Preimplantation diagnosis for neurofibromatosis

Preimplantation genetic diagnosis (PGD) has recently been performed for inherited cancer predisposition determined by p53 tumour suppressor gene mutations, suggesting the usefulness of PGD for late onset disorders with genetic predisposition, including those caused by the germline mutations of other tumour suppressor genes. Here PGD was performed for two couples, one at risk for producing a child with maternally derived neurofibromatosis type I (NF1), and the other with paternally derived neurofibromatosis type II (NF2). The procedure involved a standard IVF protocol, combined with testing of oocytes or embryos prior to their transfer back to the patients. Maternal mutation Trp-->Ter (TGG-->TGA) in exon 29 of the NF1 gene was tested by sequential PCR analysis of the first and second polar bodies, and paternal L141P mutation in exon 4 of the NF2 gene by embryo biopsy at the cleavage stage. In both cases, multiplex nested PCR was applied, involving NF1 and NF2 mutation analysis simultaneously with the 3 and 2 linked markers, respectively. Of 57 oocytes tested in four PGD cycles for NF1 mutation, 26 mutation-free oocytes were detected, from which eight were preselected for transfer, two in each cycle. These produced two clinical pregnancies, one confirmed to be mutation free by chorionic villus sampling but ending in a stillbirth, and the other still ongoing. Of 18 embryos analysed in a cycle performed for NF2 mutation, eight mutation-free embryos were detected, three of which were transferred back to the patient, resulting in a singleton pregnancy and the birth of a mutation-free child. This suggests that PGD is a useful approach for avoiding the birth of children with inherited cancer predisposition, determined by NF1 and NF2 gene mutations.     

Late onset adrenal hyperplasia: mutation at codon 282 of the functional 21-hydroxylase gene is not ubiquitous

Ten patients affected with 21-hydroxylase (21-OH) deficient late-onset adrenal hyperplasia were studied to determine the prevalence of a mutation at codon 281 of the functional 21-OH gene (CYP21B) that results in a valine to leucine amino acid shift. This mutation has been reported in eight unrelated late-onset adrenal hyperplasia patients of Ashkenazi Jewish descent possessing the human leukocyte antigen-B14,DR1 haplotype. Normally, there are two 21-OH genes; a pseudogene (CYP21A) and a functional gene (CYP21B). The aberrant codon 281 sequence is normally present only in CYP21A. In all of our late-onset adrenal hyperplasia patients, hybridization of an oligonucleotide probe specific for this mutation was demonstrated to CYP21A but not to CYP21B. The mutation at codon 281 of CYP21B does not appear to be a ubiquitous genetic marker for 21-OH deficient late-onset adrenal hyperplasia, suggesting that this disorder may demonstrate the same molecular heterogeneity as congenital adrenal hyperplasia.     

Linkage and mutation analysis in two Taiwanese families with long QT syndrome.

Long QT syndrome (LQT) is a cardiovascular disorder causing syncope and sudden death from arrhythmias. Mutations in KCNQ1, KCNH2, KCNE1, KCNE2, and SCN5A genes encoding cardiac potassium and sodium ion channels cause LQT. Two Taiwanese LQT families were screened for mutations in these ion channel genes. In family H87, the diagnosis was made in the 25-year-old female proband and six family members based on recurrent syncope and/or a prolonged QT interval. Genotyping revealed a novel nonsense mutation, R744X (C to T transition in codon 744), in the KCNH2 potassium channel gene, resulting in truncation of the putative cyclic nucleotide-binding domain and C-terminal region of the HERG K(+)-channel in all affected family members. The mutation was confirmed by DdeI endonuclease digestion of the DNA from each family member. The 26-year-old female proband in family L89 developed repeated syncope with QTc of 0.61 seconds. After linkage and mutation analysis, the syndrome in this family was associated with a novel KCNQ1 missense mutation, T309I, causing the substitution of a threonine residue at position 309, in the pore region of the KvLQT1 K(+)-channel, with an isoleucine. By Tsp45I restriction analysis, the mutation was noted in the proband and the proband's asymptomatic brother, but was not detected in 100 unrelated normal individuals. Identification of a mutation has clinical implications for presymptomatic diagnosis and therapy.     

LDLR and ApoB are major genetic causes of autosomal dominant hypercholesterolemia in a Taiwanese population.

BACKGROUND/PURPOSE: Autosomal dominant hypercholesterolemia (ADH) is an autosomal dominant inherited disease characterized by an increase in low-density lipoprotein cholesterol levels and premature coronary heart disease, which can be caused by mutations in genes encoding the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB) and proprotein convertase subtilisin/kexin type 9 (PCSK9). There is scant information with regard to the role played by each gene in the Taiwanese ADH population, especially the newly discovered PCSK9 gene. METHODS: We used coupling heteroduplex analysis based on a denaturing high performance liquid chromatography system and DNA sequencing to screen for the LDLR gene, APOB gene and PCSK9 gene in 87 ADH cases recruited from 30 unrelated Taiwanese families. RESULTS: We did not find any mutation-causing variant of the PCSK9 gene in our cases and thus excluded PCSK9 as the major culprit mutation in these families. On the other hand, we identified six previously reported LDLR gene mutations (C107Y, D69N, R385W, W462X, G170X, V408M), two novel LDLR gene mutations (FsG631 and splice junction mutation of intron 10), and one known mutation (R3500W) and one novel missense mutation (T3540M) in the APOB gene that were present in 55 members from 18 ADH families (60%). R3500W, rather than R3500Q, could be the principle mutation responsible for familial defective apolipoprotein B in Taiwanese. CONCLUSION: The results of our study reveal a characteristic mutation pattern of ADH in Taiwan, mainly in the LDLR and APOB genes. However, PCSK9 gene mutation may not be a major cause of ADH in our study population.     

Primary habitual abortions are associated with high frequency of factor V Leiden mutation

OBJECTIVE: To analyze the prevalence of the mutation G1691A in factor V gene (Leiden mutation), of mutation C677T in the methylenetetrahydrofolate reductase (MTHFR) gene, and of polymorphism in G20210A in the prothrombin gene in women with recurrent abortions; further, to identify a subgroup at higher risk of being carriers of these mutations. DESIGN: Prospective case control evaluation. SETTING: University clinic. PATIENT(S): Eighty-four women with 3 or more consecutive miscarriages were compared with 69 controls. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Polymerase chain reactions were performed to identify the mutations G1691A in factor V and C677T in MTHFR genes and the polymorphism G20210A in the prothrombin gene. RESULT(S): In women with primary habitual abortions, 27.8% carried the Leiden mutation. No difference was observed in the prevalence of mutation C677T in the MTHFR gene or in polymorphism G20210A in the prothrombin gene. CONCLUSION(S): The Leiden mutation may play a considerable role for women having primary recurrent abortions.     

Hearing-loss-associated gene detection in neonatal intensive care unit

Objective: To investigate the frequency and mutation spectrum of hearing loss-associated gene mutation in Neonatal Intensive Care Unit (NICU).

Methods: Neonates (n=2305) admitted to NICU were enrolled in this study. Nine prominent hearing loss-associated genes, GJB2 (35 del G, 176 del 16,235 del C, 299 del AT), GJB3 (538 C?>?T), SLC26A4 (IVS7-2A?>?G, 2168 A?>?G) and mtDNA 12S rRNA(1555 A?>?G, 1494 C?>?T), were detected.

Result: There were 73 cases hearing-loss-associated gene mutation among 2305 cases, the mutation frequency was 3.1%, with 40 cases GJB2 (235del C) mutation (54.8%), 6 cases GJB2 (299 del AT) mutation (8.2%), 21 cases SLC26A4 (IVS 7-2 A?>?G) mutation (28.7%), 4 cases SLC26A4 (2168 A?>?G) mutation (5.5%), 2 cases of GJB2 (235del C) combined SLC26A4 (IVS 7-2 A?>?G, 2168 A?>?G) mutation (2.8%). Among 73 gene mutation cases, preterm neonates presented in 18 cases, accounting for 24.7% (18/73); hyperbilirubinemia in 13 cases, accounting for 17.8% (13/73); Torch Syndrome in 15 cases, with 12 cases CMV, 2 cases rubella, 1 case toxoplasm, respectively, totally accounting for 20.54% (15/73); neonatal pneumonia in 12 cases, accounting for 16.4% (12/73); birth asphyxia in 5 cases, accounting for 6.9% (5/73); sepsis in 5 cases, accounting for 6.9% (5/73); others in 5 cases, accounting for 6.8% (5/73) .

Conclusions: The frequency of hearing loss-associated gene mutation was higher in NICU.There were hearing loss-associated gene mutations in the NICU, suggesting this mutation may complicate with perinatal high-risk factors.     

Risk of endometrial carcinoma associated with BRCA mutation

OBJECTIVE: Inherited mutations in the BRCA1 or BRCA2 genes are associated with a greatly increased lifetime risk of breast and ovarian cancers and a modestly increased risk of several other cancer types. Several case reports of endometrial carcinoma in women with a BRCA mutation have led to speculation regarding the effect of these genes on the risk of endometrial cancer. The purpose of this study was to test the hypothesis that germline mutation of a BRCA gene is associated with an increased risk of endometrial carcinoma. METHODS: A retrospective cohort of 199 consecutive Ashkenazi Jewish patients with endometrial carcinoma was identified from a 12-year period at this institution. All were genotyped for the three BRCA founder mutations (185delAG and 5382insC in BRCA1 and 6174delT in BRCA2) that exist in this population, and the case frequency was compared to the known population frequency of these mutations. Additionally, endometrial carcinomas occurring in patients with BRCA mutations were assessed for somatic loss of the wild-type BRCA allele. RESULTS: Germline BRCA mutations were identified in 3 (1 in BRCA1 and two in BRCA2) of 199 (1.5%) patients, compared to a frequency of 2.0% in this population generally. A relative risk of endometrial carcinoma associated with BRCA mutation, as estimated by the odds ratio, was calculated as 0.75 (95% CI = 0.24--2.34; P = 0.6). Loss of the wild-type BRCA allele was observed in two of three tumors associated with a BRCA mutation. CONCLUSIONS: For individuals with a germline BRCA mutation, the lifetime risk of endometrial carcinoma is not increased.     

DNA microarray analysis of gene expression markers of endometriosis.

OBJECTIVE: To use DNA microarray technology to examine differential gene expression in uterine endometrium versus endometriosis implants. DESIGN: Pilot study. SETTING: Volunteers in an academic research environment. PATIENT(S): Premenopausal women scheduled for surgery for suspected endometriosis. INTERVENTION(S): Surgical excision of endometriosis tissue and uterine endometrial biopsy. MAIN OUTCOME MEASURE(S): Gene expression. RESULT(S): The expression of eight genes from a total of 4,133 genes on the DNA microarray was increased in endometriosis implants compared with uterine endometrium. The eight genes were beta-actin, alpha-2 actin, vimentin, 40S ribosomal protein S23, Ig-lambda light chain, Ig germline H chain G-E-A region gamma-2 constant region gene, major histocompatibility complex class 1,C, and complement component 1 S subcomponent. CONCLUSION(S): The data demonstrate that the DNA microarray is an effective tool for the identification of differentially expressed genes between uterine and ectopic endometrium; further study of the genes identified herein will expand our understanding of the nature of endometriosis and assist in the eventual development of new treatments for endometriosis.     

Risk of thrombophilia in carriers of thrombophilic genetic factors in unsuccessful assisted reproduction

The aim of this study was to evaluate an association of carrier status of common inherited thrombophilic genetic mutations and implantation failure after assisted reproduction (ART): IVF and ICSI. Sixty seven women with failure of embryo implantation and ninety six controls--women without obstetric complication were investigated for carriage of factor V Leiden (FVL), G20210A prothrombin gene mutation, genetic variant C677T in methylentetrahydrofolate reductase gene (MTHFR) and polymorphism A2 in platelet glycoprotein IIb/IIIa (GIPr IIb/IIIa). A significantly higher prevalence of polymorphism A2 in GIPr IIb/IIIa was found in women with implantation failure in ART compared to controls (respectively 26.1% and 12.5%; OR: 2.571, 95% CI: 1.066-6.258, p = 0.033). A higher but not significant prevalence of G20210A prothrombin gene mutation carriage was found inpatients compared to controls (respectively 5.8% and 3.13%, OR: 1.968, 95% CI 0.356-11.539). The carriage of FVL was a little but not significantly higher in controls. The carriage of genetic variant C677T in MTHFR was the same in both groups. These data suggest that polymorphism A2 in GIPr IIb/IIIa and G20210A prothrombin gene mutation could be play a role in the etiology of IVF failures and the carriers of GIPr IIb/IIIa A1/A2 and G20210A prothrombin gene mutation are at higher risk of implantation failure and not successful ART outcome. The carriage of these two genetic defects should be investigated in women undergoing IVF and the antithrombotic or anticoagulant prophylaxis should be indicated for carriers of these two factors.     

Factor V Leiden and factor II G20210A in preeclampsia and HELLP syndrome

BACKGROUND: The association of factor V and factor II mutations with preeclampsia and hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome, and a possible role of the two thrombophilic mutations in the pathogenesis of the diseases have been previously investigated. The results, however, are still inconclusive and contradictory. METHODS: A case-control study was performed over an interval of 24 months, on 111 subjects with preeclampsia and 111 normal pregnant women matched for age and parity, without previous thromboembolic disorders. The subjects were tested for the mutation A1691G in the factor V gene (R506Q or Leiden mutation) and the mutation A20210G in the factor II (prothrombin) gene. The Student's t-test and the chi2-test were applied when appropriate, and odds ratios and 95% confidence intervals were calculated. RESULTS: Fourteen patients with preeclampsia (12.6%) had at least one of the two mutations, as compared with six controls (5.4%). Factor V Leiden was found in eight patients with preeclampsia (7.2%) and in five controls (4.5%). Factor II G20210A was detected in eight preeclamptic women (7.2%) and in one normal pregnant woman (0.9%)(p = 0.041). In the subgroup of 32 preeclamptic subjects with HELLP syndrome, factor V Leiden was found in three patients (9.3%) and factor II G20210A in two (6.2%). CONCLUSIONS: The prevalence of factor V and factor II mutations is increased in patients with preeclampsia; the thrombophilic mutations may interact with other pathogenic factors to determine the clinical features of the disease and of its complications.     

Precise prenatal diagnosis of tuberous sclerosis by sequencing the TSC2 gene

BACKGROUND: The presumptive prenatal diagnosis of tuberous sclerosis (TSC) previously depended upon fetal imaging. Cloning of the two TSC genes (TSC1 and TSC2) now enables precise molecular diagnosis by gene sequencing. We used this approach for the prenatal diagnosis of a fetus showing multiple intracardiac tumors. METHODS: DNA extracted from cultivated amniotic fluid cells underwent sequencing of all coding regions and exon-intron boundaries of the TSC1 and TSC2 genes. RESULTS: A mutation (R611Q) was found in exon 16 of the TSC2 gene. Thus far, neither clinically unaffected parents has provided blood samples for mutation analysis. CONCLUSION: For the first time, mutation analysis of a TSC gene enabled a precise prenatal diagnosis. Copyright (c) 2005 John Wiley & Sons, Ltd.     

Polymorphisms of plasminogen activator inhibitor-1, angiotensin converting enzyme and coagulation factor XIII genes in patients with recurrent spontaneous abortion

We investigated polymorphisms of plasminogen activator inhibitor-1 (PAI-1), angiotensin converting enzyme (ACE ) and coagulation factor XIII (FXIII) genes and their association with recurrent spontaneous abortion (RSA) in Iranian patients and normal healthy controls. Ten (18.5%) patients were homozygote (4G/4G) for PAI-1 polymorphism, in contrast with two (2%) controls (p = 0.001). Patients with homozygote 4G mutation were significantly more prone to RSA in contrast to others (odds ratio: 11.0, 95% CI: 2.3–52.4). Nineteen (30.2%) patients and 25 (26.6%) controls were homozygote (DD) for ACE polymorphism. We observed only two patients and one control with homozygosity (34leu) for FXIII polymorphism. 4G/4G polymorphism for PAI-1 gene could be a thrombophilic mutation leading to abortion in Iranian population.     

Mutation analysis of BrCA1, BrCA2, and p53 versus soluble HLA class I and class II in a case of familial endometriosis

OBJECTIVE: To investigate possible correlation(s) between mutations of BrCA1, BrCA2, and p53 genes versus soluble HLA expression in familial endometriosis. DESIGN: Mutation analysis. SETTING: University teaching departments and hospital. PATIENT(S): A family with seven women in two generations with familial endometriosis. INTERVENTION(S): Mutation analysis of BrCA1, BrCA2, and p53 genes. MAIN OUTCOME MEASURE(S): A point mutation of the BrCA1 gene appears to inhibit soluble HLA secretion. RESULT(S): Among the three genes examined, only the BrCA1 gene showed a T to A mutation at position 3232 that correlates with total abolishment of both class I and class II antigen release. CONCLUSION(S): A possible correlation between a BrCA1 mutation and soluble HLA expression appears to exist. The mutation is not stage dependent and seemingly influences the secretion of both class I and class II antigens that are totally absent from the serum of only one family member.     

Estrogen receptor and laminin genetic polymorphism among women with pelvic organ prolapse

Objective

Laminin is a connective tissue component. The LAMC1 gene encodes for gamma-1 chain of laminin, which is associated with familial clustering of POP. The ERα gene which encodes for cellular estrogen receptor has also been associated with POP. The aim of this study was to evaluate a possible correlation between polymorphism in these genes and the risk for developing POP.

HPV prevalence, E6 sequence variation and physical state of HPV16 isolates from patients with cervical cancer in Sichuan, China

OBJECTIVES: Infection with high-risk human papillomavirus (hr-HPV) is an important factor associated with cervical cancer. The genetic mutation of HPV16 E6 and integration of HPV16 DNA in the cervical carcinoma tissues are considered important genetic changes in cervical lesion progression. But the studies of hr-HPV epidemiology are relatively less in the area of Sichuan, China. Therefore, we investigated the prevalence of 9 high-risk subtypes and analyzed the genetic mutation characteristic of HPV16 E6 and physical state of HPV16 DNA. METHODS: The fragments of L1 and E6 genes were amplified by PCR or nested PCR and then directly sequenced. Further, the multiplex PCR for HPV16 E2 and E6 genes was performed for detection of integration. RESULTS: HPV16, 58 and 18 were prominent, accounting for 78.6%, 20.0% and 9.7%, respectively in 145 isolates. E6 variants revealed that the European (EP) prototype and East Asia (EA) strain were 26 (23.0%) and 34 (30.1%), respectively. Furthermore, there were 14 base substitutions in E6 regions of the study group, of which 12 resulted in amino acid changes and the rest was silent mutation. Significantly, the 240G substitution exactly located the P53 degradation site. Overall, 8 of 114 (7.0%) isolates only contained integrated HPV16 DNA, 43 (37.7%) only contained episomal DNA and 63 (55.3%) contained both integrated and episomal DNA. The proportion of disruption of an intact E2 gene in the patients with cervical cancer is much lower than that in the previous studies. CONCLUSIONS: HPV16, 58 and 18 were mainly prevailing subtypes in patients with cervical cancer from Sichuan areas, China and EP/EA strains were predominant in these areas. Some mutations of E6 gene, which lead to the amino acid changes, may be more potentially carcinogenic and the proportion of disruption of an intact E2 gene is much lower.     

Feasibility of blood spot PCR in large-scale screening of fragile X syndrome in southern Taiwan.

BACKGROUND AND PURPOSE: Fragile X syndrome (FXS) is the most common form of hereditary mental retardation. Early diagnosis of the disease may lead to better prognosis for children who participate in early intervention programs. This study attempted to evaluate whether screening newborn boys with simple polymerase chain reaction (PCR) assay could be an effective approach for detection of mutation carriers and FXS, a process that may also facilitate detection of young carrier mothers. METHODS: Filter paper blood spot samples of 4843 newborn boys were collected from five hospitals in southern Taiwan. They were tested with a simple non-radioactive PCR for the presence of FMR1 gene mutation by determining the number of FMR1 CGG repeats. By this method, the examined sample can be reliably classified as normal (<40), intermediate (40-54), and mutant group (> 54), according to the number of CGG repeats. RESULTS: The FMR1 CGC repeat number of all but four samples was below 54, with 90 samples (1.8%) between 40 and 54 (the intermediate range). Two of the four abnormal samples were carriers of the premutation. The other two failed repeatedly in PCR amplification for the FMR1 gene, but not for the control K-ras gene. Hence, these samples seemed to be candidate carriers of large premutation or even full mutation, indicating the need for confirmation with standard Southern blot analysis. CONCLUSIONS: This study demonstrated that a simple PCR combined with blood spot sampling is effective and feasible for large-scale screening of newborn boys for fragile X carrier status. The relatively low carrier rate in this population suggests that the cost-effectiveness of implementation of such screening on a population-wide basis would be lower than in the Jewish and Caucasian populations.     

CYP1B1基因多态性与卵巢癌易感性的研究

目的:研究CYP1B1基因外显子2密码子119(G-T)、外显子3密码子432(C-G)多态性与卵巢癌遗传易感性的关系。方法:应用等位基因特异性聚合酶链反应(AS-PCR)法对53例卵巢癌患者和30例对照者进行CYP1B1基因密码子119(G-T)、密码子432(C-G)突变分析,用免疫组化SP法进一步研究雌激素受体(ER)、孕激素受体(PR)的表达,分析其是否受CYP1B1基因多态性的影响。结果:CYP1B1基因密码子432中等位基因C、G在卵巢癌组和对照组分布的差异有统计学意义(P<0.05),其中等位基因G使卵巢癌发病风险增加2.71倍。CYP1B1基因密码子432C/G各基因型分布两组间差异有统计学意义(P<0.01),纯合突变(G/G)基因型、杂合突变(C/G)基因型与野生(C/C)基因型相比,患卵巢癌的危险度分别提高了4.53倍和4.43倍。此外,432G/G、C/G基因型者ER阳性表达率高于432(C/C)基因型,三者间有显著差异(P<0.05)。结论:CYP1B1基因密码子432突变等位基因与卵巢癌的发生有一定关系,突变基因型增加了卵巢癌的发病风险,且与ER的表达相关。