, c.974T?>?G, p.Leu325Arg). Two of our patients had associated congenital defects that are known to occur in patients with G6PC3 mutations, including congenital heart disease and intermittent thrombocytopenia.

Conclusion

Biallelic G6PC3 defects should be considered in patients with autosomal recessive cyclic neutropenia, especially those with typical associated congenital defects.  相似文献   

17.
《Immunobiology》2020,225(3):151938
Leukocyte adhesion deficiency I (LADI) is an autosomal recessive type of primary immunodeficiency characterized by occurrence of repeated bacterial infections, impaired pus formation and wound healing. Genetic variations in the β-2 integrin subunit encoding gene ITGB2 have been implicated in causing the disorder. In the present study, we have investigated twelve patients presenting LAD1 features. After collecting clinical and family history, flow cytometry was used to determine levels of CD18 in the patients. Clinical history revealed that umbilical cord separation occurred mostly after 19 days in the patients. Recurrent skin infections were found in seven patients. Eight patients had at least one elder sibling who died due to repeated infections. All patients had marked neutrophilia with only 0.77% of neutrophils expressing CD18. Total 12 patients suffering from LAD1 were Sanger sequenced for ITGB2 gene. Five variants, including a novel p.(Cys286Phe) and four previously reported [p.(Gly273Arg), p.(Asp128Tyr), p.(Cys62*), IVS7 + 1G > A] were identified in 8 cases, while no pathogenic variant was observed in remaining four cases. This study represents the first comprehensive clinical and genetic characterization of LAD1 in Pakistani population. This will facilitate diagnosis and genetic counselling of patients with immunodeficiency disorders in Pakistani population.  相似文献   

18.

Objective

To report a cohort of children with periodic fever syndromes (PFS) from Southeast Michigan.

Methods

A retrospective review of medical records for patients referred for periodic fever over 5 years.

Results

Sixty-six patients including 21 FMF, 15 PFAPA, four TRAPS and one patient with combined HIDS and FMF were included. In addition, 25 patients were categorized as clinical PFS (cPFS) based on their clinical features however their genetic workup was either negative or inconclusive. Majority of the patients with FMF were from Middle Eastern background (88 %), but positive family history was noted in only 55 % of cases. Mean age at diagnosis was 40.8 months with a mean delay in diagnosis of 24 months. Most common MEFV mutations were p.M694V and p.M694I. Four patients with TRAPS were from mixed European descent and age at onset of symptoms was 6, 12, 12, and 84 months respectively. TNFRSF1A sequence variants in the TRAPS patients included p.R121Q (R92Q) and p.C99G (C70G); one patient had a rare occurrence of a concurrent p.V726A/-MEFV mutation. One patient with HIDS and FMF presented with atypical overlapping PFS clinical manifestations and genetic evaluation showed a unique combination of p.I268T/p.V377I MVK mutations and p.E230K/-MEFV variant. All patients with PFAPA group were from mixed European descent, symptoms started at a mean age of 34.6 months with a mean delay in diagnosis of 23.3 months. Symptoms started during infancy in six patients. All patients fulfilled the diagnostic criteria for PFAPA. The mean age of onset of symptoms in cPFS group was 17.2 months. Empiric colchicine and glucocorticosteroids controlled flares in majority of patients with cPFS. No evidence of amyloidosis was found in this entire cohort of 66 patients after a mean of 29.2 months of follow-up.

Conclusion

PFS can present with atypical manifestations and should not be excluded based on a negative family history. Concomitant mutations in different autoinflammatory disorders genes can be present and possibly explain atypical manifestations. Various therapies may be considered even if genetic testing is inconclusive or negative.  相似文献   

19.

Background

Oncogenic point mutations in KIT or PDGFRA are recognized as the primary events responsible for the pathogenesis of most gastrointestinal stromal tumors (GIST), but additional genomic alterations are frequent and presumably required for tumor progression. The relative contribution of such alterations for the biology and clinical behavior of GIST, however, remains elusive.

Methods

In the present study, somatic mutations in KIT and PDGFRA were evaluated by direct sequencing analysis in a consecutive series of 80 GIST patients. For a subset of 29 tumors, comparative genomic hybridization was additionally used to screen for chromosome copy number aberrations. Genotype and genomic findings were cross-tabulated and compared with available clinical and follow-up data.

Results

We report an overall mutation frequency of 87.5%, with 76.25% of the tumors showing alterations in KIT and 11.25% in PDGFRA. Secondary KIT mutations were additionally found in two of four samples obtained after imatinib treatment. Chromosomal imbalances were detected in 25 out of 29 tumors (86%), namely losses at 14q (88% of abnormal cases), 22q (44%), 1p (44%), and 15q (36%), and gains at 1q (16%) and 12q (20%). In addition to clinico-pathological high-risk groups, patients with KIT mutations, genomic complexity, genomic gains and deletions at either 1p or 22q showed a significantly shorter disease-free survival. Furthermore, genomic complexity was the best predictor of disease progression in multivariate analysis.

Conclusions

In addition to KIT/PDGFRA mutational status, our findings indicate that secondary chromosomal changes contribute significantly to tumor development and progression of GIST and that genomic complexity carries independent prognostic value that complements clinico-pathological and genotype information.  相似文献   

20.

Introduction

Chronic granulomatous disease is a rare inherited immunodeficiency syndrome caused by mutations in four genes encoding essential nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex components.

Material and methods

Clinical, functional, and molecular investigations were conducted in 15 Jordanian CGD patients from nine families.

Results and Discussion

Fourteen patients were children of consanguineous parents and suffered from autosomal recessive (AR) CGD forms with mutations in the CYBA, NCF1, and NCF2 genes encoding p22phox, p47phox, and p67phox proteins, except for one patient in whom the mutation’s location was not found. One patient had an extremely rare X+CGD subtype resulting from a novel missense mutation (G1234C) in exon 10 of CYBB. We found a genetic heterogeneity in the Jordanian families with a high frequency of rare ARCGD, probably because consanguineous marriages are common in Jordan. No clear correlation between the severity of the clinical symptoms and the CGD types could be established.  相似文献   

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