7q11.23 duplication syndrome, a condition that can cause a variety of neurological and behavioral problems as well as other abnormalities, results from an extra copy of a region on the long (q) arm of chromosome 7. This region is called the WilliamsBeuren syndrome critical region (WBSCR) because its deletion causes a different disorder called Williams syndrome (described below), also known as Williams-Beuren syndrome. The region, which is 1.5 to 1.8 million DNA base pairs (Mb) in length, includes 26 to 28 genes.
The expanding role of genetics in almost every clinical condition is associated with the increasing development of new genetic and molecular test, and implementation of these tests is becoming well integrated into medical practice. Therefore, primary care providers, family doctors, pediatricians, and other specialists involved in the care of patients and families affected by genetic conditions will be largely concerned with both genetic tests and genetic counseling. That process may be considered in several stages: collecting genetic information and pedigree drawing; making or validating the diagnosis; estimating occurrence and recurrence risk; communicating clinical information; and supporting the family to reach a decision and take appropriate action. However, the term "genetic counseling" is often used to describe the entire approach to patients and families with genetic conditions, sometimes being restricted to the communication and psychotherapeutic process. Consequently, the separation of clinical from supportive process had an important role in most definitions of genetic counseling. Should all those aspects be considered parts of a single process? This is the main question that will be discussed hereafter, under the hypothesis that the synthesis of all those steps should be required to approach any genetic conditions. In that view, rethinking of genetic counseling from a medical point of view should be seen as an important subject for discussion, and might contribute to bring together clinical and nonmedical aspects.
A new method to detect mutations based on the serial analysis of gene expression (SAGE) technique, ligation-mediated (LM) PCR, and recombinant nuclease CEL I named LM-SAGE assay is reported in the present study. Mismatched DNA heteroduplexes formed from wild-type and mutant DNA are fragmented with CEL I nuclease at the mutant site to produce a double-strand fragment with an overhanging base at the 3'-end. The fragment is ligated to a linker, and digested with MmeI and then ligated to another linker. PCR is performed to amplify the ligation products, and NlaIII is used to release 17-bp tags containing mutation sites followed by purification, concatemerization, cloning, and sequencing. The locations of mutations can be identified from the homology analysis of tags. This new LM-SAGE assay can detect both known and unknown mutations with a sensitivity of 1:50 (mutant:wild-type DNA ratio) in 2.4 x 10(6) copies starting DNA sample. Our results show that this method could be used as a potentially high-throughput assay for mutation detection, particularly for the discovery of unknown mutations in genomic DNA.
We investigated the hypothesis that coinheritance of the common A(TA)(n)TAA promoter mutation at the UGT1A1 locus associated with Gilbert syndrome is a risk factor for gallstone formation in a homogeneous adult population, by conducting a case-control study that included 198 adult patients with cholelithiasis and 152 healthy controls both of Greek origin. Three genotypes were found: 7/7 (17.8% in controls and 23.3% in patients), 6/7 (33.5% in controls and 46.5% in patients), and normal homozygous 6/6 (48.7% in controls and 30.3% in patients). The Gilbert UGT1A1 genotypes 6/7 and 7/7 show significant association (odds ratio 2.225, 95% confidence interval 1.373-3.605, p = 0.001, and odds ratio 2.101, 95% confidence interval 1.171-3.770, p = 0.013, respectively) with cholelithiasis risk. This association supports the theory that genetic factors are responsible for a fraction of symptomatic gallstone disease; however, further studies are required in different ethnic groups to fully elucidate the involvement of Gilbert syndrome in gallstone disease.
Aims: To verify whether dystrophin gene mutations among Chinese patients feature different types and frequencies from other populations. Methods: Multiplex ligation-dependent probe amplification (MLPA) in combination with multiplex PCR (mPCR) and/or short tandem repeat (STR)-based linkage analysis were applied in a large series of Chinese families affected with Duchenne muscular dystrophy (DMD) or Becker muscular dystrophy (BMD). There were a total of 19 cases seeking prenatal diagnosis during their second pregnancies. Results: Of the 59 family trios (51 with DMD and 8 with BMD), 40 were found to have carried various mutations of the dystrophin gene. In addition to deletions and duplications within the mutational hotspots identified by both methods, 10 mutations missed by mPCR were detected by MLPA, among which at least 3 were of rare types. Combined MLPA and linkage analysis also achieved prenatal diagnoses in all of the 19 amniocentesis samples. Conclusions: Mutations of dystrophin gene among Chinese patients showed a diverse spectrum, with similarity to as well as discrepancies from other populations. For the comprehensive coverage of all exons of the dystrophin gene, MLPA should be the method of choice for initial screening of DMD/BMD patients. When combined with STR-based analysis, it can achieve diagnosis in as much as 70-80% of all referred cases.
Psychiatric genetic research brings on the possibility of psychiatric genetic testing. The optimal and responsible utilization of genetic testing depends on knowledge of the potential consumers' attitudes and expectations regarding testing. The aim of this study was to assess potential consumers' attitudes and expectations toward psychiatric genetics and factors influencing their intentions to test. A questionnaire constructed to assess attitudes and intentions toward psychiatric genetic testing was mailed or given in person to individuals participating in different genetic studies aiming at identifying genes predisposing for mental illness. A total of 397 persons diagnosed with major depression, bipolar disorder, schizophrenia, or anxiety disorder participated in the survey. A large majority of the sample expressed an intention for themselves and their children to participate in psychiatric genetic testing. Support for prenatal testing was considerably less strong. A large minority expressed intention to test regardless of treatment possibilities. Intentions to test were positively associated with being a parent, trust in researchers, and expecting to feel better prepared for fighting the disorder when knowing of the presence of risk genes. Intentions were negatively associated with the fear of psychiatric genetic research bringing on too many difficult choices and fearing not to be able to cope with the results of a psychiatric genetic test. These results indicate that psychiatric genetic testing is not just perceived as a way to better treatment. Other expectations may motivate testing even though the clinical validity of the test is poor.
Rett syndrome (RTT), an X-linked dominant neurodevelopmental disorder, is caused mainly by de novo mutations in the methyl-CpG-binding protein 2 gene (MECP2). Although more than 200 different MECP2 mutations have been identified throughout the gene, 7 of those (p.R133C, p.T158M, p.R168X, p.R255X, p.R270X, p.R294X, and p.R306C) account for up to two-thirds of pathogenic mutations in RTT patients. A rapid and efficient screening strategy for these mutations can be used as a preliminary step for genetic diagnosis of RTT. The current protocols used for this purpose are of high cost and require special equipment. We have designed a simpler multiplex amplification refractory mutation system (ARMS)-PCR strategy that allows identification of these common MECP2 mutant alleles in four PCR reactions. The assay was tested in 14 RTT patients who were previously genotyped using PCR-restriction fragment length polymorphism and DNA sequencing. A complete concordance was observed between the results of the two methods. The multiplex ARMS-PCR does not require any special equipment, and it provides rapid, reproducible, and cost-effective detection of common MECP2 mutations. The assay can be carried out efficiently in a standard molecular genetics laboratory and suitable as a preliminary screen for all patients with RTT diagnosis.
Aim: To review the psychosocial benefits and harms of DNA testing for HFE-related hereditary hemochromatosis (HH) in at-risk individuals. Background: HH is a common genetic disease in people of European descent. DNA-based predisposition testing is used for diagnosis or in the context of family testing, but there are concerns about potential psychosocial consequences. Methods: Fifteen electronic databases (including Medline and Cochrane) were searched from inception to April 2007 to identify any quantitative or qualitative primary research that considered DNA testing of individuals considered at-risk of HH and reported psychosocial outcomes. Inclusion criteria, data extraction, and quality assessment were undertaken by standard methodology. Results: Three observational studies met the inclusion criteria of the review; each had methodological limitations. On receipt of test results, anxiety levels fell or were unchanged; general health-related quality-of-life outcomes improved in some aspects, or were unchanged with respect to pretest result values. Outcomes were not reported separately for those referred for diagnosis and those with family history of HH. Results suggest that genetic testing for HH in at-risk individuals is accompanied by few negative psychosocial outcomes. Conclusion: The evidence on the psychosocial aspects of DNA testing for HH in at-risk individuals is limited. Further research might be required if other factors influencing the natural history of the disease phenotype are identified.
Cystic fibrosis carrier testing (CFCT) is among the first of the DNA tests offered prenatally in primary care settings. This paper from a descriptive qualitative study describes the influence of pregnancy in CFCT decisions by women receiving community-based prenatal care. Twenty-seven women receiving prenatal care in Midwestern U. S. primary care clinics completed semistructured interviews. Audiotaped interviews were analyzed using content analysis. Participants described decision-making influences and strategies from the perspective of "being pregnant." Patterns of attitudes and beliefs include (1) dealing with emotions, (2) pregnancy is natural, and (3) thinking about the baby. Strategies in the decision-making process included (1) reducing stress, (2) choosing what is relevant, (3) doing everything right, (4) wanting to be prepared, (5) delaying information, and (6) trusting God. While other factors were mentioned by some women, major themes reflect the influence of currently being pregnant on the decision-making process. These findings suggest that pregnancy is a powerful influence on the decision-making process and may not be the optimal time to make fully informed decisions regarding genetic carrier testing. Further understanding of factors influencing the genetic testing decision-making process is needed. Offering CFCT prior to conception is advocated.
Aims: The purpose of this study was to investigate the association of methylation in the promoter regions of adenomatous polyposis coli (APC) and O-6-methylguanine-DNA methyltransferase (MGMT) and the survival of Taiwanese colorectal cancer (CRC) subjects who received 5-fluorouracil (5-FU) adjuvant chemotherapy. Results: DNA isolated from tumor tissue of 117 CRC subjects was analyzed for the existence of methylation in the promoter regions of APC and MGMT by methylation-specific PCR. Various characteristics of the 117 subjects were recorded and used in the Cox proportional-hazard model analyses. Methylation in the promoter region is 62.4% (73/117) for APC and 60.7% (71/117) for MGMT in our CRC patients. Subjects presenting methylation in the APC promoter demonstrate significantly lower hazards for all causes of death (hazard ratios = 0.378, p = 0.011) or CRC deaths (hazard ratios = 0.426, p = 0.039). However, no significant correlation is found between the methylation of MGMT promoter and the prognosis of CRC subjects. In addition, no interaction between 5-FU adjuvant chemotherapy and methylation of the two genes are observed. Conclusions: Methylation in the APC promoter may serve as a predictor for the prognosis of Taiwanese CRC patients.
Inflammatory bowel disease (IBD) with ulcerative colitis (UC) and Crohn's disease (CD) as the most common forms is an inflammation of the gastrointestinal tract. Familial Mediterranean fever (FMF) is another inflammatory disease as well. In the current study we studied FMF gene mutations in 47 patients with IBD and 25 healthy individuals to investigate the effects of these mutations on the clinical status of IBD. Twelve mutations were analyzed by reverse hybridization after multiplex PCR amplification of DNA samples. We did not find an association between FMF gene mutations and IBD phenotypic characteristics. However, in patients without Mediterranean fever (MEFV) mutations, extraintestinal disease frequencies were higher (p < 0.05). IBD has a genetic basis with multiple genes probably playing a role via several pathways during disease progression. Studying other genes interacting with FMF gene in a larger group of patients will add to the knowledge of disease pathogenesis.
We describe two Chilean patients with dysferlinopathy, a 32-year-old man with Miyoshi's distal myopathy and a 29-year-old woman with a proximodistal phenotype. Absence of dysferlin in frozen muscle biopsy allowed diagnostic confirmation. In these two patients, two mutations not previously identified in other populations were found: a homozygous c.1948delC (p. Leu650TyrfsX6) was found in the male patient; the heterozygous mutation c.1276G>A (p.Gly426Arg) was found in the female patient in association with the previously reported c.2858dupT (p.Phe954ValfsX2). To our knowledge, this is the first time that mutations in DYSF are identified in native Chileans. Our findings suggest the possibility that mutations in the DYSF gene were present in the Native American population before colonization.
Introduction and Aims: For women who carry BRCA mutations, risk-reducing surgeries are an option to decrease breast and ovarian cancer risk. This study aims to determine the uptake, time course, and predictors of risk-reducing mastectomy (RRM) and risk-reducing salpingo-oophorectomy (RRSO) in BRCA carriers. Results: In 272 female carriers, followed for a median of 3.7 years, 23% of those eligible chose RRM, and 51% percent chose RRSO. Among BRCA carriers who chose these procedures, median time to both RRM and RRSO was approximately 4 months after learning of BRCA-positive results. Predictors of RRM were as follows: age below 60 years (hazard ratio 1.8, p = 0.04), prior breast cancer (hazard ratio 2.4, p = 0.0004), and RRSO ( hazard ratio 7.2, p < 0.0001). Predictors of RRSO were as follows: age below 60 years (hazard ratio 3.6, p = 0.006), prior breast cancer (hazard ratio 1.8, p = 0.002), and RRM (hazard ratio 5.4, p < 0.0001). Conclusions: Many women who undergo BRCA testing use these results to make clinical decisions; those who choose risk-reducing surgeries typically do so within months of receiving BRCA-positive results. Predictors of risk-reducing surgery uptake include the following: age below 60 years, prior breast cancer, and utilization of another risk-reducing surgery. Future research directions include examining other preventive and screening options in BRCA carriers as well as studying motivations for choosing or declining risk-reducing surgeries.
The aim of this study was to assess the prevalence of several polymorphisms in genes that are involved in several pathways such as hemostasis, fibrinolysis, platelet membrane receptor activity, endothelial integrity and function, lipid metabolism, and regulation of blood pressure in healthy subjects of Greek origin. Most of these polymorphisms are mainly associated with conditions such as venous thromboembolism and atherothrombosis, and their prevalence has not been studied yet in Greece. We tested 140 healthy individuals for factor V (FV)1691G/A, FV4070G/A, FII 20210G/A, factor XIII (FXIII) exon 2G/T, fibrinogen beta-455G/A, plasminogen activator inhibitor-1 (PAI-1)-675 4G/5G, human platelet antigens 1 (HPA1) a/b, apolipoprotein B (ApoB) 10708 G/A, apolipoprotein E (ApoE) E2, E3, and E4, angiotensin-converting enzyme (ACE) D/I, 5,10 methylenetetrahydrofolate reductase (MTHFR) 677C/T, and MTHFR 1298A/C polymorphisms using a PCR and reverse hybridization technique that detects all of them simultaneously. The allele frequencies observed are in accordance with those reported in other Caucasian populations and almost identical to those of East Mediterranean populations. This first report from Greece may serve as a baseline for planning further investigations of these polymorphisms in association with several clinical entities and for launching guidelines for patient testing of various disease settings in this population.
The association of the gene encoding calpain 10 with type 2 diabetes mellitus (T2DM) has been reported. In this study we aimed to evaluate the association of SNP-19,-44, and -63 polymorphisms of calpain 10 with type 2 diabetes and diabetic-related conditions, such as diabetic retinopathy, nephropathy, and neuropathy in a Turkish population. The study group included 202 patients (133 female and 69 male) with T2DM, while the control group included 80 nondiabetic people (44 female and 36 male). Genotyping was done by the polymerase chain reaction and restriction fragment length polymorphism method. Calpain 10 SNP-44 TC genotype was found to be significantly frequent in type 2 diabetic patients with respect to the control group (p < 0.01). Body mass index (BMI) was found to be significantly high in TC genotype with type 2 diabetic patients (p < 0.05). SNP-44 T allele frequency was found to be lower in type 2 diabetic patients compared with the controls (p < 0.01). We conclude that the calpain 10 SNP-44 gene polymorphism may be accepted as a risk factor in the development of T2DM and elevated BMI in type 2 diabetic patients in a Turkish population.
Background: Familial Mediterranean fever (FMF) is an autosomal recessive disorder, caused by mutations in MEFV gene that encodes pyrin protein. In this study, we analyzed the most common five mutations in MEFV gene of 202 patients who were diagnosed formerly as FMF according to Tel-Hashomer criteria. The results of genetical analysis, clinical symptoms, and demographical aspects of those patients were evaluated retrospectively. Methods and Results: Between the dates of February 2005 and March 2007, we analyzed five common MEFV gene mutations, which were M680I, M694V, M694I, V726A, and E148Q, in 202 patients by the PCR-ELISA method in our medical genetics laboratory. The most frequent mutation detected in our patients was M694V, and other mutations according to frequency were E148Q, M680I, V726A, and M694I. The detected mutations were homozygous in 45 of the patients (22.2%), heterozygous in 103 (51%), compound heterozygous in 52 (25.8%), and in 2 patients (1%) complex alleles were defined. The most common symptom was abdominal pain (80.4%) and other symptoms, respectively, were fever (57.8%), arthralgia (36.7%), chest pain (4.5%), and skin rash (2%). Amyloidosis was present in seven patients, and five of them had M694V mutation (homozygous), one of them had E148Q (heterozygous) mutation, and the other one had M694V/M694I mutation. Conclusion: In our patients, we defined 21 different genotypes of MEFV gene and the most common mutation was M694V. The most common symptoms were abdominal pain and fever. We detected significant correlation between the M694V, E148Q, and V726A mutations and clinical findings.
Commercialization of genetic technologies is expanding the horizons for the marketing and sales of genetic tests direct-to-consumers (DTCs). This study assesses the information provision and access requirements that are in place for genetic tests that are being advertised DTC over the Internet. Sets of key words specific to DTC genetic testing were entered into popular Internet search engines to generate a list of 24 companies engaging in DTC advertising. Company requirements for physician mediation, genetic counseling arrangements, and information provision were coded to develop categories for quantitative analysis within each variable. Results showed that companies offering risk assessment and diagnostic testing were most likely to require that testing be mediated by a clinician, and to recommend physician-arranged counseling. Companies offering enhancement testing were less likely to require physician mediation of services and more likely to provide long-distance genetic counseling. DTC advertisements often provided information on disease etiology; this was most common in the case of multifactorial diseases. The majority of companies cited outside sources to support the validity of claims about clinical utility of the tests being advertised; companies offering risk assessment tests most frequently cited all information sources. DTC advertising for genetic tests that lack independent professional oversight raises troubling questions about appropriate use and interpretation of these tests by consumers and carries implications for the standards of patient care. These implications are discussed in the context of a public healthcare system.
Idiopathic congenital nystagmus (ICN) is a common oculomotor disorder characterized by bilateral involuntary, periodic, and predominantly ocular oscillations. X-linked ICN (XLICN) with incomplete penetrance in females is the most common inheritance form, and FERM domain containing (FRMD7) mutation is the major reason for XLICN families. To date, 39 FRMD7 mutations have been identified, and 50% of the XLICN pedigrees have yielded FRMD7 mutations in the Western population. In this study, we identified a novel frameshift mutation (c.1274-1275delTG) in the FRMD7 gene in six XLICN pedigrees. Incorporated with data reported from other two Chinese groups, approximately 47% XLICN pedigrees were caused by the FRMD7 mutation in China. Therefore, this study showed that mutation analysis of the FRMD7 gene had diagnostic value not only in the Western population but also in one of the biggest Eastern populations, Chinese XLICN families. In addition, the results indicated the type of FRMD7 mutation associated with the penetrance of female carriers of XLICN.
The most common genetic causes of spermatogenic failure are sex chromosomal abnormalities (most frequently Klinefelter's syndrome) and deletions of the azoospermia factor (AZF) regions (AZFa, AZFb, and AZFc) of the Y chromosome. Several studies have proposed that partial AZFc deletions/duplications may be a risk factor for spermatogenic impairment. We describe a multiplex quantitative fluorescent-polymerase chain reaction (QFPCR) method that allows simultaneous detection of these genetic causes and risk factors of male infertility. The 11-plex QF-PCR permitted the amplification of the amelogenin gene, four polymorphic X-specific short tandem repeat (STR) markers (XHPRT, DXS6803, DXS981, and exon 1 of the androgen receptor gene), nonpolymorphic Y-specific marker (SRY gene), polymorphic Y-specific STR marker (DYS448), and coamplification of DAZ/DAZL, MYPT2Y/MYPT2, and two CDY2/CDY1 fragments that allow for determination of the DAZ, MYPT2Y, and CDY gene copy number. A total of 357 DNA samples from infertile/subfertile men (n = 205) and fertile controls (n = 152) was studied. We detected 14 infertile males with sex chromosome aneuploidy (10 with Klinefelter's syndrome, 2 XX, and 2 XYY males). All previously detected AZF deletions, that is, AZFc (n8), AZFb (n1), AZFb + c (n1), gr/gr (n11), gr/gr with b2/b4 duplication (n3), and b2/b3 (n5), gave a specific pattern with the 11-plex QF-PCR. In addition, 32 DNA samples showed a pattern consistent with presence of gr/gr or b2/b4 and 4 with b2/b3 duplication. We conclude that multiplex QF-PCR is a rapid, simple, reliable, and inexpensive method that can be used as a first-step genetic analysis in infertile/subfertile patients.
To improve the differentiation of thalassemia intermedia from other hemoglobinopathies in Iran, four known genetic mechanisms-XmnI (G)gamma polymorphism, inheritance of mild and silent beta-thalassemia alleles, delta beta deletion, and coinheritance of alpha- and beta-thalassemia-were investigated in 52 Iranian individuals suspected to have thalassemia intermedia based on clinical and hematological characteristics. Beta-globin mutations were studied using a reverse-hybridization assay and sequencing of the total beta-globin gene. The XmnI (G)gamma polymorphism, the Sicilian delta beta deletion, and four alpha-globin mutations (-a(3.7), -a(4.2), -(MED), aaa(anti-3.7)) were studied using PCR-based techniques. The inheritance of the XmnI (G)gamma polymorphism with severe beta-thalassemia alleles in the homozygous or compound heterozygous state was the predominant mechanism observed in 27 individuals (55.3%). In five cases, this status overlapped with the -a(3.7)/aa genotype. The second most frequent cause for thalassemia intermedia (14.8%) was the inheritance of mild beta-thalassemia alleles, including IVS-I-6 (T > C), -88 (C > A), and + 113 (A > G). In three subjects (4.3%) the Sicilian delta beta deletion was identified. HbS in association with beta-zero-thalassemia was found in three patients with thalassemia intermedia phenotype. In 11 cases (21.3%) no causative genetic alteration could be identified. Our results reflect the diversity underlying thalassemia intermedia, and the limitations of the applied clinical, hematological, and molecular approaches for correct diagnosis. Some of the unresolved cases will offer an opportunity to discover additional molecular mechanisms leading to thalassemia intermedia.
