First reported case of congenital thrombotic thrombocytopenic purpura in Taiwan with novel mutation of ADAMTS13 gene

Congenital thrombotic thrombocytopenic purpura (cTTP) is a rare disease that is defined as biallelic mutations of ADAMTS13 causing persistent absence of ADAMTS13 activity. The confirmed diagnosis requires a genetic study, and cTTP has never been previously reported in Taiwan. Our patient was a 29-year-old Taiwanese woman who presented with severe hyperbilirubinemia at birth. She had severe thrombocytopenia and hemolytic anemia at the age of 1, and another acute TTP event at the age of 7 triggered by an upper airway infection. Regular plasma replacement was started at age 12 based on a presumptive diagnosis of cTTP. Clinical diagnosis of cTTP, with undetectable ADAMTS13 activity and absence of ADAMTS13 inhibitor, was confirmed at age 27. A genetic study showed a previously reported mutation c.1921G to A, inherited from her father, and a maternally inherited, novel mutation at exon 12, c.1435+1dupG, which results in a splicing site change and frame shift. Reports of cTTP from East Asia, except Japan, are scarce. Some prevalent ADAMTS13 mutations are also race or region specific. With this report, we hope to raise awareness among physicians in Taiwan, promote early, proper diagnosis of cTTP, and reveal the true prevalence of cTTP in the Taiwanese population.

Thrombotic thrombocytopenic purpura developed during the conservative treatment of anti-phospholipase A2 receptor antibody-positive idiopathic membranous nephropathy: a case report

Background

Idiopathic membranous nephropathy (MN) is one of the major glomerulonephritis that cause nephrotic syndrome. The phospholipase A₂ receptor (PLA₂R) has recently been identified as an endogenous antigen of idiopathic MN. Thrombotic thrombocytopenic purpura (TTP) is a disorder characterized by schistocytes, hemolytic anemia, thrombocytopenia, and organ dysfunction which occurs as a result of thrombi. Patients with acquired TTP have autoantibodies against a disintegrin and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13). These autoantibodies act as an inhibitor and cause ADAMTS13 deficiency. Idiopathic MN and acquired TTP are usually considered as independent autoimmune diseases. We experienced a patient who developed TTP during the conservative treatment of idiopathic MN, with the coexistence of ADAMTS13 inhibitor and anti-PLA₂R antibody.

Case presentation

A 73-year-old man presented with thrombocytopenia, hemolytic anemia, disturbance of consciousness, and acute kidney injury after 4-year course of biopsy-proven idiopathic MN. ADAMTS13 activity was undetectable and the ADAMTS13 inhibitor was identified. Additionally, he was positive for anti-PLA₂R antibody. The patient did not have any diseases that could cause secondary thrombotic microangiopathy, and he was diagnosed with acquired TTP. Steroid therapy and plasma exchange were initiated and the acquired TTP resolved. MN achieved remission 3 months after the anti-PLA₂R antibody disappeared.

Conclusions

This is the first reported case of acquired TTP developed during conservative treatment of idiopathic MN, with both ADAMTS13 inhibitor and anti-PLA₂R antibody positive at the onset of the TTP. The present case suggests that idiopathic MN might be associated with the development of some cases of acquired TTP.