Performance evaluation of the TheraTyper-GJB2 assay for detection of GJB2 gene mutations.

Mutations in the GJB2 gene are the most common cause of congenital hearing loss in many populations. This study describes the development of a matrix-assisted laser desorption/ionization time-of-flight mass spectrometry-based minisequencing assay, TheraTyper-GJB2, for the detection of c.35delG, c.167delT, and c.235delC mutations in the GJB2 gene. This assay was evaluated for analytic performance, including detection limit, interference, cross-reactivity, and precision, using GJB2 reference standards prepared by site-directed mutagenesis of a molecular clone. The detection limit was as low as 0.040 ng of human genomic DNA per PCR. No cross-reactivity with bacteria and viruses and no negative effects of increased levels of various potential interfering substances was observed. A precision test involving repetitive analysis of 2400 replicates showed 99.9% agreement (2397 of 2,400) with 99.8% (95% CI, 99.7%-99.8%) sensitivity and 100.0% (95% CI, 99.3%-100.0%) specificity. TheraTyper-GJB2 and direct sequencing assays showed 100% concordance for detecting mutations in 1,113 clinical specimens. Overall, TheraTyper-GJB2 showed comparable performance for detecting GJB2 mutations in reference and clinical samples with that of direct sequencing, and easier interpretation of results for analysis of a large quantity of samples. Therefore, the TheraTyper-GJB2 assay will be practically useful for the diagnosis of GJB2 mutations associated with congenital hearing loss with faster, cheaper, more reliable, and high-throughput capability.

Performance evaluation of the HepB Typer-Entecavir kit for detection of entecavir resistance mutations in chronic hepatitis B.

BACKGROUND/AIMS: Molecular diagnostic methods have enabled the rapid diagnosis of drug-resistant mutations in hepatitis B virus (HBV) and have reduced both unnecessary therapeutic interventions and medical costs. In this study we evaluated the analytical and clinical performances of the HepB Typer-Entecavir kit (GeneMatrix, Korea) in detecting entecavir-resistance-associated mutations. METHODS: The HepB Typer-Entecavir kit was evaluated for its limit of detection, interference, cross-reactivity, and precision using HBV reference standards made by diluting high-titer viral stocks in HBV-negative human serum. The performance of the HepB Typer-Entecavir kit for detecting mutations related to entecavir resistance was compared with direct sequencing for 396 clinical samples from 108 patients. RESULTS: Using the reference standards, the detection limit of the HepB Typer-Entecavir kit was found to be as low as 500 copies/mL. No cross-reactivity was observed, and elevated levels of various interfering substances did not adversely affect its analytical performance. The precision test conducted by repetitive analysis of 2,400 replicates with reference standards at various concentrations showed 99.9% agreement (2398/2400). The overall concordance rate between the HepB Typer-Entecavir kit and direct sequencing assays in 396 clinical samples was 99.5%. CONCLUSIONS: The HepB Typer-Entecavir kit showed high reliability and precision, and comparable sensitivity and specificity for detecting mutant virus populations in reference and clinical samples in comparison with direct sequencing. Therefore, this assay would be clinically useful in the diagnosis of entecavir-resistance-associated mutations in chronic hepatitis B.

Mutational complex genotype of the hepatitis B virus X /precore regions as a novel predictive marker for hepatocellular carcinoma.

This study explored the combined effect of number and pattern of mutations in the X/precore regions of the hepatitis B virus (HBV) genome, mutational complex genotype (MCG), on hepatocellular carcinoma (HCC) development. Sequence variations were determined by direct sequencing and multiplex restriction fragment mass polymorphism analysis in 150 age-, sex- and hepatitis B e antigen (HBeAg) status-matched patients with and without HCC. In addition, a longitudinal study and an external validation of MCG were conducted. All were HBV subgenotype C2. Eight high-frequency mutations (G1613A, C1653T, T1753V, A1762T, G1764A, A1846T, G1896A and G1899A) were significantly associated with HCC. Whereas C1653T, T1753V, G1764A and A1846T were independent mutational factors for HCC, the significance of these individual mutations was negligible when analyzed with all clinico-virological variables. The total number of mutations was the only independent viral factor for HCC, irrespective of HBeAg status. There was a significant dose-risk relationship between the number of mutations and HCC, in which high risks for HCC were associated with mutation numbers ≥ 6. Pattern analysis of the mutations revealed disparity in distribution among the top seven high-risk mutation combination patterns, which accounted for 40 and 2.7% of HCC and non-HCC cases, respectively. The predictive accuracy of the high-risk mutations for HCC was similar to that of α-fetoprotein. Longitudinal and external validation studies also supported the association of mutation number with HCC development. MCG in the HBV X/precore regions is a risk indicator for HCC, and might serve as a new guide to the HCC screening scheme for chronic HBV carriers.

Possible association of SLC22A2 polymorphisms with aspirin-intolerant asthma.

BACKGROUND: Aspirin-intolerant asthma (AIA) is a clinical syndrome characterized by acute bronchoconstriction following the ingestion of aspirin. Solute carrier family 22, member 2 (SLC22A2), also known as organic cation transporter 2 (OCT2), is predominantly expressed in the luminal membrane of airway epithelial cells and has been shown to mediate the transport of prostaglandins on the cyclooxygenase pathway which is regulated by aspirin blockage. Recently, SLC22A2-mediated uptake inhibition by several nonsteroidal anti-inflammatory drugs and decreased SLC22A2 transport activity by its genetic variants have been elucidated in asthma. METHODS: To investigate the associations between AIA and genetic polymorphisms of the SLC22A2 gene, 18 variants were genotyped in 163 AIA subjects and 429 aspirin-tolerant asthma (ATA) controls. Logistic analyses were used to evaluate p values for the associations of SLC22A2 polymorphisms with AIA. RESULTS: One common polymorphism in intron 5, i.e. rs316021, was significantly associated with susceptibility to AIA (p = 0.004, P(corr) = 0.05, OR = 0.60, 95% CI = 0.43-0.85 in a codominant model). The minor allele frequency of rs316021 in the AIA group was significantly lower than that in the ATA controls. In addition, a polymorphism in intron 4 (rs3912161) and a haplotype (SLC22A2-ht3) showed significantly stronger association signals with the FEV(1) fall rate induced by aspirin provocation in AIA subjects compared with ATA controls (p = 0.004, P(corr) = 0.05). CONCLUSION: Our findings suggest that SLC22A2 could be a susceptibility gene for aspirin intolerance in asthmatics.

Association of SLC6A12 variants with aspirin-intolerant asthma in a Korean population.

Aspirin-intolerant asthma (AIA) occurs from asthma exacerbation after exposure to aspirin. However, the underlying mechanisms of AIA occurrence are still unclear. The critical role of the solute carrier family 6 (neurotransmitter transporter, betaine/GABA) member 12 (SLC6A12) gene in GABAergic transmission, which is associated with mucus production in asthma, makes it a candidate gene for AIA association study. Eight single nucleotide polymorphisms (SNPs) in SLC6A12 were genotyped in 163 aspirin-intolerant asthma (AIA) and 429 aspirin-tolerant asthma (ATA) patients of Korean ethnicity. Associations between polymorphisms of SLC6A12 and AIA were analysed using multivariate logistic analysis. Results showed that two polymorphisms and a haplotype in SLC6A12, rs499368 (P= 0.005; P(corr)= 0.03), rs557881 (non-synonymous C10R, P= 0.007; P(corr)= 0.04), and SLC6A12_BL1_ht1 (P= 0.009; P(corr)= 0.05) respectively, were significantly associated with AIA after multiple testing corrections. In addition, SNPs of SLC6A12 were significantly associated with the fall rate of FEV(1) by aspirin provocation suggesting that SLC6A12 could affect reversibility of lung function abnormalities in AIA patients. Although these results are preliminary and future replications are needed to confirm these findings, this study showed evidence of association between variants in SLC6A12 and AIA occurrence among asthmatics in a Korean population.

Association of ZDHHC8 polymorphisms with smooth pursuit eye movement abnormality.

The zinc finger DHHC domain-containing protein 8 (ZDHHC8) is located in the 22q11 microdeletion region and may contribute to the behavioral deficit associated with 22q11 deletion syndrome. Although polymorphisms of ZDHHC8 have been reported to be associated with the risk of schizophrenia, those associations are still controversial. This study was performed to validate the genetic association of ZDHHC8 polymorphisms with the risk of schizophrenia, and also to scrutinize the association with smooth pursuit eye movement (SPEM) abnormality in a Korean population. Five SNPs of ZDHHC8 were genotyped by TaqMan assay. Their genetic effects on the risk of schizophrenia were analyzed in 354 patients and 396 controls using allele-based chi(2) analyses. Association of ZDHHC8 polymorphisms with SPEM abnormality among 166 schizophrenic patients were analyzed using multiple regressions. No ZDHHC8 polymorphisms were found to be associated with the risk of schizophrenia. However, four SNPs and one haplotype (ht4) were strongly associated with the risk of SPEM abnormality even after multiple correction (P = 0.00005-0.0007, P(corr) = 0.0001-0.002). The results of the present study provide the first evidence that ZDHHC8 on the 22q11 locus might have influence on SPEM function of schizophrenia patients in a Korean population and may provide a new clue for understanding differential effects of candidate genes in schizophrenia.

Identification of copy number variations and common deletion polymorphisms in cattle.

BACKGROUND: Recently, the discovery of copy number variation (CNV) led researchers to think that there are more variations of genomic DNA than initially believed. Moreover, a certain CNV region has been found to be associated with the onset of diseases. Therefore, CNV is now known as an important genomic variation in biological mechanisms. However, most CNV studies have only involved the human genome. The study of CNV involving other animals, including cattle, is severely lacking. RESULTS: In our study of cattle, we used Illumina BovineSNP50 BeadChip (54,001 markers) to obtain each marker's signal intensity (Log R ratio) and allelic intensity (B allele frequency), which led to our discovery of 855 bovine CNVs from 265 cows. For these animals, the average number of CNVs was 3.2, average size was 149.8 kb, and median size was 171.5 kb. Taking into consideration some overlapping regions among the identified bovine CNVs, 368 unique CNV regions were detected. Among them, there were 76 common CNVRs with > 1% CNV frequency. Together, these CNVRs contained 538 genes. Heritability errors of 156 bovine pedigrees and comparative pairwise analyses were analyzed to detect 448 common deletion polymorphisms. Identified variations in this study were successfully validated using visual examination of the genoplot image, Mendelian inconsistency, another CNV identification program, and quantitative PCR. CONCLUSIONS: In this study, we describe a map of bovine CNVs and provide important resources for future bovine genome research. This result will contribute to animal breeding and protection from diseases with the aid of genomic information.

CCND2 polymorphisms associated with clearance of HBV infection.

Cyclin D2s (CCND2s) are members of the D-type cyclin family. They interact and construct complexes with cyclin-dependent kinase (CDK)4 or 6. The cyclin D2/CDK4 or CDK6 complexes have key roles in controlling the progression of cell cycle from the Gap 1 (G1) phase to the synthesis (S) phase. Overexpression of cyclin D2 is associated with the development of tumors. In this study, we identified 16 sequence variants of CCND2 polymorphisms through direct DNA sequencing in 24 individuals, and 5 common variants were selected for genotyping in larger-scale subjects (n=1100). Genetic associations of those polymorphisms with hepatitis B virus (HBV) clearance and hepatocellular carcinoma (HCC) outcome among patients with HBV were analyzed. Although no significant association was observed between the polymorphisms and HCC outcome among HBV patients, one common polymorphism in the 5'-untranslated region (that is, rs1049606) and the most common haplotype (CCND-ht1 [T-C-T-A-T]), however, were significantly associated with HBV clearance (odds ratio=0.69, P=0.0002, Pcorr=0.001 and odds ratio=1.37, P=0.0009, Pcorr=0.004, respectively). The minor allele frequency of rs1049606 among the spontaneously recovered (SR) group was significantly higher than that of the chronic carrier (CC) group (frequency=0.403 vs 0.336, P=0.0002). In contrast, the frequency of CCND-ht1 was higher among the CC group than among the SR group (frequency=0.429 vs 0.374, P=0.0009). The information identified in this study might provide valuable insights into generating strategies for control of HBV.

Identification of genome-wide copy number variations and a family-based association study of Avellino corneal dystrophy.

OBJECTIVE: To determine the association of identified copy number variations (CNVs) in whole genome with the risk of Avellino corneal dystrophy (ACD) in a Korean population. DESIGN: Case-control study. PARTICIPANTS: A total of 146 patients with ACD and 226 control subjects. METHODS: A total of 193 trios were genotyped by the Illumina HumanHapCNV370-Duo BeadChip (370,404 markers) (Illumina, Inc., San Diego, CA). The intensity signal (log R ratio) and allelic intensity ratio (B allele frequency) of each marker in all individuals were obtained by Illumina BeadStudio software (Illumina, Inc.). To obtain authentic CNVs in this study, we performed a family-based CNV validation and family-based boundary mapping using the PennCNV algorithm, which incorporates multiple factors, including total log R ratio, B allele frequency, and family information, based on an integrated hidden Markov model. MAIN OUTCOME MEASURES: Statistical comparison and identification of CNVs between case and control using family information. RESULTS: We identified 27,267 individual trio CNVs with a median size of 16.2 kb, aggregated in 2245 CNV regions. Most of the identified trio CNVs in this study showed well-defined CNV boundaries and overlapped with those in the Database of Genomic Variants (DGV) (83.4% in number and 79.2% in length). With the common CNV regions (264 CNV regions >5%), we performed a family-based association test with the risk of ACD. CONCLUSIONS: Two CNV regions (chr6:29978470-29987783 and chr14:59896944-59916129) were significantly associated with the risk of ACD (P=0.05-0.003 and P=0.008, respectively). This study describes the first results of a genome-wide association analysis of individual CNVs with the risk of ACD and shows that 2 novel CNV loci may be involved in the risk of ACD. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Common CYP7A1 promoter polymorphism associated with risk of neuromyelitis optica.

Neuromyelitis optica (NMO) is a severe idiopathic inflammatory disease of the central nervous system primarily affecting the optic nerves and spinal cord. In this study, we generated genome-wide SNP data from NMO patients and normal controls (53 cases and 240 controls), and followed up on the association signals with samples from a larger number of inflammatory demyelinating diseases, including NMO (n=93), multiple sclerosis (MS, n=71), idiopathic recurrent transverse myelitis (IRTM, n=57), and normal controls (n=240). Statistical analyses revealed that a common promoter SNP in CYP7A1 has a protective/gene dose-dependent effect on the risk of NMO (P=0.0004). A stronger association between the variables and subsequently, a higher protective effect (lower OR) on the risk of NMO were observed among patients carrying the "G/G" genotype of rs3808607 than those with the "T/G" genotype (OR=0.38/P=0.01 vs. OR=0.12/P=0.0004, respectively). The associations which were only observed in patients with NMO suggest that there are differences in the genetic etiology of the inflammatory demyelinating diseases (NMO, classical MS, and IRTM).

MYLK polymorphism associated with blood eosinophil level among asthmatic patients in a Korean population.

The myosin light chain kinase (MYLK) gene encodes both smooth muscle and nonmuscle cell isoforms. Recently, polymorphisms in MYLK have been reported to be associated with several diseases. To examine the genetic effects of polymorphisms on the risk of asthma and related phenotypes, we scrutinized MYLK by re-sequencing/genotyping and statistical analysis in Korean population (n = 1,015). Seventeen common polymorphisms located in or near exons, having pairwise r ( 2 ) values less than 0.25, were genotyped. Our statistical analysis did not replicate the associations with the risk of asthma and log-transformed total IgE levels observed among African descendant populations. However, two SNPs in intron 16 (+89872C > G and +92263T >C), which were in tight LD (|D'| = 0.99), revealed significant association with log-transformed blood eosinophil level even after correction multiple testing (P = 0.002/P( corr )= 0.01 and P = 0.002/P( corr ) = 0.01, respectively). The log-transformed blood eosinophil levels were higher in individuals bearing the minor alleles for +89872C > G and +92263T > C, than in those bearing other allele. In additional subgroup analysis, the genetic effects of both SNPs were much more apparent among asthmatic patients and atopic asthma patients. Among atopic asthma patients, the log-transformed blood eosinophil levels were proportionally increased by gene-dose dependent manner of in both +89872C > G and +92263T > C (P = 0.0002 and P = 0.00007, respectively). These findings suggest that MYLK polymorphisms might be among the genetic factors underlying differential increases of blood eosinophil levels among asthmatic patients. Further biological and/or functional studies are needed to confirm our results.

Putative association of DNA methyltransferase 1 (DNMT1) polymorphisms with clearance of HBV infection.

DNA methyltransferase (DNMT) 1 is the key enzyme responsible for DNA methylation, which often occurs in CpG islands located near the regulatory regions of genes and affects transcription of specific genes. In this study, we examined the possible association of DNMT1 polymorphisms with HBV clearance and the risk of hepatocellular carcinoma (HCC). Seven common polymorphic sites were selected by considering their allele frequencies, haplotype-tagging status and LDs for genotyping in larger-scale subjects (n = 1,100). Statistical analysis demonstrated that two intron polymorphisms of DNMT1, +34542G > C and +38565G > T, showed significant association with HBV clearance in a co-dominant model (OR = 1.30, P(corr) = 0.03) and co- dominant/recessive model (OR = 1.34-1.74, P(corr) = 0.01-0.03), respectively. These results suggest that two intron polymorphisms of DNMT1,+34542G > C and +38565G > T, might affect HBV clearance.

Antegrade humeral nailing through the rotator cuff interval: a new entry portal.

The conventional approach for antegrade intramedullary nailing (AIN) of humerus fractures is associated with persistent pain and compromised shoulder function. Damage to the critical hypovascular zone of the rotator cuff near its insertion on the humerus and/or irritation of the subacromial space by prominent hardware are the factors believed to be responsible for poor shoulder function after AIN of the humerus. This study describes a new entry portal through the rotator interval that minimizes iatrogenic damage to the rotator cuff at its insertion. This approach offers a solution for the disappointing postoperative shoulder function and pain scores associated with conventional antegrade nailing techniques. This study consisted of 33 patients with 34 humeral fractures followed for an average of 34 months. The overall satisfaction rate was more than 90%, according to the ASES (American Shoulder and Elbow Society) score. The mean Constant Score was 84 (SD, 14; range, 17 to 98), and primary bone union was achieved in 32 of the 34 cases.