Epigenetic profiling of the H19 differentially methylated region and comprehensive whole genome array-based analysis in Silver-Russell syndrome.

Silver-Russell syndrome (SRS) is a clinically and genetically heterogeneous congenital disorder characterized by severe growth retardation. Hypomethylation of the differentially methylated region (DMR) of the H19 gene and uniparental disomy of maternal chromosome 7 is present in ∼45% of the patients with SRS so more than half of these patients have no known genetic etiology. We combined several molecular technologies including multiplex methylation polymerase chain reaction, methylation-sensitive multiple ligation probe-dependent amplification, and methylation-sensitive high-resolution melting to assess the epigenetic status of 34 patients with SRS. Additionally, we applied a whole genome strategy to detect copy number changes and loss of heterozygosity. Thirteen patients (38.2%) had hypomethylation of the DMR of the H19 gene and none had uniparental disomy of maternal chromosome 7. The whole genome arrays identified five patients (14.7%) with microdeletions on chromosomes 1q23q24.3, 7p15.3, 13q31.3, 14q32.31, and 15q26.2qter, respectively. The overall mutation detection rate was 52.9% by the epigenetic study and the whole genome strategy. Although epimutation may be the major cause of SRS and can be identified by multiplex methylation polymerase chain reaction, the whole genome approach also provides information on the etiology of SRS. If no epimutation is identified in the patients with typical SRS, microdeletions should be suspected.

Mutation spectrum of the fibrillin-1 (FBN1) gene in Taiwanese patients with Marfan syndrome.

The aim of this study was to establish a national database of mutations in the fibrillin-1 (FBN1) gene that cause Marfan syndrome (MFS) in the Taiwanese population. In this study, we screened 294 patients from 157 families for the presence of FBN1 mutations using polymerase chain reaction/ denaturing high performance liquid chromatography (PCR/DHPLC). We identified 56 mutations in 62 of the 157 (40%) families including 49 single-base substitutions (36 missense mutations, seven nonsense mutations, and six splicing sites), one small insertion, four small deletions, one small indel (insertion and deletion), and one exonic deletion (Exon 36). When family history was taken into consideration, the mutation detection rate rose to 91% (29 of 32). We further investigated the phenotypic data and found that one third (47 of 157) of the families fit the Ghent criteria for MFS. Based on that data, the mutation rate was 98% (46/47). That finding implies that family history and the Ghent criteria play a more important role than clinical manifestations in establishing a clinical diagnosis of Marfan syndrome. Among the 56 mutations found in this study, 40 (71%) have not been registered in the Human Gene Mutation Database (HGMD) or in the Universal Mutation Database (UMD). This is the first study of the mutation spectrum of MFS in a cohort of patients in Taiwan. The database is expected to considerably improve genetic counseling for and medical care of MFS families.

Side effects after docetaxel treatment in Taiwanese breast cancer patients with CYP3A4, CYP3A5, and ABCB1 gene polymorphisms.

BACKGROUND: Breast cancer patients initiating TEC (including docetaxel, epirubicin, and cyclophosphamide) treatment were genotyped for CYP3A4, CYP3A5, and ABCB1 to identify variability factors of side effects for docetaxel. METHODS: The planned dose of docetaxel per course was formulated according to each patient's height and weight. Each participant had received TEC treatment for 6 consecutive cycles. The single nucleotide polymorphisms (SNPs) of CYP3A4*4 (352A > G), CYP3A4*5 (653C > G), and CYP3A4*18A (20070T > C) for the CYP3A4 gene, CYP3A5*3A (6986A > G) for the CYP3A5 gene, and -41A > G, -145C > G, 1236C > T, 2677G > T(A), and 3435C > T SNPs for the ABCB1 gene were determined by using the restriction fragment length polymorphism of polymerase chain reaction products and the restriction enzymes. RESULTS: Fifty-nine Taiwanese women (mean age, 46 y; range, 30-64 y) treated for breast cancer with TEC were recruited. We found that patients carrying the CYP3A5*1/*3 genotype demonstrated more side effects of fever, pleural effusion, and febrile neutropenia than those with the CYP3A5*3/*3 genotype (p = 0.075, 0.077, and 0.030, respectively); moreover, patients with the ABCB1 2677G/G genotype also showed more side effects of fever and febrile neutropenia than those with other genotypes (p = 0.024 and 0.027), In regard to ABCB1 3435C>T, patients with ABCB1 3435C/C tended to suffer leucopenia (p = 0.057). CONCLUSIONS: There could be correlations between certain side effects of docetaxel treatment and polymorphisms of these metabolic enzymes. Unfortunately, there is not so much evidence due to the small sample size of this study which restricts the statistical power.

Identification of fibrillin-1 gene mutations in Marfan syndrome by high-resolution melting analysis.

Marfan syndrome has been associated with approximately 562 mutations in the fibrillin-1 (FBN1) gene. Mutation scanning of the FBN1 gene with DNA direct sequencing is time-consuming and expensive because of its large size. This study analyzed the diagnostic value of high-resolution melting analysis as an alternative method for scanning of the FBN1 gene. A total of 75 polymerase chain reaction (PCR) amplicons (179-301bp, average 256bp) that covered the complete coding regions and splicing sites were evaluated on the 96-well LightCycler system. Melting curves were analyzed as fluorescence derivative plots (-dF/dT vs. temperature). To determine the sensitivity of this method, a total of 82 samples from patients with Marfan syndrome and 50 unaffected individuals were analyzed. All mutations reported in this study had been confirmed previously by direct sequencing analysis. Melting analysis identified 48 heterozygous variants. The variant c.3093 G>T (exon 25) was incorrectly identified by melting curve analysis. The sensitivity of the technique in this sample was 98.78% (81/82). This study demonstrated that high-resolution melting analysis is a reliable gene scanning method with greater speed than DNA sequencing. Our results support the use of this technology as an alternative method for the diagnosis of Marfan syndrome as well as its suitability for high-throughput mutation scanning of other large genes.