Response to interferon-beta treatment in multiple sclerosis patients: a genome-wide association study

Up to 50% of multiple sclerosis (MS) patients do not respond to interferon-beta (IFN-β) treatment and determination of response requires lengthy clinical follow-up of up to 2 years. Response predictive genetic markers would significantly improve disease management. We aimed to identify IFN-β treatment response genetic marker(s) by performing a two-stage genome-wide association study (GWAS). The GWAS was carried out using data from 151 Australian MS patients from the ANZgene/WTCCC2 MS susceptibility GWAS (responder (R)=51, intermediate responders=24 and non-responders (NR)=76). Of the single-nucleotide polymorphisms (SNP) that were validated in an independent group of 479 IFN-β-treated MS patients from Australia, Spain and Italy (R=273 and NR=206), eight showed evidence of association with treatment response. Among the replicated associations, the strongest was observed for FHIT (Fragile Histidine Triad; combined P-value 6.74 × 10^-6) and followed by variants in GAPVD1 (GTPase activating protein and VPS9 domains 1; combined P-value 5.83 × 10^-5) and near ZNF697 (combined P-value 8.15 × 10^-5).

Influence of elevated liver fat on circulating adipocytokines and insulin resistance in obese Hispanic adolescents

OBJECTIVE

We performed this study to examine the metabolic differences arising from higher liver fat accumulation in obese Hispanic adolescents, with a particular focus on circulating levels of adipocytokines and insulin resistance.

METHODS

Forty-one obese Hispanic adolescents (15.3 ± 1.0 years, body mass index percentile: 97.0 ± 3.9) were assessed for: visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) and hepatic fat fraction (HFF) by magnetic resonance imaging; fasting measures of serum glucose, insulin and adipocytokines; homeostasis model assessment of insulin resistance (HOMA-IR); and insulin sensitivity (SI) and the acute insulin response to glucose (AIR) by intravenous glucose tolerance test. Subjects with normal levels of HFF (below 5%; n = 25) were compared to those with HFF > 5% (n = 16).

RESULTS

The two groups differing in HFF were similar for total body fat, VAT and SAT. The group with HFF > 5% had significantly (P < 0.05) higher interleukin-8 (IL-8) (6.1 ± 1.6 vs. 3.2 ± 0.4 pg mL(-1) ), NGF (30.2 ± 9.9 vs. 13.9 ± 1.6 pg mL(-1) ), HOMA-IR (8.8 ± 1.1 vs. 5.5 ± 0.5), AIR (1869 ± 206 vs. 1092 ± 165) and a tendency for lower SI (1.2 ± 0.4 vs. 2.1 ± 0.3; P = 0.06), with no significant differences in any of other factors measured.

CONCLUSIONS

These data suggest that elevated liver fat is most closely associated with elevated serum IL-8 and NGF levels as well as increased AIR and HOMA-IR. These elevated factors may play significant roles in the metabolic abnormalities associated with elevated liver fat in obese Hispanics.

Dietary alterations due to perceptions in acute viral hepatitis lead to sub-optimal calorie intake and increased length of hospitalization

Although there are no dietary restrictions recommended in acute viral hepatitis (AVH), there is an altered food intake, probably because of perceptions and traditional nutritional practices, leading to sub-optimal intake and poorer clinical outcome. Therefore, we aimed to determine nutritional intake of AVH patients before and after disease onset and to investigate if optimal intake following nutrition education shortened the length of hospitalization (LOH). Seventy-five patients with AVH were interviewed for foods consumed and avoided because of perceptions during illness. Nutrition education was given to all patients with meal plan. In-patients were monitored for their nutritional intake until discharge. All patients were followed up after 2 weeks to assess compliance to the plan. There was a statistically significant decrease in mean calorie and protein intake in AVH patients during illness [1314 kcal (standard deviation, SD 291) and 27.5 g (SD 8.84)] when compared with that before onset of the disease [1873 kcal (SD 246) and 51.5 g (SD 8.03); P < 0.0001]. Mean LOH in patients consuming a high calorie diet [6.28 days (SD 2.91)] was significantly lower than those consuming low calories [8.36 days (SD 2.59), P = 0.024]. Two-week follow up revealed that 70% of patients modified their diet to a balanced normal diet as per the given plan. Our study showed that AVH patients consumed sub-optimal calories because of perceptions and traditional nutritional practices. Nutrition education played a major role in achieving overall nutritional goals and in decreasing the LOH.

High-sensitivity KRAS mutation detection in colorectal and lung cancer using SURVEYOR Nuclease scanning

e22023

Background: Mutations of the KRAS gene in colorectal and lung cancers have been associated with lack of response to epidermal growth factor receptor (EGFR) inhibitor therapies. Here we describe a highly sensitive assay that identifies mutations by scanning the entire coding region of KRAS exons 2 and 3 using SURVEYOR Nuclease, an endonuclease that cleaves double-stranded heteroduplex DNA at base pair mismatch sites. Methods: DNA was extracted from formalin-fixed paraffin- embedded tissue sections from a set of 30 colorectal and lung cancer samples. Two amplicons covering the coding and splice junction regions of the KRAS gene exons 2 and 3 were PCR-amplified, hybridized to allow heteroduplex formation, incubated with SURVEYOR Nuclease and analyzed on the WAVE-HS DHPLC system. The sensitivity of SURVEYOR Nuclease mutation detection was assessed by creating serial dilutions of 50:50 mixtures of original PCR products from mutant samples with wild type amplicons from control DNA. Results: 6 samples were identified as KRAS mutant by WAVE-HS profiles containing two fragment peaks in addition to the full length amplicon peak, indicating SURVEYOR Nuclease cleavage at a mismatch site. Mutations were found in both exon 2 (codons 12, 13) and exon 3 (codon 59). Sequencing confirmed the KRAS mutations in these samples. Levels of mutant DNA as low as 2% (1 ng/ul) were identified by this method, consistent with other SURVEYOR-based assays. Conclusions: SURVEYOR Nuclease technology is a sensitive and comprehensive method for detecting mutation in KRAS.

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Association of cathepsin B gene polymorphisms with tropical calcific pancreatitis

BACKGROUND AND AIMS

Tropical calcific pancreatitis (TCP) is a type of chronic pancreatitis unique to countries in the tropics. Mutations in pancreatic secretory trypsin inhibitor (SPINK1) rather than cationic trypsinogen (PRSS1) explain the disease in only 50% of TCP patients. As cathepsin B (CTSB) is known to activate cationic trypsinogen, we attempted to understand the role of CTSB mutations in TCP. Evidence of epistatic interaction was investigated with the previously associated N34S SPINK1 allele, a variant considered to be a modifier rather than a true susceptibility allele.

SUBJECTS AND METHODS

We sequenced the coding region of CTSB gene in 51 TCP patients and 25 controls and further genotyped 89 patients and 130 controls from the same cohort for Leu26Val, C595T, T663C, and Ser53Gly polymorphisms. The positive findings observed in the earlier cohort were re-examined in an ethnically matched replication cohort comprising 166 patients and 175 controls. Appropriate statistical analyses were performed and Bonferroni correction for multiple testing was applied.

RESULTS

We found a statistically significant association of the Val26 allele at Leu26Val polymorphism with an odds ratio (OR) of 2.15 (95% confidence interval (CI) 1.60-2.90 (p = 0.009)), after Bonferroni correction (corrected p value = 0.025). This significant association of Leu26Val with TCP was replicated in another cohort (OR 2.10 (95% CI 1.56-2.84); p = 0.013). Val26 allele also showed significantly higher frequency in N34S positive and N34S negative patients than in controls (p = 0.019 and 0.013, respectively). We also found significant differences in the mutant allele frequencies at Ser53Gly and C595T single nucleotide polymorphisms between N34S positive patients and controls (p = 0.008 and 0.001, respectively). Although haplotype analysis did not complement the results of allelic association, it did uncover a unique haplotype protective for TCP (p = 0.0035).

CONCLUSION

Our study suggests for the first time that CTSB polymorphisms are associated with TCP. As PRSS1 mutations are absent in TCP and the N34S SPINK1 mutation is proposed to play a modifier role, these variants may be critical as a trigger for cationic trypsinogen activation.