RESUMEN
Graves' disease (GD) is associated with HLA-DR3 (DRB1*03) in Caucasians, but the exact amino-acid sequence in the DR beta1 chain conferring susceptibility to GD is unknown. Therefore, the aim of our study was to identify the critical sequence among the HLA-DRB1 amino-acid residues occupying the peptide-binding pocket, which conferred susceptibility to GD. We sequenced the HLA-DRB1 locus in 208 Caucasian GD patients and 149 Caucasian controls. Sequence analysis showed an increased frequency of DR beta-Arg-74 in GD patients compared to controls (41.8 and 13.4%, respectively; P=2.3 x 10(-8), OR=4.6). Moreover, subset analyses showed that DR beta-Arg-74 was also significantly more frequent in the HLA-DR3 negative GD patients than in controls (7.6 vs 0.8%, P=0.02, OR=10.5), suggesting that the association with DR beta-Arg-74 is independent of the association with HLA-DR3. Structural modeling studies demonstrated that the change at position 74 from the neutral amino acids Ala or Gln to the positively charged amino-acid Arg significantly modifies the three-dimensional structure of the DR peptide-binding pocket. Our results suggested that structural heterogeneity of the DR beta-chain peptide-binding pocket P4 at residue 74 predispose some at risk individuals to GD.
Asunto(s)
Alelos , Arginina/genética , Predisposición Genética a la Enfermedad , Enfermedad de Graves/genética , Antígenos HLA-DR/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Arginina/química , Estudios de Casos y Controles , Femenino , Frecuencia de los Genes , Enfermedad de Graves/epidemiología , Cadenas HLA-DRB1 , Humanos , Masculino , Persona de Mediana Edad , Reacción en Cadena de la Polimerasa , Población BlancaRESUMEN
Radioimmunoassay for conjugated and free estrone (E1), estradiol-17beta(E2) and estriol (E3) in male plasma was investigated, while no precise determination of conjugated estrogen in male plasma had been established. Each tritiated estrogen glucuronides for determining the recovery was added to 3 ml of plasma samples. These plasma samples were extracted with acetone, hydrolyzed with 15 vol% HCl at 100 degrees C for 60 minutes, and resulting free estrogens were extracted with ether. These extracts were washed with 1% NaOH and 1% NaHCO3, and applied to microcolumn of Sephadex LH-20. Then they were determined by the radioimmunoassay as the same method of evaluation for free estrogen. Each mean values of plasma free and conjugated estrogen in 10 normal adult males was as follows: 36.0 +/- 9.81 pg/ml(free E1), 29.5 +/- 11.0 pg/ml(free E2), 1.80 +/- 1.27 pg/ml (free E3), 31.0 +/- 12.6 pg/ml (conjugated E1), 36.0 +/- 14.2 pg/ml (conjugated E2), 30.6 +/- 8.35 pg/ml (conjugated E3). Conjugated estrogen to free estrogen ratio was 1.45.