P-PN022. Transthyretin familial amyloid polyneuropathy in multi-ethnic Malaysians

Introduction. Familial amyloid polyneuropathy (FAP) is a rare autosomal dominant peripheral neuropathy. We report a case series of Malaysian FAP patients. Methods. Patients with definite (genetically confirmed) FAP seen at the University of Malaya Medical Centre between 2008 till 2019 were included in the series. The patients’ demographic and clinical features and investigations including nerve conduction studies and electromyography (NCS/EMG), echocardiography, sural nerve biopsy and hATTR mutation are reported. Results. A total 21 index cases were seen. Nineteen (90%) were ethnic Chinese, one ethnic (5%) Malay and one (5%) ethnic Indian; Fourteen (67%) were men. Mean age of onset of symptoms was 56.1 ± 10.5 years (range: 31-73). Nineteen (90%) patients presented with numbness and weakness of the limbs while two had postural hypotension. Fifteen (71%) patients had positive family history. NCS/EMG showed sensorimotor polyneuropathy in 19 (90%) patients; fifteen (71%) showing axonal neuropathy. Amyloid deposits were seen on nerve biopsy in ten patients and rectal, leptomeningeal and endomyocardial biopsies in 1 patient respectively. The latter was diagnosed as familial amyloid cardiomyopathy (FAC). Sixteen patients (76%) had abnormal cardiac echocardiogram with amyloid deposits. Fifteen Chinese patients (71%) carried the Ala97Ser hATTR mutation while the FAC patient has Asp39Val mutation. Our Malay patient had Glu54Lys mutation and Indian patient had Gly67Val mutation. Two patients carried Val30Met mutation. Autonomic function test was abnormal in all 7 patients in whom they were carried out. Conclusion. FAP in Malaysians is seen mainly among ethnic Chinese, in whom Ala97Ser may be a common mutation. This is also the reported “hotspot” mutation for FAP reported in Taiwan but not in China. Similar to Taiwan, Chinese-Malaysians are descended from immigrants from Southern China. Similar to Taiwanese patients, our FAP patients with Ala97Ser mutation, present with late-onset progressive sensorimotor polyneuropathy and cardiac involvement was common.