The presence of Gd-IgA1 in the circulation of asymptomatic relatives of IgAN patients (46, 177) as well as in mesangial deposits in individuals without clinically manifested kidney disease (186) suggests that not only the level of Gd-pIgA1 but also the antigenic determinants in the HR of Gd-IgA1, and the level and perhaps specificity of corresponding IgG autoantibodies that lead to marked differences in the serum levels of CIC and, most importantly, CIC molecular properties, especially with respect to the molecular mass, play important roles in disease expression (24). Here, IGHA1 is linked to kidney disorder.