Expanding the spectrum of transthyretin amyloidosis

Abstract

Transthyretin (TTR) is one of the proteins that may cause amyloidosis. 1 Although TTR is synthesized mainly in the liver, it is also produced at other sites, such as the choroid plexus in the brain and the retinal pigment epithelium in the eye. 2 Transthyretin produced in the liver is responsible for the major manifestations of amyloidogenic transthyretin (ATTR) amyloidosis, such as neuropathy and cardiomyopathy, whereas TTR produced in the choroid plexus and the retinal pigment epithelium causes oculoleptomeningeal amyloidosis. 1 Amyloidosis caused by TTR deposition (ie, ATTR amyloidosis) is divided into two types: the first occurs in patients without mutation in the TTR gene, and the other occurs in those with a TTR mutation. 2 The former was traditionally known as senile systemic amyloidosis and the latter as familial amyloid polyneuropathy; however, according to recent nomenclature recommendations from the International Society of Amyloidosis, these diseases are designated wild-type ATTR (ATTRwt) amyloidosis and hereditary ATTR (ATTRv; v for variant) amyloidosis, respectively. 3

Transthyretin Amyloidosis: Update on the Clinical Spectrum, Pathogenesis, and Disease-Modifying Therapies

“…Notably, serum creatine kinase levels were normal or only slightly elevated in these patients. This report further expands the spectrum of ATTRwt amyloidosis and increases the need for physicians' awareness of this disease at the time of differential diagnosis of myopathy [16].…”

Case Report: Systemic Amyloidosis Involving the Heart and Skeletal Muscle

“…Among which the AL and ATTRv are the most common types of amyloidosis that affect skeletal muscle ( 6 ). Even so, amyloid myopathy was reported in only 1.5% of patients with AL amyloidosis, which may be related to the fact that Congo red staining was not part of our standard muscle biopsy panel on muscle biopsies ( 13 ). It has been found that routine Congo red staining in all diagnostic muscle biopsies is 10 times more likely to diagnose amyloid myopathy than selective Congo red staining in clinically or pathologically suspicious cases ( 14 ).…”