Isotopic analysis of Cu in serum samples for diagnosis of Wilson's disease: a pilot study

Abstract

Wilson's disease (WD) is a genetic disorder affecting Cu metabolism, which can lead to severe physiological and neurological symptoms, and even death if untreated. Based on the fact that WD patients show low Cu levels in serum, implementation of screening programs for diagnosis of this condition at the moment of birth, when progression of the disease can be still arrested, has been attempted in the past. These attempts, however, have been unsuccessful, as healthy new-borns often show low Cu levels in serum due to liver immaturity. In this work, the potential use of isotopic analysis of Cu in serum samples as an alternative diagnostic parameter for Wilson's disease has been investigated. For this purpose, the Cu isotopic composition of a set of serum samples from different groups showing either low (i.e. WD patients, patients who had undergone bariatric surgery, infants) or normal (supposedly healthy adults) Cu concentration levels was determined by means of multi-collector ICP-mass spectrometry (MC-ICP-MS), after chromatographic isolation of Cu. For this purpose, AG-MP-1 strong anion exchange resin was relied upon, enabling quantitative recovery of Cu in pure form from the serum samples. MC-ICP-MS measuring conditions were optimized to avoid the influence of spectral overlap, and Ni was admixed as an internal standard for correction of instrumental mass discrimination. The use of this optimized method provided delta Cu-65 for the serum samples with a typical analytical uncertainty of similar to 0.20 parts per thousand (k = 2). Our results show that, for the population considered in this study, combination of Cu concentration values and Cu isotopic information allows classification of WD patients, infants and controls into different groups, while the use of concentration values only is not sufficient for this purpose. Although further studies with a larger number of samples are needed, results are encouraging as far as the use of Cu isotopic analysis for early diagnosis of Wilson's disease is concerned

Current Role of ICP–MS in Clinical Toxicology and Forensic Toxicology: A Metallic Profile

“…• 65 Cu and 63 Cu isotopes were measured by the same group in dried urine spots [79] and in serum [80] samples from WD patients, a genetic disorder in which copper accumulates in tissues, which can lead to death if not treated. After separation with a strong anion exchange resin the isotopes were measured by MC-ICP-MS, a technique of choice for isotopic fractionation.…”

Evidence of isotopic fractionation of natural uranium in cultured human cells

“…Isotopic fractionation measurements have been identified as new biomarkers for the investigation of metabolic processes (2-6) and as powerful tools for the early detection of diseases (7)(8)(9)(10)(11)(12). Studies of Cu and Zn isotopic fractionation are very promising for the early diagnosis of different types of cancer (9,12) and neurodegenerative diseases (8,13), whereas Fe and Ca isotopic fractionation measurements have shown their ability to monitor Fe absorption efficiency (3) and bone mineral balance (7), respectively. Concerning high-mass elements, only a few in vivo studies have been reported, within the framework of toxicity investigations and identification of contamination sources, that seem to suggest that isotopic fractionation occurs during metabolic processes for elements such as Pb and Hg (14)(15)(16).…”

“…The isotopic fractionation of medium-mass endogen elements (i.e., Ca, Fe, Cu, and Zn) has recently been shown to have an outstanding potential for biomedical applications (1). Isotopic fractionation measurements have been identified as new biomarkers for the investigation of metabolic processes (2-6) and as powerful tools for the early detection of diseases (7)(8)(9)(10)(11)(12). Studies of Cu and Zn isotopic fractionation are very promising for the early diagnosis of different types of cancer (9,12) and neurodegenerative diseases (8,13), whereas Fe and Ca isotopic fractionation measurements have shown their ability to monitor Fe absorption efficiency (3) and bone mineral balance (7), respectively.…”

Natural variations of copper and sulfur stable isotopes in blood of hepatocellular carcinoma patients

“…The natural variations of the isotopic ratios of an element offers a new means to study the imbalances linked to pathological conditions (16)(17)(18). Here, we used the natural variations of the …”