A genealogical and clinical study of the phenotypical variation within the Swedish transthyretin His88Arg (p. His108Arg) amyloidosis family.

UNLABELLED: In 2005 we reported the first case of transthyretin His88Arg (p. His108Arg) amyloidosis, a mutation characterised by cardiomyopathy. Six additional gene carriers of whom five have clinical symptoms of disease have now been identified in Sweden, and we have been able to identify a possible founder and to characterise the Swedish phenotype of the transthyretin (TTR) His88Arg mutation. Genealogical studies of church records were used to identify the individuals with the disease and their families. Routine clinical investigations of neurological and heart manifestation of the disease were utilised. We found that genealogically all seven individuals were related and originated from the same region in Sweden. Amyloid deposits were demonstrated in biopsies and the TTR His88Arg mutation was identified in all patients. Patients had a late onset disease (≥ 50 years of age) and all exhibited a severe amyloid cardiomyopathy. A pronounced peripheral axonal neuropathy was with certainty demonstrated in one patient only, who also was operated for a magnetic resonance confirmed spinal stenosis, however, without any effect on his neurological symptoms. Five of the patients had carpal tunnel syndrome. The first reported case is now deceased from cardiac failure. One patient has had a sequential heart and liver transplantation. One gene carrier had no symptoms or findings of disease on latest evaluation at the age of 44. IN CONCLUSION: the Swedish TTRHis88Arg patients all have a common Swedish founder. Cardiomyopathy with heart failure, as well as carpal tunnel syndrome and spinal stenosis were early signs of disease; but peripheral neuropathy was present in one patient before symptoms of cardiomyopathy so the phenotypical presentation of this mutation is variable.

A randomized trial of genotype-guided dosing of warfarin.

BACKGROUND: The level of anticoagulation in response to a fixed-dose regimen of warfarin is difficult to predict during the initiation of therapy. We prospectively compared the effect of genotype-guided dosing with that of standard dosing on anticoagulation control in patients starting warfarin therapy. METHODS: We conducted a multicenter, randomized, controlled trial involving patients with atrial fibrillation or venous thromboembolism. Genotyping for CYP2C9*2, CYP2C9*3, and VKORC1 (-1639G→A) was performed with the use of a point-of-care test. For patients assigned to the genotype-guided group, warfarin doses were prescribed according to pharmacogenetic-based algorithms for the first 5 days. Patients in the control (standard dosing) group received a 3-day loading-dose regimen. After the initiation period, the treatment of all patients was managed according to routine clinical practice. The primary outcome measure was the percentage of time in the therapeutic range of 2.0 to 3.0 for the international normalized ratio (INR) during the first 12 weeks after warfarin initiation. RESULTS: A total of 455 patients were recruited, with 227 randomly assigned to the genotype-guided group and 228 assigned to the control group. The mean percentage of time in the therapeutic range was 67.4% in the genotype-guided group as compared with 60.3% in the control group (adjusted difference, 7.0 percentage points; 95% confidence interval, 3.3 to 10.6; P<0.001). There were significantly fewer incidences of excessive anticoagulation (INR ≥4.0) in the genotype-guided group. The median time to reach a therapeutic INR was 21 days in the genotype-guided group as compared with 29 days in the control group (P<0.001). CONCLUSIONS: Pharmacogenetic-based dosing was associated with a higher percentage of time in the therapeutic INR range than was standard dosing during the initiation of warfarin therapy. (Funded by the European Commission Seventh Framework Programme and others; ClinicalTrials.gov number, NCT01119300.).

Cardiomyopathy in Swedish patients with the Gly53Glu and His88Arg transthyretin variants.

We report two new amyloidogenic transthyretin (TTR) variants detected in the Swedish population. One variant was previously unknown, while the other has been described in a French family. In Swedish patients, both variants have caused late-onset cardiac amyloidosis characterised by heart failure. In both cases, the diagnosis was determined by the detection of amyloid deposits in skin and/or rectal biopsies and identification of TTR mutations by genetic analysis. The index case of the previously unknown mutation (ATTR His88Arg) was a 66-year-old Swedish man, who sought medical attention for increasing dyspnea. Echocardiographic examination disclosed a restrictive cardiomyopathy, and subsequent examinations disclosed TTR amyloidosis. The patient is alive with moderate symptoms one year after the onset of disease. The index case for the new Swedish mutation (ATTR Gly53Glu) is a woman who sought medical attention at the age of 57 because of increasing dyspnea. Echocardiographic examination disclosed a hypertrophic cardiomyopathy with diastolic impairment. The diagnosis of systemic amyloidosis was made by fat aspiration biopsy and histopathology. The patient developed severe intractable heart failure, with pulmonary effusion and ascites. She died four years after the onset of her disease of intractable heart and kidney failure. Post mortem examination of biopsy specimens and blood revealed TTR amyloid deposits and the ATTR Gly53Glu mutation was detected.