| 1. |
- Alarcon, Flora, et al.
(författare)
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Non-parametric estimation of survival in age-dependent genetic disease and application to the transthyretin-related hereditary amyloidosis
- 2018
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Ingår i: PLOS ONE. - : Public Library Science. - 1932-6203. ; 13:9
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Tidskriftsartikel (refereegranskat)abstract
- In genetic diseases with variable age of onset, survival function estimation for the mutation carriers as well as estimation of the modifying factors effects are essential to provide individual risk assessment, both for mutation carriers management and prevention strategies. In practice, this survival function is classically estimated from pedigrees data where most genotypes are unobserved. In this article, we present a unifying Expectation-Maximization (EM) framework combining probabilistic computations in Bayesian networks with standard statistical survival procedures in order to provide mutation carrier survival estimates. The proposed approach allows to obtain previously published parametric estimates (e.g. Weibull survival) as particular cases as well as more general Kaplan-Meier non-parametric estimates, which is the main contribution. Note that covariates can also be taken into account using a proportional hazard model. The whole methodology is both validated on simulated data and applied to family samples with transthyretin-related hereditary amyloidosis (a rare autosomal dominant disease with highly variable age of onset), showing very promising results.
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| 2. |
- Gorram, Farida, et al.
(författare)
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New data on the genetic profile and penetrance of hereditary Val30Met transthyretin amyloidosis in Sweden
- 2021
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Ingår i: Amyloid. - : Taylor & Francis. - 1350-6129 .- 1744-2818. ; 28:2, s. 84-90
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Hereditary transthyretin (ATTRv) amyloidosis is of autosomal dominant transmission, caused by a spectrum of mutations in the transthyretin (TTR) gene. The ATTRV30M (p.Val50Met) is the most frequent substitution in Europe. Northern Sweden is a known cluster for ATTRV30M amyloidosis patients due to high prevalence of the mutation rate, with homozygous cases. First symptoms occur generally during the 6th decade. Previous studies reported low penetrance in this area and possible anticipation in families. In order to refine our knowledge of the genetic aspects, penetrance and factors that influence the disease’s risk, we performed a comprehensive study of ATTRV30M families in Sweden.Methods: To assess anticipation, well-established age at onset (AO) was compared in all informative parent-offspring pairs and in subgroups, after excluding ascertainment biases. Penetrance was estimated using a non-parametric method that enables to study covariates’ effect on the disease’s risk.Results: We analysed 114 ATTRV30M Swedish families, including 12 homozygous individuals. Among 131 parent-offspring pairs, we found an average anticipation of 11.7 [Standard Deviation (SD) =10.03] years, higher in case of maternal transmission (mean ± SD = 13.7 ± 8.4 years), compared to paternal transmission (mean ± SD = 7.9 ± 11.5 years, p < .003). Anticipation remained significant, after exclusion of ascertainment biases. In heterozygous ATTRV30M kindred, penetrance was low, estimated below 10% [95% confidence interval (CI) = 6–10] at 40 years-old, increasing to 71% [95% CI= 65–76] at age 90 years. The risk was found to be higher in male patients (p < .01) and in case of maternal transmission (p < .01), reflecting a parent of origin effect. We observed no difference of penetrance according the geographical origin. Finally, the disease risk was similar in heterozygous and homozygous ATTRV30M amyloidosis individuals.Conclusions: Our study provides new data on the genetics of ATTRV30M families in Sweden, including the occurrence of anticipation and on penetrance. Both are increased in case of maternal inheritance and in male patients. Overall, gender seems to be a factor that substantially modulates the AO of the disease, in this area. Clinically, these findings are of importance to guide the management of sibships and the monitoring of mutation carriers.
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| 3. |
- Gorram, Farida, et al.
(författare)
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Variation of Penetrance estimates in a wide spectrum of TTR-FAP families : implication for management of carriers
- 2018
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Ingår i: Neurology. - : Lippincott Williams & Wilkins. - 0028-3878 .- 1526-632X. ; 90
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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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| 4. |
- Planté-Bordeneuve, Violaine, et al.
(författare)
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A multicentric study of the disease risks and first manifestations in Hereditary transthyretin amyloidosis (ATTRv) : insights for an earlier diagnosis
- 2023
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Ingår i: Amyloid. - : Taylor & Francis. - 1350-6129 .- 1744-2818. ; 30:3, s. 313-320
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Tidskriftsartikel (refereegranskat)abstract
- Background: In hereditary transthyretin amyloidosis (ATTRv), early manifestation and age at onset (AO) may vary strikingly. We assessed the disease’risk (penetrance), AO and initial features in ATTRv families to gain insights on the early disease presentation. Methods: Genealogical information, AO and first disease manifestations were collected in ATTRv families, from Sweden, Italy (Sicily), Spain (Mallorca), France, Turkey, Brazil. Penetrance was computed using a non-parametric survival method. Results: We analysed 258 TTRV30M kindreds and 84 carrying six other variants (TTRT49A, F64L, S77Y, S77F, E89Q, I107V). In ATTRV30M families, the earliest disease risk was found at age 20 years in the Portuguese and Mallorcan families and at age 30-35 years, in the French and Swedish groups. The risks were higher in men and in carriers of maternal descent. In families carrying TTR-nonV30M variants, the earliest disease risk ranged from 30 y-o in TTRT49A to 55 y-o in TTRI107V families. Peripheral neuropathy symptoms were the most frequent initial manifestations. Among patients carrying TTRnonV30M variants, about 25% had an initial cardiac phenotype, one third a mixed phenotype. Conclusion: Our work provided solid data on the risks and early features of ATTRv in a spectrum of families to enhance an early diagnosis and treatment.
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