Variation of Penetrance estimates in a wide spectrum of TTR-FAP families : implication for management of carriers

• Objective: Refine estimation of penetrance in TTR-FAP families, unravelling the role of covariates. Background: TTR-FAP is an autosomal dominant neuropathy caused by mutations in the TTR gene. Recently, therapeutic advances including gene modifying approaches proved effective to halt disease progression. Val30Met, the most common variant in Portugal and Latin America is associated to age at onset (AO) below 50 y-o. In Western Europe, US, Japan, heterogeneity of TTR variants is associated to AO above 50 y-o, a mixed polyneuropathy and cardiomyopathy. Determining the risk of being affected (penetrance) is essential to guide gene carrier management.Design/Methods: NPSE is a non-parametric method developed to estimate penetrance, taking into account covariates. Genealogical data from 227 kindreds were collected. There were 92 Val30Met families from Sweden, 64 Val30Met from Portugal and 73 from France including 37 Val30Met and 36 families carrying other TTR variants frequently identified: Ser77Tyr (15), Ile107Val (12), Ser77Phe (9).Results: We found highly significant differences of penetrance between Val30Met families from various origins. Risk estimates also differed between the TTR variants (French Val30Met, Ser77Tyr, Ile107Val, Ser77Phe) (p < 0.004). In the French and Swedish Val30Met families, the disease risk remained below 10% until age 40 years then increased to 72% and 63% at 80 years, respectively. In Portuguese families, the risk was above 20% from age 30 years then up to 92% at 80 y-o. In Ile107Val, Ser77Tyr and Ser77Phe families the risk was virtually null until 50 years of age and raised to 54%, 70%, and 86% at age 80 years, respectively. A higher risk is observed when the disease is maternally inherited in Portuguese and Swedish kindreds (p <0.001).Conclusions: Important variation of penetrance is observed in TTR-FAP families according covariates. Such data will help for management of gene carriers, allowing early diagnosis and therapeutic initiation timely.

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MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Neurologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Neurology (hsv//eng)

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