TTP and pregnancy

Unfolding the pathophysiology of congenital thrombotic thrombocytopenic purpura in pregnancy: lessons from a cluster of familial cases

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP), a rare, potentially life-threatening thrombotic microangiopathy, manifests either as congenital TTP or acquired forms. It is caused by the absence or severe depletion of a disintegrin and metalloproteinase with thrombospondin motifs 13 (ADAMTS13) protease, leading to the accumulation of ultra large von Willebrand factor multimers as well as extensive platelet adhesion and clumping, which can ultimately cause severe secondary end-organ damage. Pregnancy can provoke or exacerbate TTP, leading to maternal and fetal complications.

OBJECTIVE

In this report, we focused on pregnancy outcomes in a recently recognized cohort of congenital TTP patients of Bedouin Arab descent in southern Israel who were all homozygous for a novel c.3772delA variant of the ADAMTS13 gene, leading to the clinical manifestations of TTP largely during pregnancy.

STUDY DESIGN

All patients presented in this study belong to 2 closely related families of Arab Bedouin descent and were found to be homozygous for a novel ADAMTS13-c.3772delA variant. The cohort consisted of 19 females; 16 of them had congenital TTP and had been pregnant and were thus included. Patient data were collected from electronic medical records.

RESULTS

Of note, 13 women from our cohort, who delivered 14 fetuses (owing to 1 twin pregnancy), were diagnosed with congenital TTP following complicated pregnancies, which included recurrent pregnancy loss, stillbirth, early onset preeclampsia (both mild and severe), hemolysis, elevated liver enzymes and low platelet count syndrome, intrauterine growth restriction with abnormal Doppler flow, preterm premature rupture of membranes, and a total perinatal mortality rate of 30.7% (4/13). An additional 3 women, who were diagnosed owing to complications outside of pregnancy and at older ages, experienced TTP during their pregnancies, which occurred before diagnosis. Subsequent pregnancies were treated with fresh frozen plasma leading to a 100% fetal survival rate in the pregnancies that reached fetal viability. All placentas had lesions consistent with maternal vascular underperfusion. However, the severity and frequency of these lesions were lower in the 8 placentas from pregnancies treated with fresh frozen plasma.

CONCLUSION

This case series details a distinctive cohort of congenital TTP patients, all homozygous for the same, novel ADAMTS13 variant, who presented with clinical complications during pregnancy and maternal vascular lesions of underperfusion in the placenta. Our findings imply that the variant identified in the ADAMTS13 gene in our cohort may have a specific functional impact on the placenta, and that treatment with fresh frozen plasma during pregnancy ameliorates the course of the disease, leading to a milder phenotype or a normal pregnancy in the majority of cases.

Autoimmune Thrombotic Thrombocytopenic Purpura: Two Rare Cases Associated with Juvenile Idiopathic Arthritis and Multiple Sclerosis

Secondary thrombotic microangiopathies are associated with several underlying conditions, with most of them being resolved after the treatment of background disease. Thrombotic thrombocytopenic purpura (TTP) is a rare microangiopathy presenting with anemia, thrombocytopenia, and neurological deficits, occurring most often in various autoimmune diseases due to inhibition of ADAMTS13 by autoantibodies, as well as in pregnant women with or without an autoimmune substrate. In this article, we report two newly diagnosed TTP cases, who have not been published so far. The first is a 27-year-old woman with a history of polyarticular rheumatoid factor negative juvenile idiopathic arthritis, who presented with thrombocytopenia, anemia, schistocytes on blood smear, headache, and active arthritis. Originally she was treated successfully with plasma exchange, intravenous prednisone, and vincristine, and a few months after the TTP episode, she was commenced on rituximab, resulting in remission of primary disease and no relapse of TTP. The second case refers to a 29-year-old pregnant woman complaining of dizziness and fatigue with microangiopathic hemolytic anemia. She was treated with plasma exchanges, intravenous prednisolone, and INN human normal immunoglobulin with full remission of the TTP episode. Six and half years later, she was diagnosed with multiple sclerosis and was commenced on interferon beta-1 alpha, with no recurrent episode of TTP. These cases broaden the spectrum of autoimmune disorders manifested or complicated clinically by TTP. Furthermore, biological agents such as rituximab appear to be an effective treatment option for refractory cases of TTP related to systemic rheumatic disease, indicating an alternative therapeutic solution in persistent cases of this disorder.