Metabolomics analysis for diagnosis and biomarker discovery of transthyretin amyloidosis

Untargeted metabolomics is a well-established technique and a powerful tool to find potential plasma biomarkers for early diagnosing hereditary transthyretin amyloidosis. Hereditary transthyretin amyloidosis (ATTRv) is a disabling and fatal disease with different clinical features such as polyneuropathy, cardiomyopathy, different gastrointestinal symptoms and renal failure. Plasma specimens collected from 27 patients with ATTRv (ATTRV30M), 26 asymptomatic TTRV30M carriers and 26 control individuals were subjected to gas chromatography (GC)- and liquid chromatography (LC)-mass spectrometry (MS)-based metabolomics analysis. Partial least squares discriminant and univariate analysis was used to analyse the data. The models constructed by Partial least squares-discriminant analysis (PLS-DA) could clearly discriminate ATTRV30M patients from controls and asymptomatic TTRV30M carriers. In total, 24 plasma metabolites (VIP > 1.0 and p <.05) were significantly altered in ATTRV30M patient group (6 increased and 18 decreased). Eleven of these distinguished the ATTRV30M group from both controls and TTRV30M carriers. Plasma metabolomics analysis revealed marked changes in several pathways in patients with ATTRV30M amyloidosis. Statistical analysis identified a panel of biomarkers that could effectively separate controls/TTRV30M carriers from ATTRV30M patients. These biomarkers can potentially be used to diagnose patients at an early stage of the disease

Enlarged cross-sectional area in peripheral nerves in Swedish patients with hereditary V30M transthyretin amyloidosis

Introduction: In hereditary transthyretin amyloidosis (ATTRv), two different fibrillar forms causing the amyloid deposition, have been identified, displaying substantially cardiac or neuropathic symptoms. Neuropathic symptoms are more frequent in early-onset patients, whereas late-onset patients, besides cardiac symptoms, seem to develop carpal tunnel syndrome, more often. With ultrasonography (US) of peripheral nerves, it is possible to distinguish structural changes, and enlarged cross-sectional area (CSA). The main purpose of this study was, for the first time, to elucidate US of peripheral nerves in Swedish ATTRv patients at an early stage of the disease, and to evaluate possible early enlarged CSA. Material and methods: This prospective study included first visit data of 13 patients, aged 30–88 years, of which 11 with late-onset age. All had a positive V30M mutation. Eight men and six women (aged 28–74 years) served as controls. Results: Significantly enlarged CSA was seen in ATTRv patients for the tibial nerve at the ankle (p =.001), the sural nerve (p <.001), the peroneal nerve at the popliteal fossa (p =.003), and the ulnar nerve at the middle upper arm (p =.007). Conclusion: US of peripheral nerves could be a valuable tool in disease evaluation and could facilitate monitoring of disease progression

Abnormal small bowel motility in patients with hereditary transthyretin amyloidosis

Background: Gastrointestinal complications are common in hereditary transthyretin amyloid (ATTRm) amyloidosis. The underlying mechanisms have not been fully elucidated, and the patients' small bowel function remains largely unexplored. The aim of the present study was to compare the small bowel motility in ATTRm amyloidosis patients with that in non-amyloidosis patient controls. Methods: ATTRm amyloidosis patients undergoing evaluation for liver transplantation were consecutively investigated with 24-hour duodenojejunal manometry (n=19). The somatostatin analogue octreotide was used to induce fasting motility. Patients with age at onset of 50years were defined as late-onset cases. For each patient, three age- and sex-matched patient controls (n=57) were selected from the total pool of investigated patients. Key Results: Manometry was judged as abnormal in 58% of the patients and in 26% of the patient controls (P=.01). Patients displayed significantly more daytime phase III migrating motor complexes than patient controls (median 4 vs 2, P<.01), and had a higher frequency of low-amplitude complexes (16% vs 4%; however, this difference did not reach statistical significance, P=.10). Furthermore, late-onset patients showed a delay in octreotide response (5.4 vs 3.8minutes, P<.01), but this was not observed for early-onset patients or within the control group. Conclusions and Inferences: Patients with ATTRm amyloidosis displayed abnormalities in their small bowel motility more frequently than non-amyloidosis patient controls, and the manometric pattern was probably best consistent with a combined neuromyopathic disorder. The delayed octreotide response in late-onset patients warrants further investigation

Gastric emptying before and after liver transplantation for familial amyloidotic polyneuropathy, Portuguese type (Val30Met)

Liver transplantation is an accepted treatment of familial amyloidotic polyneuropathy (FAP), Portuguese type (Val30Met), and the outcome so far seems promising. Gastric retention with nausea and vomiting are common complications of the disease, and may interfere with immuno-suppression therapy and prolong recovery after liver transplantation. The aim of this study was to assess the frequency of gastric retention in FAP patients and to evaluate the impact liver transplantation has on gastric emptying. Twenty-two patients, who had undergone liver transplantation, and had been re-examined for gastric retention after the procedure, were included in the study. Gastric emptying was recorded by scintigraphy after the ingestion of a 99m-technetium (99mTc)-labelled meal (omelette). The half-time (T50) of the emptying phase was calculated. Gastrointestinal symptoms before and after transplantation were recorded, and the majority of patients were also subjected to an upper endoscopic examination, where the presence of solid residual in the stomach was regarded as consistent with gastric retention. A high frequency of gastric retention was noted among the patients both before and after transplantation, and no significant improvement for the group was noted, even though decreased gastric emptying was noted for patients with a duration of the disease for less that 4 years. Patients who improved their nutritional status after transplantation had a faster gastric emptying than those who deteriorated. From our findings it can be concluded that gastric retention is a common complication of FAP and that gastric emptying in patients with longstanding disease (&gt; or = 4 years) is unchanged after liver transplantation.</p

Self-reported gastrointestinal symptoms are more common in liver transplanted transthyretin amyloidosis patients than in healthy controls and in patients transplanted for end-stage liver disease

Special issue, Supplement 1</p