Genetic Screening and Analysis of LKB1 Gene in Chinese Patients with Peutz-Jeghers Syndrome.

BACKGROUND Peutz-Jeghers syndrome (PJS) is an autosomal dominant genetic disease. It severely decreases patient quality of life and leads elevated cancer risk. Germline mutation of LKB1 is the leading cause of familial PJS. MATERIAL AND METHODS To characterize the germline mutation of LKB1 gene in Chinese familial and sporadic PJS patients, 14 PJS families, 5 sporadic PJS patients, and 250 healthy adults were collected and genomic DNAs of peripheral blood were extracted. Mutation screenings of LKB1 were performed using MLPA (multiplex ligation-dependent probe amplification), PCR, direct sequencing, and PCR-DHPLC (denaturing high-performance liquid chromatography). RESULTS A total of 12 kinds of germline mutations were found in 9 familial PJS patients, most of which were point mutations (7/12); 4 large deletions of LKB1 were also observed. Of the 12 mutations, 7 were pathogenic (2 were de novo), 4 were just polymorphisms, and 1 was indefinitely pathogenic. No pathogenic mutation in exons of the LKB1 gene was detected in the 5 sporadic PJS patients. The mutation detection rate for the LKB1 gene was 85.7% in our Chinese familial PJS and 63.2% in all Chinese PJS patients. Eight familial PJS patients were identified with pathogenic germline mutations in 14 unrelated families (57.1%). Further methylation detection and analysis showed promoter methylation in carcinomatous polyps. CONCLUSIONS LKB1 gene germline mutation with pathogenic effect is a common cause of familial PJS in Chinese patients; however, it is not the only molecular pathogen of PJS. Methylation in the LKB1 gene promoter region may cause carcinomatous change in intestinal polyps.

[Analysis of C.3925_3929 deletional mutations of APC gene in pedigrees with familial adenomatous polyposis].

OBJECTIVE: To analyze the characteristics of germline mutations of adenomatous polyposis coli (APC) gene in pedigrees affected with familial adenomatous polyposis (FAP). METHODS: Genomic DNA was extracted from peripheral blood samples from members of the 13 FAP pedigrees. Multiplex ligation-dependent probe amplification (MLPA) was used to detect large fragment deletions of the APC gene. Subsequently, potential mutation was screened from all exons of the APC gene with PCR amplification and direct sequencing. RESULTS: Germline mutations have been identified in 5 FAP pedigrees, which included c.3184_3187delCAAA, c.5432C>T, c.3925_3928delAAAA and c.3925_3929del AAAAG(in two pedigrees). Small deletional mutations were found primarily in the area of AAAAG tandem repeat sequences. CONCLUSION: C.3925_3929 located in AAAAG tandem repeats is probably the hot spot for APC gene mutations, which are mostly deletional mutations, especially the 5 bp base deletion at codon 1309.

A new familial gastric cancer-related gene polymorphism: T1151A in the mismatch repair gene hMLH1.

We designed to understand the effects of the T1151A gene polymorphism in the hMLH1 gene on the pathogenesis of familial gastric cancer. Peripheral blood DNA from 113 patients with familial gastric cancer or suspected familial gastric cancer that were newly identified in the same year, along with 180 healthy subjects, was subjected to polymerase chain reaction-denaturing high-performance liquid chromatography (PCR-DHPLC) and DNA sequencing of exon 12 in the hMLH1 gene. Our results as following, the T1151A detection rate was remarkably higher in patients with familial gastric cancer or suspected familial gastric cancer compared to normal control patients (P < 0.05). Stratified analysis showed that there was a significant difference in the detection rate between the control group and elderly patients whose age of onset was greater than 50 years old (P < 0.05). The detection rate of patients from high-risk families were relatively high (P < 0.05). An especially significant distribution was observed in patients who had suffered precancerous diseases related to gastric cancer (P < 0.01). In conclusion, familial gastric carcinoma families in China carrying the T1151A polymorphism may have a higher risk of suffering from gastric cancer. This gene polymorphism can be used as a candidate screening index for high-risk populations.

[Association of IVS10+12G>A polymorphism in hMSH2 gene with colorectal cancer in Chinese].

OBJECTIVE: To investigate the association of the single-nucleotide polymorphism (SNP) IVS10+12 G>A in hMSH2 gene with colorectal cancer in a Chinese population of Jiangsu province. METHODS: A case-control study to investigate whether this SNP affects the risk of developing colorectal cancer was conducted. Subjects included 108 colorectal cancer patients and 180 healthy individuals. Peripheral white blood cell DNA was obtained from all subjects. The hMSH2 gene IVS10+12 G>A was genotyped using a PCR-based DHPLC, the existence of IVS10+12 G>A was verified by DNA sequencing. RESULTS: The allele frequency of the IVS10+12 G>A in the hMSH2 gene in the healthy individuals was 51.7%. There was significant difference in the frequency of the IVS10+12 G>A between patients and healthy controls (P<0.05), and between familial patients and healthy controls (P<0.05). There was also significant difference of the frequency of the IVS10+12 G>A between patients younger than 50 years, and patients with high consumption of fried food and pickled vegetable and healthy controls respectively (P<0.05). CONCLUSION: This SNP may be associated with colorectal cancers in Chinese. Further investigation with larger sample size is needed.

Bioinformatics identification of lncRNA biomarkers associated with the progression of esophageal squamous cell carcinoma.

The poor outcome of patients with esophageal squamous cell carcinoma (ESCC) highlights the importance of the identification of novel effective prognostic biomarkers. Long non­coding RNAs (lncRNAs) serve regulatory roles in various types of cancer. The aim of the present study was to investigate the lncRNA expression profile in ESCC and to identify lncRNAs associated with the prognosis of ESCC by performing comprehensive bioinformatics analyses. The RNA­sequencing (Seq) expression dataset GSE53625 generated from ESCC samples was used as a training dataset. Additional RNA­Seq datasets relative to ESCC samples were downloaded from The Cancer Genome Atlas and used as a validation dataset. Data were screened using the limma package, and differentially expressed lncRNAs between early­ and late­stage ESCC were identified. A random forest algorithm was used to select the optimal lncRNA biomarkers, which were then analyzed using the support vector machine (SVM) algorithm with R software. The identified lncRNA biomarkers were examined in the validation dataset by bidirectional hierarchical clustering and using an SVM classifier. Subsequently, univariate and multivariate Cox regression analyses were performed to analyze the potential ability lncRNAs to predict the survival rate of patients with ESCC. By examining the training group, 259 deregulated lncRNAs between early­ and advanced­stage ESCC were identified. Further bioinformatics analyses identified a nine­lncRNA signature, including AC098973, AL133493, RP11­51M24, RP11­317N8, RP11­834C11, RP11­69C17, LINC00471, LINC01193 and RP1­124C. This nine­lncRNA signature was used to predict the tumor stage and patient survival rate with high reliability and accuracy in the training and validation datasets. Furthermore, these nine lncRNA biomarkers were primarily involved in regulating the cell cycle and DNA replication, and these processes were previously identified to be associated with the progression of ESCC. The identified nine­lncRNA signature was identified to be associated with the tumor stage, and could be used as predictor of the survival rate of patients with ESCC.

Altered distribution of beta-catenin and prognostic roles in colorectal carcinogenesis.

OBJECTIVE: Although beta-catenin cytoplasmic stabilization and nuclear translocation play a key role in initiation of colorectal cancer (CRC), the mechanisms are far from clear. The aim of this study was to investigate the relation of expressions of cyclooxygenase (COX)-2 and E-cadherin, and the beta-catenin gene exon 3 mutation to the altered distribution of beta-catenin, and their roles in CRC progression and prognosis. MATERIAL AND METHODS: Expressions of beta-catenin, COX-2 and E-cadherin in 96 tissue specimens were detected by immunohistochemistry, and mutation of beta-catenin gene exon 3 was screened by polymerase chain reaction (PCR) and denaturing high-performance liquid chromatography (DHPLC). RESULTS: Cytoplasmic/nuclear expression of beta-catenin and reduced membranous expression of E-cadherin were associated, respectively, with the earlier and later stages of sequential colorectal carcinogenesis (p<0.05). The altered distribution of beta-catenin was significantly associated with both high Dukes' stages and poor differentiation of CRC (p<0.05). It also had a parallel relationship with COX-2 overexpression (p<0.05, Spearman's rank analysis), but not with reduced E-cadherin expression. Kaplan-Meier analysis showed a significantly worse survival rate for CRC patients with altered expression of beta-catenin (p<0.05, log-rank test). Nevertheless, we failed to find any exon 3 mutation of beta-catenin gene in all 60 cases of CRC. CONCLUSIONS: Altered distribution of beta-catenin occurs in the early stage of colorectal carcinogenesis and has a parallel relationship with COX-2 overexpression. It may serve as a potential marker for the progression and prognosis of CRC. The exon 3 mutation did not appear contributive to the abnormal expression of beta-catenin in CRCs in a Chinese population.

[Germline mutation of adenomatous polyposis coli gene in Chinese patients with familial adenomatous polyposis].

OBJECTIVE: To explore the characteristics of adenomatous polyposis coli (APC) gene germline mutations in Chinese patients with familial adenomatous polyposis (FAP). METHODS: Eighteen members from nine FAP pedigrees were studied by using multiplex ligation-dependent probe amplification(MLPA) to detect large fragment deletion of APC gene. Then, PCR were performed to amplify all exons of APC gene for mutation screening by denaturing high performance liquid chromatography (DHPLC). When abnormal elution profile of DHPLC was found, DNA sequencing was performed to determine the mutations. RESULTS: Mutations were identified in three pedigrees among the nine pedigrees. They were c.3184_3187 del CAAA in pedigree 2, c.5432C to T in pedigree 4 and c.3925_3929 del AAAAG in pedigree 9 respectively. Among them, c.5432C to T was novel. CONCLUSION: APC gene germline mutations can cause the development of FAP. The FAP patients without APC gene germline mutations could be caused by other mechanisms.

[Promoter hypermethylation and loss of heterozygosity of the APC gene in patients with familial adenomatous polyposis].

OBJECTIVE: To investigate the status of hypermethylation in the promoter 1A region of the adenomatus polyposis coli (APC) gene in 3 familial adenomatous polyposis (FAP) pedigrees and to screen large fragment deletions in the APC gene. METHODS: DNA from tumor tissues and corresponding normal tissues of 5 FAP patients was modified by sodium bisulfite. Then the methylation status of the APC gene was analyzed by methylation specific-PCR (MSP) and DNA sequencing. Multiplex ligation-dependent probe amplification (MLPA) was used to screen aberrations involving large fragments from all the 15 exons and promoter region of APC gene. RESULTS: No methylation was present in normal tissues. Hypermethylation was found in tumor tissues of one proband and her son. Loss of heterozygosity was observed in another patient from the same FAP family. CONCLUSION: Aberrant methylation of the APC promoter region provides an important mechanism for impairing APC function and may occur early during colon neoplasia progression. Loss of heterozygosity may play a role in patients with classical polyposis.

Analysis of human MutS homolog 2 missense mutations in patients with colorectal cancer.

Germline mutations of DNA mismatch repair gene human MutS homolog 2 (hMSH2) are associated with hereditary nonpolyposis colorectal cancer (HNPCC). A total of one-third of these mutations are missense mutations. Several hMSH2 missense mutations have been identified in patients in East Asia, although their function has not been evaluated. In the present study, the role of ten hMSH2 missense mutations in the pathogenesis of colorectal cancer was examined. The hMSH2/hMSH6 protein interaction system was established using yeast two-hybrid screening. Next, the missense mutations were analyzed for their ability to affect the protein interaction of hMSH2 with its partner hMSH6. Additionally, the Sorting Intolerant from Tolerant tool was applied to predict the effects of different amino acid substitutions. The results demonstrated that certain hMSH2 mutations (L173R and C199R) caused a significant functional change in the human hMutSα complex and were identified to be pathological mutations. The Y408C, D603Y, P696L and S703Y mutations partially affected interaction and partly affected the function of hMSH2. The remaining four variants, T8M, I169V, A370T and Q419K, may be non-functional polymorphisms or could affect protein function through other molecular mechanisms. The present study evaluated the functional consequences of previously unknown missense mutations in hMSH2, and may contribute to improved clinical diagnosis and mutation screening of HNPCC.

Resveratrol induced apoptosis in human gastric carcinoma SGC-7901 cells via activation of mitochondrial pathway.

BACKGROUND: Resveratrol is a natural polyphenolic compound and its anticancer effect has been receiving considerable attention. Previous studies showed that resveratrol could inhibited the growth of human gastric carcinoma cells and apoptosis induction was an important mechanism. However, whether mitochondrial pathway was involved in resveratrol-induced apoptosis in human gastric cancer was not very clear. METHODS: The cells were examined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, Annexin V/PI staining assay, mitochondrial membrane depolarization, cell morphological assessment, cytochrome c release assay, and Western blotting assay. RESULTS: In this study, we found that resveratrol induced apoptosis in human gastric carcinoma SGC-7901 cells. Cleaved PARP was observed and caspase-3 was activated by resveratrol. Next, the mitochondrial membrane potential of cells dissipated after the cells were treated by resveratrol. Moreover, we found that pro-caspase 9 was downregulated and cytochrome c released from mitochondrial to the cytosol. We also found that the expression ratio of Bax/Bcl-2 was increased in the treated cells. We finally showed that resveratrol inhibited the proliferation of SGC-7901 xerograph in vivo. CONCLUSIONS: Collectively, our findings demonstrate that resveratrol triggers apoptosis via mitochondrial pathway in SGC-7901 cells, which provide more basis for resveratrol acting as antitumor agents in cancer therapy.

[Simultaneous detection of polymorphisms in the 3'- and 5'-UTR of thymidylate synthase gene using denaturing high-performance liquid chromatography].

Polymorphism which is either in the thymidylate synthase (TS)enhancer region (TSER) of the 5-primer untranslation region (5' UTR) or in the 3-primer untranslation region (3' UTR) has been reported to be associated with the alterations in TS mRNA and protein levels. The TSER is characteristic of the presence of variable double (2R) and triple (3R) number tandem repeats (VNTRs). In addition to VNTRs, single nucleotide polymorphism (SNPs) in 3R, as well as the polymorphism of the fragment length(FLP) in the TS 3'-UTR which is characteristic of the presence or absence of a 6 bp- nucleotide fragment, has recently been reported to be associated with the response to 5-fuorouracil (5-FU)-based chemo-therapy. The aim of the present study was to develop a specifc denaturing high-performance liquid chromatography (DHPLC) method for the rapid and simultaneous detection of these variations in clinical samples. Multi-PCR primers were designed to amplify the two regions simultaneously, The 8.6 min DHPLC gradient was optimized to include the analysis of multiplexed TSER/3' UTR chromatogram peaks, allowing for the simultaneous detection of 28 bp VNTRs and 6 bp FLP under nondenaturing conditions (50). The optimal melting temperature was determined experimentally for the detection of SNP in the TSER VNTRs. Finally, the DHPLC analysis was verified in parallel with PCR-RFLP and sequencing. The optimized DHPLC method resolved 100% of the known TS variations, discriminated between homozygous and heterozy-gous genotypes. This developed DHPLC method could permit the rapid, sensitive, and accurate identification of the TS genotypes (VNTRs, SNPs, and FLP).

A novel P755L mutation in LRRK2 gene associated with Parkinson's disease.

Parkinson's disease is a common neurodegenerative disorder. The identification of leucine-rich repeat kinase 2 (LRRK2) gene mutations as a cause of Parkinson's disease has greatly expanded our knowledge of the genetic and molecular pathogenesis of this disorder. By denaturing high-performance liquid chromatography and gene sequencing in patients and controls, we identified a novel frequent heterozygous 2264C-->T substitution, which causes a proline-to-leucine mutation (P755L) in LRRK2 gene. In our sample of 598 patients of Chinese Han ancestry, 12 cases carried the same LRRK2 mutation. Our results indicated that this single mutation was implicated in 2% of sporadic patients. We suggest that testing for this mutation will be important in the management and genetic counseling of patients with Parkinson's disease.

[A novel APC gene germline mutation in a familial adenomatous polyposis pedigree].

OBJECTIVE: To detect the adenomatous polyposis coli (APC) gene germline mutation in the proband and her family members with familial adenomatous polyposis (FAP). METHODS: The diagnosis of a patient with FAP was validated by colonoscopy, pathology and the family history. The systematic screening with multiplex ligation-dependent probe amplification (MLPA), denaturing high-performance liquid chromatography (DHPLC) and DNA sequencing were carried out to detect APC gene germline mutations. RESULTS: A novel mutation c.1999 C >T (Q667X) of APC, which leads to premature termination of the protein, was identified in this family. This mutation manifested an aggressive form of FAP with early onset of colorectal adenocarcinoma and colonic adenoma. CONCLUSION: The mutation of APC Q667X is the cause of clinical phenotype of this family with FAP, and the prophylactic colectomy for the affected family members should be considered.

[The expression of mutation p53 gene from circulating cancer cells of peripheral blood and the clinical significance in detecting the patients with colorectal cancer].

OBJECTIVE: To study the clinical significance of detecting p53 gene mutation expression in colorectal cancer cells of peripheral blood. METHODS: Flow cytometry (FCM) was used to detect p53 gene mutation expression in peripheral blood cancer cells of 128 patients with colorectal cancer. Experimental data were analyzed by SPSS (v.11.0) software. RESULTS: The lymph node metastasis showed the significant difference statistically (P<0.01) between p53 positive and negative expression in the colorectal cancer patients. The mutation p53 expression associated with existing histological differentiation (r=0.8476, P<0.05). A lymph node metastasis difference was observed between left and right colorectal cancers of mutation p53 positive expression. CONCLUSION: Detecting the mutation p53 expression in cancer cells of peripheral blood might be helpful to the early diagnosis of colorectal cancer.

Analysis of Small Fragment Deletions of the APC gene in Chinese Patients with Familial Adenomatous Polyposis, a Precancerous Condition.

BACKGROUND: Familial adenomatous polyposis (FAP) is an autosomal dominant inherited disease mainly caused by mutations of the adenomatous polyposis coli (APC) gene with almost complete penetrance. These colorectal polyps are precancerous lesions that will inevitable develop into colorectal cancer at the median age of 40-year old if total proctocolectomy is not performed. So identification of APC germline mutations has great implications for genetic counseling and management of FAP patients. In this study, we screened APC germline mutations in Chinese FAP patients, in order to find novel mutations and the APC gene germline mutation characteristics of Chinese FAP patients. MATERIALS AND METHODS: The FAP patients were diagnosed by clinical manifestations, family histories, endoscope and biopsy. Then patients peripheral blood samples were collected, afterwards, genomic DNA was extracted. The mutation analysis of the APC gene was conducted by direct polymerase chain reaction (PCR) sequencing for micromutations and multiplex ligation-dependent probe amplification (MLPA) for large duplications and/or deletions. RESULTS: We found 6 micromutations out of 14 FAP pedigrees, while there were no large duplications and/or deletions found. These germline mutations are c.5432C>T(p. Ser1811Leu), two c.3926_3930delAAAAG (p.Glu1309AspfsX4), c.3921_3924delAAAA (p.Ile1307MetfsX13), c3184_3187delCAAA(p.Gln1061AspfsX59) and c4127_4126delAT (p.Tyr1376LysfsX9), respectively, and all deletion mutations resulted in a premature stop codon. At the same time, we found c.3921_3924delAAAA and two c.3926_3930delAAAAG are located in AAAAG short tandem repeats, c3184_3187delCAAA is located in the CAAA interrupted direct repeats, and c4127_4128 del AT is located in the 5'-CCTGAACA-3' ,3'-ACAAGTCC-5 palindromes (inverted repeats) of the APC gene. Furthermore, deletion mutations are mostly located at condon 1309. CONCLUSIONS: Though there were no novel mutations found as the pathogenic gene of FAP in this study, we found nucleotide sequence containing short tandem repeats and palindromes (inverted repeats), especially the 5 bp base deletion at codon 1309, are mutations in high incidence area in APC gene.

[Study of in vivo micronucleus formation in lymphocytes from the patients and its relation to malignant degrees of colorectal cancer].

OBJECTIVE: To investigate the association of the micronucleus (MN) formation in lymphocytes from patients with the malignant degrees of colorectal cancer. METHODS: The MN test in capillary blood lymphocytes was conducted in 112 patients randomly selected from in-hospital patients before therapy. Experimental data were analyzed by SPSS (v.10.1) software. RESULTS: The differences in the frequency of MN between 7 pathological types of colorectal cancers and controls were statistically significant (P<0.01). The frequency of MN increased with the decrease of the histological differentiation in colorectal cancer, and the statistically significant differences were seen between low differentiation group and the other differentiation groups in colorectal cancers. CONCLUSION: There is a significant correlation between MN formation and the malignant degrees of colorectal cancer, and MN formation will be a useful biomarker for the identification of malignant degrees of colorectal cancer before operation or for the screening of high risk subgroup.

[Clinical characteristics and mutation analysis of the LKB1 gene in a Peutz-Jeghers syndrome pedigree].

OBJECTIVE: To investigate clinical characteristics and mutation of the LKB1 gene in a Peutz-Jeghers syndrome (PJS) pedigree. METHOD: Clinical data of a PJS family were analyzed and LKB1 gene mutation was detected by systematic screening with multiplex ligation-dependent probe amplification (MLPA) and DNA sequencing. Meanwhile, two hundred and fifty healthy adults were enrolled in this study and denaturing high performance liquid chromatography (PCR-DHPLC) was carried out to verify the mutation excluding polymorphism sites found in this family. Changes in protein structure and function caused by the mutated coding sequence was analyzed by SWISS-MODEL software. RESULT: The proband had pigmented mucocutaneous lesions and multiple hamartomatous polyps in the gastrointestinal tract. There was no fragment deletion of LKB1 gene detected by MLPA. Among PJS family and 250 healthy adults, germline mutation c. 924G > C of LKB1 which cause Trp308Cys in protein sequence was identified only in the proband and another affected member. LKB1 protein activity could be reduced due to changes in LKB1 protein conformation structure by Trp308Cys. CONCLUSION: Peutz-Jeghers syndrome (PJS) is an autosomal dominant disorder characterised by mucocutaneous pigmentation, multiple gastrointestinal hamartomatous polyps and heredofamilial nature. Gene identification and mutagen screening of LKB1 gene in all PJS patients and first degree relatives will contribute to a definite diagnosis and improve the life span of the family.

Hypermethylation of CpG islands is more prevalent than hypomethylation across the entire genome in breast carcinogenesis.

This study aimed to establish a high-throughput, genome-wide and non-gene-specific approach to assess the methylation status of multiple CpG islands in parallel and employ it to detect the CpG island methylation profiling alterations in breast carcinogenesis. We used methylation-sensitive restriction fingerprint (MSRF) to screen the permutations of primers that could detect varied and specific methylation profiling in genomic DNA isolated from four different cell lines. Five permutations of nine arbitrary primers were determined for the following experiments based on the above test. We then examined the methylation profiling alterations of CpG islands in 31 breast cancer tissue samples relative to their adjacent non-neoplastic tissues with modified MSRF that replaced silver staining with denatured high-performance liquid chromatography for size fraction. We found that two pairs of primers could reveal specific alterations of CpG methylation in the examined tissues, and 83.9% (26/31) of breast cancer tissues exhibited specific CpG island methylation profiling relative to their adjacent non-neoplastic tissues. Size fraction analysis revealed that hypermethylation of CpG islands was responsible for the aberrant methylation profiling in breast cancer tissues. Our work not only established a relative high-throughput, genome-wide and economic method to detect methylation alterations of CpG island profiling, but also revealed that hypermethylation of CpG islands was more prevalent than hypomethylation across the entire genome in our examined cancer tissues. The methylation profiling alterations revealed by two primer pairs used in the present study might be a novel marker for breast cancer.

Plasma post-operative miR-21 expression in the prognosis of gastric cancers.

Tumor-associated microRNAs have been detected in serum or plasma, but whether plasma microRNA-21 (miR-21) could be a potential circulating biomarker for gastric cancer (GC) prognosis in Chinese is still uncertain. Real-time quantitative reverse transcription PCR (qRT-PCR) was employed in this study to compare the relative expression of miR-21 between pre-operative and post-operative paired plasmas from 42 patients with primary GCs. The results showed that the expression levels of miR-21 in the post-operative plasmas were significantly reduced by an average of 18.2 times in all patients when compared to the pre-operative plasmas, and by 22.1 times in the subgroup of patients without family history, while only 1.76 times in the subgroup of patients with a family history. With respect of clinicopathological characteristics, the plasma miR-21 expression was highly associated with differentiation degree and lymph node metastasis rate. The results suggested plasma miR-21 could be a novel potential biomarker for GC prognosis and evaluation of surgery outcomes, especially in patients without a family history.