LAUSR

Dear Editor, Thrombocytopenia and absent radii (TAR) syndrome is a congenital disorder encountered in 1:100,000, characterized by thrombocytopenia due to defective megakaryopoiesis, associated with aplasia of the thin forearm bones, and cardiac abnormalities. Inheritance is autosomal recessive, often resulting from compound heterozygous mutations in RBM8A gene, with rare cases of parent-to-child transmission [1–3]. While the management of prenatal and neonatal TAR syndrome is well documented in the literature, the pregnancy course and the optimal peripartum management of mothers with TAR syndrome are not as defined. There are less than ten reported pregnancies in patients with TAR syndrome in the literature (Table 1). We are writing to discuss a case detailing the hematologic evaluation and management of a primigravid woman with TAR syndrome. A 23-year-old Caucasian woman (G1P0) at 17-weeks gestation presented with spontaneous lower extremity bruising and thrombocytopenia. She had been diagnosed with TAR syndrome in infancy with past episodes of easy bruising, epistaxis, and menorrhagia since early childhood. Family history was negative for consanguinity or hematologic disorders. On exam, blood pressure was normal, she had an appropriately gravid abdomen, lower extremity petechiae, bilateral hip ecchymoses, partially contracted forearms after prior wrist surgeries, and absent radii. Laboratory values included WBC 19.3 × 10/L, hemoglobin 11.2 g/dL, platelet count 26 × 10/L (down from 50 × 10/ L just 6 weeks prior), and MCV 90 fL. Peripheral blood film exam showed neutrophilia, thrombocytopenia, and no schistocytes. Her liver function studies, prothrombin time, activated partial thromboplastin time, fibrinogen, lactate dehydrogenase, and urinalysis were all normal. Bone marrow biopsy was 80% cellular with severe megakaryocytic hypoplasia. No dysplastic changes or increased blasts were noted ruling out myelodysplasia or acute leukemia. Metaphase chromosomes were normal. Genetic testing demonstrated a homozygous mutation in the RBM8A gene consistent with her clinical diagnosis of TAR syndrome. Ultrasound of fetus revealed normal forearm bone structure. Maternal platelet count remained stable but below 50 × 10/L throughout pregnancy. No platelet response was observed following a brief course of corticosteroids. Prior to elective C-section, one unit of platelets was transfused for platelet goal of 50 × 10/L followed by two units postpartum to minimize perioperative bleeding. The newborn exhibited intrauterine growth retardation, but was otherwise healthy. At outpatient follow-up visit 3 months later, maternal platelet count returned to baseline (90 × 10/L). Thrombocytopenia occurs in 7–12% of pregnancies, with potential to complicate maternal and fetal health during and following pregnancy. The onset and degree of thrombocytopenia during pregnancy prioritizes the differential diagnosis, even in such rare cases of a preexisting congenital thrombocytopenia. Gestational thrombocytopenia, preeclampsia, and HELLP syndrome tend to occur later in gestation. Thrombotic microangiopathy, disseminated intravascular coagulation, and immune thrombocytopenia (ITP) may instead occur at any time [10]. A comprehensive clinical and laboratory evaluation of our patient with TAR syndrome did not reveal signs of any of these conditions. Absence of response to corticosteroids suggested that her worsening thrombocytopenia was not * Robert T. Diep [email protected]