Hereditary transthyretin amyloidosis in multi-ethnic Malaysians

We report the clinical and genetic characteristics of hereditary transthyretin amyloidosis in the multi-ethnic Malaysian population. Subjects with genetically confirmed transthyretin amyloidosis seen between 2001 till August 2020 were included. There were 30 patients and 14 asymptomatic carriers, of which 26 (59.1%) were men. The majority (86.7%) were ethnic Chinese while two (6.7%) each were Malay and Sri Lankan Tamil ethnicity respectively. Among patients, mean age of symptom-onset was 55.9 ± 9.8 years with mean duration from symptom-onset to diagnosis of 3.2 ± 2.5 years. Common presenting symptoms were sensory symptoms of upper limbs (43.3%), symmetric sensory symptoms of both lower limbs (16.7%) and autonomic symptoms (16.7%). Nerve conduction studies showed sensorimotor polyneuropathy in 25 (83.3%) patients (22, axonal). Abnormal echocardiograms were seen in 24 (80%) patients, although 15 were asymptomatic. Of six different TTR mutations found, Ala97Ser was the commonest, and found exclusively in 84.6% of Chinese patients. Other mutations among Chinese patients were Val30Met, Ala25Thr and Asp39Val. Our Malay and Tamil patients had Glu54Lys and Gly47Val mutations respectively. In conclusion, TTR Ala97Ser is the commonest mutation among ethnic Chinese Malaysians which presented with late-onset progressive sensorimotor polyneuropathy, autonomic dysfunction and subclinical cardiac involvement.