Epidemiological, clinical and genetic study of familial amyloidotic polyneuropathy in Cyprus

Objectives. To define the incidence and prevalence of familial amyloidotic polyneuropathy (FAP) TTRVal30Met on the island of Cyprus. To study the clinical phenotype and genetic features of FAP TTRVal30Met in the Cypriot population. Methods. The clinical and neurogenetic databases were used to identify probands with FAP TTRVal30Met and detailed family trees were constructed. Potential carriers of the mutation were identified from the family trees and assessed clinically and genetically. Transthyretin was completely sequenced in patients and potential carriers. Results. Thirty-six patients carrying the TTRVal30Met mutation (one homozygote) from 22 families were identified. On 1 December 2003 the prevalence of FAP was 3.72/100,000 while the incidence is estimated to be 0.69/100,000 per year. The phenotype observed was characteristic for a length dependent sensorimotor and autonomic neuropathy with neuropathic pain. Mean age of onset was 46 years. Penetrance is estimated to be 28% and positive anticipation in the age of onset is found. Conclusion. FAP is relatively prevalent in Cyprus which may be considered as another endemic focus of the disease in Europe. The mean age of onset and penetrance is different from the Portuguese and Swedish populations. Understanding the biological factors that determine these differences could potentially lead to therapeutic advances.