Dataset Information

The prevalence and distribution of the amyloidogenic transthyretin (TTR) V122I allele in Africa.

ABSTRACT: Transthyretin (TTR) pV142I (rs76992529-A) is one of the 113 variants in the human TTR gene associated with systemic amyloidosis. It results from a G to A transition at a CG dinucleotide in the codon for amino acid 122 of the mature protein (TTR V122I). The allele frequency is 0.0173 in African Americans.PCR-based assays to genotype 2767 DNA samples obtained from participants in genetic studies from various African populations supplemented with sequencing data from 529 samples within the 1000 Genomes Project.The rs76992529-A variant allele was most prevalent (allele frequency 0.0253) in the contiguous West African countries of Sierra Leone, Guinea, Ivory Coast, Burkina Faso, Ghana, and Nigeria. In other African countries, the mean allele frequency was 0.011.Our data are consistent with a small number of founder carriers of the amyloidogenic TTR V122I (p.Val142Ile) allele in southern West Africa, with no apparent advantage or disadvantage of an allele carrying newborn reaching adulthood. In U.S. African Americans, the allele represents a significant risk for congestive heart failure late in life. If clinical penetrance is similar in African countries with high allele frequencies, then cardiac amyloidosis could also represent a significant cause of heart disease in the elderly in those populations.

SUBMITTER: Jacobson DR

PROVIDER: S-EPMC5023940 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature

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The prevalence and distribution of the amyloidogenic transthyretin (TTR) V122I allele in Africa.

Jacobson Daniel R DR Alexander Alice A AA Tagoe Clement C Garvey W T WT Williams Scott M SM Tishkoff Sara S Modiano David D Sirima Sodiomon B SB Kalidi Issa I Toure Amadou A Buxbaum Joel N JN

Molecular genetics & genomic medicine 20160714 5

<h4>Background</h4>Transthyretin (TTR) pV142I (rs76992529-A) is one of the 113 variants in the human TTR gene associated with systemic amyloidosis. It results from a G to A transition at a CG dinucleotide in the codon for amino acid 122 of the mature protein (TTR V122I). The allele frequency is 0.0173 in African Americans.<h4>Methods</h4>PCR-based assays to genotype 2767 DNA samples obtained from participants in genetic studies from various African populations supplemented with sequencing data f ...[more]

PMID: 27652282

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Project description:BackgroundLong-term data on cardiovascular disease (CVD) and mortality in female carriers of the transthyretin (TTR) V122I (pV142I) variant, one of the most common variants of hereditary transthyretin cardiac amyloidosis, are sparse and the effects of blood pressure, heart rate, body mass index, and physical activity on CVD outcomes remain largely unknown.ObjectivesThe aim was to first examine the relationship of TTR V122I (pV142I) carrier status with CVD and mortality and second to investigate the effects of blood pressure, heart rate, body mass index, and physical activity in a large cohort of postmenopausal women.MethodsThe study population consisted of 9,862 non-Hispanic Black/African American women, 9,529 noncarriers and 333 TTR V122I carriers, enrolled in the Women's Health Initiative at 40 centers in the United States. Women were generally healthy and postmenopausal at the time of enrollment (1993-1998). CVD was defined as a composite endpoint consisting of coronary heart disease, stroke, acute heart failure or CVD death, and all-cause mortality. CVD cases were based on self-reported annual mailed health updates. All information was centrally adjudicated by trained physicians. HRs and 95% CIs were obtained from adjusted Cox proportional hazards models.ResultsAmong 9,862 Black female participants (mean age: 62 years [IQR: 56-67 years]), the population frequency of the TTR V122I variant was 3.4% (333 variant carriers and 9,529 noncarriers). During a mean follow-up of 16.1 years (IQR: 9.7-22.2 years), incident CVD occurred in 2,229 noncarriers and 96 carriers, whereas 2,689 noncarriers and 108 carriers died. In adjusted models including demographic, lifestyle, and medical history covariates, TTR V122I carriers were at higher risk of the composite endpoint CVD (HR: 1.52; 95% CI: 1.22-1.88), acute heart failure (HR: 2.21; 95% CI: 1.53-3.18), coronary heart disease (HR: 1.80; 95% CI: 1.30-2.47), CVD death (HR: 1.70; 95% CI: 1.26-2.30), and all-cause mortality (HR: 1.28; 95% CI: 1.04-1.56). The authors found a significant interaction by age but not by blood pressure, heart rate, body mass index, or physical activity.ConclusionsBlack female TTR V122I (pV142I) carriers have a higher CVD and all-cause mortality risk compared to noncarriers. In case of clinical suspicion of amyloidosis, they should be screened for TTR V122I (pV142I) carrier status to ensure early treatment onset.

Project description:BackgroundTTR (transthyretin) cardiac amyloidosis is caused by dissociation of TTR into monomers, which misassemble into amyloid fibrils. TTR stabilizers act at the dimer-dimer interface to prevent dissociation. We investigated differences in survival among patients with TTR cardiac amyloidosis on stabilizer medications compared with those not on stabilizers.Methods and resultsA retrospective study of patients with TTR cardiac amyloidosis presenting to a single center was conducted. Baseline characteristics were compared between those treated with stabilizers and those not treated with stabilizers. Cox proportional hazards modeling assessed for univariate predictors of the composite outcome of death or orthotopic heart transplant (OHT). Multivariable Cox proportional hazards assessed whether stabilizer treatment was independently associated with improved death or OHT after controlling for significant univariate predictors. One hundred twenty patients (mean age, 75±8, 88% male) were included: 29 patients who received stabilizers and 91 patients who did not. Stabilizer use was associated with a lower risk of the combined end point of death or OHT (hazard ratio, 0.32; 95% confidence interval, 0.18-0.58; P<0.0001). Subjects treated with stabilizers were more likely to be of White race (93% versus 55%; P<0.001), classified as New York Heart Association classes I and II (79% versus 38%; P=0.002), less likely to have a mutation (10% versus 36%; P=0.010), have lower troponin I (median 0.06 versus 0.12 ng/mL; P=0.002), and higher left ventricular ejection fraction (49% versus 40%; P=0.011), suggesting earlier stage of disease. In multivariable Cox analysis, the association between stabilizer and death or OHT persisted when adjusted for all noncollinear univariate predictors with P<0.05 (hazard ratio, 0.37; 95% confidence interval, 0.19-0.75; P=0.003).ConclusionsTTR stabilizers are associated with decreased death and OHT in TTR cardiac amyloidosis. These results need to be confirmed by ongoing randomized clinical trials.

Dataset Information

The prevalence and distribution of the amyloidogenic transthyretin (TTR) V122I allele in Africa.

Publications

The prevalence and distribution of the amyloidogenic transthyretin (TTR) V122I allele in Africa.

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