Ser77Tyr transthyretin amyloidosis in Israel: Initial manifestations and diagnostic features

Abstract

Objective: Amyloidosis due to the transthyretin Ser77Tyr mutation (ATTRS77Y) is a rare autosomal-dominant disorder, characterized by carpal-tunnel syndrome, poly- and autonomic-neuropathy, and cardiomyopathy. However, related symptoms and signs are often nonspecific and confirmatory tests are required. We describe the age and frequency of early symptoms and diagnostic features among individuals of Jewish Yemenite descent in Israel.

Methods: Records of mutation carriers were retrospectively reviewed. ATTRS77Y diagnosis was defined by the presence of amyloid in tissue and/or amyloid-related cardiomyopathy.

Results: We identified the Ser77Tyr mutation at the heterozygous state in 19 amyloidosis patients (mean age at diagnosis: 62 ± 5.7 years, range 49-70) and 30 amyloid-negative carriers. The probability for disease diagnosis increased from 4.4% at age 49 to 100% at 70 and occurred earlier in males. Initial symptoms preceded diagnosis by 5 ± 3.8 years (range 0-12) and were commonly sensory changes in the extremities. Erectile dysfunction predated these in 8/13 (62%) males. In two patients cardiac preceded neurological symptoms. Two patients declined symptoms. Electrophysiological studies near the time of diagnosis indicated a median neuropathy at the wrist in 18/19 (95%) and polyneuropathy in 13/19 (68%). Skin biopsy revealed epidermal denervation in 15/16 (94%) patients. Cardiomyopathy was identified in 16/19 (84%). Sensory complaints or epidermal denervations were present in 17/30 (57%) of amyloid-negative carriers and co-occurred in 10/30 (33%).

Interpretation: ATTRS77Y symptoms commonly occur after age 50, but may begin earlier. Median neuropathy, skin denervation and cardiomyopathy are frequently identified. Symptoms may be absent in patients and common in amyloid-negative carriers.

Figure 1

Skin denervation and amyloid in the deep dermis of skin biopsies. Immunofluorescent staining of PGP9.5 shows normal IENFD in a healthy volunteer (A) and low IENFD in a patient without clinical complaints, case 1 (B). Amyloid deposits visualized by Congo red stain in the deep dermis of case 1 (C–F) and in another patient which had no clinical symptoms, case 6 (G–K). Congo red–positive deposits (arrowheads) of amyloid by light microscopy (C, D, G, and J) are birefringent under polarized light (E, H, and K), and enhanced by red spectral fluorescence (F and I). Inset in C refers to D–F, and inset in G to J and K. Scale bars: A and B, 20 μm; C, G, H, and I, 200 μm; D–F, 100 μm; J and K, 50 μm.

Figure 2

False negative ^99mTc‐DPD bone scan images (Perugini grade 1) in a 67 y.o. patient with ATTRS77Y cardiomyopathy (case 3). Anterior (A and C) and posterior (B and D) body images of early (A and B) and delayed (3 h; C and D) scans are shown. At the time of evaluation, the patient had NYHA III heart failure. Maximal left ventricular wall thickness was 15 mm by echocardiography and 25 mm by cardiac MR. The insert (E) illustrates reduced left ventricular longitudinal strain (average − 8) with apical sparing which is typical for amyloidosis. Note uptake in transplanted right kidney.

Figure 3

(A) Age distribution of patients at diagnosis and amyloid‐negative carriers at evaluation. (B) Survival analysis for predicting age at diagnosis. Males (n = 13) were diagnosed as affected earlier, at a median onset of 62 years, while women (n = 6) were at 68 years (p = 0.0076). ****p < 0.0001.