Wide metabolite coverage LC-MS/MS assay for the diagnosis of inherited metabolic disorders in urine

OBJECTIVE

The laboratory diagnosis of inherited metabolic disorders (IMD) has undergone significant development in recent decades, mainly due to the use of mass spectrometry, which allows rapid multicomponent analysis of a wide range of metabolites. Combined with advanced software tools, the diagnosis becomes more efficient as a benefit for both physicians and patients.

METHODS

A hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry assay for determination of urinary purines, pyrimidines, N-acylglycines, N-acetylated amino acids, sugars, sugar alcohols and other diagnostically important biomarkers was developed and validated. Evaluation of the results consisting of utilisation of robust scaling and advanced visualization tools is simple and even suitable for urgent requirements.

RESULTS

The developed method, covering 65 biomarkers, provides a comprehensive diagnostic platform for 51 IMD. For most analytes, linearity with R2 > 0.99, intra and inter-day accuracy between 80 and 120 % and precision lower than 20 % were achieved. Diagnostic workflow was evaluated on 47 patients and External Quality Assurance samples involving a total of 24 different IMD. Over seven years, more than 2300 urine samples from patients suspected for IMD have been routinely analysed.

CONCLUSIONS

This method offers the advantage of a broad coverage of intermediate metabolites of interest and therefore may be a potential alternative and simplification for clinical laboratories that use multiple methods for screening these markers.

Free triiodothyronine/free thyroxine (FT3/FT4) ratio is strongly associated with insulin resistance in euthyroid and hypothyroid adults: a cross-sectional study

INTRODUCTION

Insulin resistance (IR) is a key and early pathogenetic mechanism of cardiometabolic diseases with huge potential if detected early and mitigated, for lowering the burden of the disease. Available data are conflicting to what extent adult thyroid dysfunction is associated with IR. Therefore, we aimed to investigate the association and to identify which thyroid parameters are predictors of IR.

MATERIAL AND METHODS

After undergoing basic anthropometric and biochemical studies including thyroid hormones, oral glucose tolerance test (OGTT), and insulin, 1425 middle-aged individuals were divided into three groups according to thyroid parameters: overt hypothyroidism (OH), subclinical hypothyroidism (SH), and euthyroidism (EU).

RESULTS

The homeostasis model assessment of IR (HOMA-IR), fasting insulin, and two-hour glucose levels of OGTT showed a steady, yet insignificant, increase from EU through SH to OH. The strongest noted correlations were those of insulin levels with free triiodothyronine/free thyroxine (FT3/FT4) ratio (r = 0.206, p < 0.001) and FT3 (r = 0.205, p < 0.001). Also in the case of HOMA-IR, the only statistically significant correlations were observed for FT3 (r = 0.181, p < 0.001) and the FT3/FT4 ratio (r = 0.165, p < 0.001). Among other thyroid hormones, linear logistic regression proved the FT3/FT4 ratio as the only significant predictor of HOMA-IR (linear coefficient = 5.26, p = 0.027) and insulin levels (linear coefficient = 18.01, p = 0.023), respectively. Thyroid-stimulating hormone was not associated with IR in either correlation or regression analysis.

CONCLUSIONS

The FT3/FT4 ratio should be more emphasised in the diagnosis and treatment of thyroid disorders. Patients could benefit from a pharmacological reduction of the FT3/FT4 ratio, potentially leading to a decrease in insulin resistance, and thus a corresponding decrease in the risk of the cardiometabolic diseases.

Analysis of ERBB2 and TOP2A gene status using fluorescence in situ hybridization versus immunohistochemistry in localized breast cancer

The aim of our study was to assess the ERBB2 and TOP2A gene status in breast carcinoma tissue using fluorescence in situ hybridization (FISH) and to compare their amplification with immunohistochemistry assay (IHC) of the ERBB2, resp. topoisomerase IIalpha proteins. TOP2A status is important in tailored treatment as topoisomerase IIalpha is the molecular target for topoisomerase IIalpha inhibitors. This study was conducted to determine whether the methods are equivalent in their assessment of TOP2A status and to correlate the genetic findings with basic tumor and disease characteristics. Locus specific ERBB2, TOP2A genes and chromosome 17 centromeres (CEP17) probes were hybridized to 72 formalin-fixed paraffin-embedded (FFPE) tissue samples from patients with non-metastatic breast carcinoma (M0). The ERBB2, TOP2A and CEP17 signals were counted and gene numbers per nucleus or per CEP17 were calculated, respectively. Sections were also stained with commercial polyclonal antibody (HercepTestTM), anti-topoisomerase IIalpha monoclonal antibody (clone SWT3D1) and scored for the presence of membrane/nuclear staining. ERBB2 amplification was found in 20.3%, ERBB2 and TOP2A co-amplification was detected in 14.5% of cases. Deletion of the ERBB2/TOP2A gene was found in 1.4/2.8% of sections, respectively. Concordance of FISH and IHC techniques in the evaluation of ERBB2 and TOP2A status was found in 88.4% and 66.7%, respectively. The low concordance of FISH versus IHC in the evaluation of TOP2A status was mainly due to the presence of TOP2A amplified tumors in IHC negative or weakly positive specimens. Topoisomerase IIalpha expression was increased in bigger tumors, although direct correlation with tumor grading was not found. ERBB2 amplification was found in more aggressive breast cancers with grades 2 and 3, respectively. Interestingly, chromosome 17 polysomy was more frequently observed among older women (>55 years), suffering usually from less aggressive disease. Our results confirm the high concordance of the ERBB2 and TOP2A gene co-amplification in breast carcinoma. Differences between FISH and IHC in the case of ERBB2 gene status were found only in IHC 2+ sections as reported in the literature. However, our study points to the importance of FISH examination of TOP2A gene status in all tumors with ERBB2 amplification.