Novel biomarkers for inborn errors of metabolism in the metabolomics era

Inborn errors of metabolism arise due to deficiency of enzymes in metabolic pathways. Recent years have seen the onset of novel technologies like proteomics, metabolomics, lipidomics, and urinomics. In the past many novel biomarkers have been developed like succinyl acetone for tyrosinemia, a number of organic acids for organic acidurias, acylcarnitines for the detection of fatty acid oxidation disorders and organic acidurias etc. With the advent of the -omics technologies, the number of novel biomarkers has increased dramatically. The use of techniques like mass spectrometry and NMR spectroscopy has led to a faster diagnosis of inborn errors of metabolism and smaller sample requirement. Hundreds of markers can be detected in a single urine sample, making diagnosis easier. There is an urgent need for implementing such techniques into routine practice in India.

Alterations in the levels of plasma amino acids in polycystic ovary syndrome- A pilot study.

Background & objectives: Plasma amino acid levels are known to be altered in conditions like sepsis and burns which are situations of metabolic stress. Polycystic ovary syndrome (PCOS), a condition which affects a woman throughout her life, is said to be associated with metabolic stress. This study was undertaken to assess if there were significant alterations in the levels of plasma amino acids in women with PCOS. Methods: Sixty five women with PCOS along with the similar number of age matched normal controls were included in this study. Levels of 14 amino acids were determined using reverse phase high performance liquid chromatography. Results: The levels of methionine, cystine, isoleucine, phenylalanine, valine, tyrosine, proline, glycine, lysine and histidine were found to be significantly (P<0.001) lower in cases than in controls. Arginine and alanine levels were found to be significantly (P<0.001) higher in cases compared with controls. Interpretation & conclusions: Our findings showed significant derangement in the levels of plasma amino acids in women with PCOS which might be due to the oxidative and metabolic stress associated with it. Further studies need to be done to confirm the findings.

Assessment of cassava toxicity in patients with tropical chronic pancreatitis.

Background and aim: There have been conflicting reports on the role of cassava ingestion in tropical pancreatitis (TCP). In this study we aimed to estimate cyanogens detoxifying enzyme rhodanese, thiocyanate and sulfur containing amino acids in cassava consumer as well as cassava non-consumer TCP patients and healthy controls and compare the same. Methods: Eighty-six TCP patients and 90 healthy controls were recruited. Serum rhodanese, thiocyanate, plasma amino acids, urinary inorganic sulfate/creatinine were measured. Results: There was significant reduction in serum rhodanese activity in both cassava consumer- and non-consumer TCP patients as compared to controls but no significant difference between cassava consumer- and non-consumer TCP patients was observed. Serum thiocyanate was significantly lower in cassava consumer TCP patients as compared to cassava consumer controls but not significantly different from cassava non-consumer TCP patients. Plasma methionine, cysteine and urinary inorganic sulfate / creatinine ratio was significantly lower in both cassava consumer and non-consumer TCP patients as compared to controls but were comparable among cassava consumers and non-consumers. Conclusions: Significant reduction in rhodanese activity with concomitant decrease in sulfur containing amino acids and antioxidants such as glutathione suggests that TCP patients are at higher risk of defective detoxification of cyanogens. However there was no difference between cassava consumers and non-consumers. Low levels of sulfur amino acids may contribute to the development of pancreatitis.

Assessment of oxidative status in chronic pancreatitis and its relation with zinc status.

Background Oxidative stress-induced free radicals have been implicated in the pathology of chronic pancreatitis (CP). Aim We aimed to estimate oxidative stress and antioxidant status in tropical chronic pancreatitis (TCP) and alcoholic chronic pancreatitis (ACP) and correlate with zinc status. Methods One hundred and seventy-five CP patients (91 TCP, 84 ACP) and 113 healthy subjects were prospectively studied. Disease characteristics and imaging features were recorded. Erythrocyte reduced glutathione, glutathione peroxidase (GPx), superoxide dismutase (SOD), plasma vitamin C, and erythrocyte thiobarbituric acid reactive substance (TBARS) were estimated by spectrophotometry. Erythrocyte zinc was estimated by flame atomic absorption spectrophotometry. Results Enhanced lipid peroxidation with concomitant decrease in antioxidant status was observed in both TCP and ACP patients (p<0.05). The findings were comparable in both diabetic and non-diabetic CP patients. Significantly, lower plasma vitamin C and elevated levels of erythrocyte TBARS was noted in TCP as compared to ACP patients. The erythrocyte zinc significantly correlated with SOD activity (r=0.450, p<0.001). Conclusions Our study corroborates the role of oxidative stress in CP and suggests some differences in oxidative status in TCP and ACP patients. Zinc deficiency appears to affect oxidative status in CP patients.

Fecal elastase1 and acid steatocrit estimation in chronic pancreatitis.

Background Measurement of pancreatic exocrine function and steatorrhea in chronic pancreatitis in the clinical setting has not received much attention. Aim To assess pancreatic exocrine function and fecal fat excretion in a cohort of patients with chronic pancreatitis. Methods Stool elastase1 levels were measured in 101 patients using polyclonal ELISA and acid steatocrit was measured in 86 chronic pancreatitis patients. Associations with etiology, clinical and radiological features, and diabetic status were examined. Results Low pancreatic stool elastase1 (<200 μg/g stool) was observed in two-thirds of chronic pancreatitis patients and correlated with ductal dilatation, pancreatic atrophy and calcification (p<0.05). Diabetes was more prevalent in chronic pancreatitis patients with low elastase1 (p=0.045). There was no difference in mean acid steatocrit between diabetics and non-diabetics (p=0.069). Elastase1 levels had a negative correlation with acid steatocrit (r=–0.606, p<0.001), and a positive correlation (r=0.412) with body mass index (p=0.013). Fiftythree percent of chronic pancreatitis patients with normal BMI had low elastase1. Conclusions Fecal elastase1 levels correlated with fecal fat excretion and BMI. Fecal elastase1 estimation may be helpful in early detection of malabsorption in chronic pancreatitis.

BRCA1 and BRCA2 germline mutation analysis among Indian women from south India: identifi cation of four novel mutations and high-frequency occurrence of 185delAG mutation.

Mutations in the BRCA1 and BRCA2 genes profoundly increase the risk of developing breast and/or ovarian cancer among women. To explore the contribution of BRCA1 and BRCA2 mutations in the development of hereditary breast cancer among Indian women, we carried out mutation analysis of the BRCA1 and BRCA2 genes in 61 breast or ovarian cancer patients from south India with a positive family history of breast and/or ovarian cancer. Mutation analysis was carried out using conformation-sensitive gel electrophoresis (CSGE) followed by sequencing. Mutations were identifi ed in 17 patients (28.0%); 15 (24.6%) had BRCA1 mutations and two (3.28%) had BRCA2 mutations. While no specifi c association between BRCA1 or BRCA2 mutations with cancer type was seen, mutations were more often seen in families with ovarian cancer. While 40% (4/10) and 30.8% (4/12) of families with ovarian or breast and ovarian cancer had mutations, only 23.1% (9/39) of families with breast cancer carried mutations in the BRCA1 and BRCA2 genes. In addition, while BRCA1 mutations were found in all age groups, BRCA2 mutations were found only in the age group of ≤40 years. Of the BRCA1 mutations, there were three novel mutations (295delCA; 4213T→A; 5267T→ G) and three mutations that have been reported earlier. Interestingly, 185delAG, a BRCA1 mutation which occurs at a very high frequency in Ashkenazi Jews, was found at a frequency of 16.4% (10/61). There was one novel mutation (4866insT) and one reported mutation in BRCA2. Thus, our study emphasizes the importance of mutation screening in familial breast and/or ovarian cancers, and the potential implications of these fi ndings in genetic counselling and preventive therapy.