Familial thrombocytopenia due to a complex structural variant resulting in a WAC-ANKRD26 fusion transcript

Advances in genome sequencing have resulted in the identification of the causes for numerous rare diseases. However, many cases remain unsolved with standard molecular analyses. We describe a family presenting with a phenotype resembling inherited thrombocytopenia 2 (THC2). THC2 is generally caused by single nucleotide variants that prevent silencing of ANKRD26 expression during hematopoietic differentiation. Short-read whole-exome and genome sequencing approaches were unable to identify a causal variant in this family. Using long-read whole-genome sequencing, a large complex structural variant involving a paired-duplication inversion was identified. Through functional studies, we show that this structural variant results in a pathogenic gain-of-function WAC-ANKRD26 fusion transcript. Our findings illustrate how complex structural variants that may be missed by conventional genome sequencing approaches can cause human disease

Proliferação de linfócitos e apoptose de células CD5+ de bovinos infectados pelo vírus da leucose enzoótica bovina

Avaliaram-se a proliferação de linfócitos e a apoptose de células CD5+ de bovinos naturalmente infectados pelo vírus da leucose enzoótica bovina. Para tal, 100 vacas da raça Holandesa, em lactação, foram triadas quanto ao sorodiagnóstico para a leucose enzoótica bovina e o perfil hematológico, e 15 foram escolhidos e distribuídos uniformemente entre os três grupos, a saber: animais negativos, animais positivos alinfocitóticos e animais positivos e que manifestaram linfocitose persistente (LP). Para a avaliação da proliferação de linfócitos, procedeu-se ao isolamento das células mononucleares por gradiente de centrifugação, em que 2x10(6) linfócitos por mL foram plaqueados por poço e analisados por citometria de fluxo utilizando-se o fluorocromo CFSE-DA. A apoptose do sangue periférico deu-se utilizando a anexina V-FITC, e para a identificação das células CD5+, utilizaram-se anticorpos monoclonais. Ocorreu menor proliferação de linfócitos nos animais infectados e que manifestavam LP, e menor apoptose de células CD5+ do sangue periférico. Pode-se sugerir que o desenvolvimento da LP, resultante do aumento de linfócitos B, deve-se à redução do processo apoptótico das células CD5+, principal população infectada, e que a maior proliferação linfocitária pode se restringir apenas ao estádio inicial do desenvolvimento da LP

TMEM14C is required for erythroid mitochondrial heme metabolism

The transport and intracellular trafficking of heme biosynthesis intermediates are crucial for hemoglobin production, which is a critical process in developing red cells. Here, we profiled gene expression in terminally differentiating murine fetal liverderived erythroid cells to identify regulators of heme metabolism. We determined that TMEM14C, an inner mitochondrial membrane protein that is enriched in vertebrate hematopoietic tissues, is essential for erythropoiesis and heme synthesis in vivo and in cultured erythroid cells. In mice, TMEM14C deficiency resulted in porphyrin accumulation in the fetal liver, erythroid maturation arrest, and embryonic lethality due to profound anemia. Protoporphyrin IX synthesis in TMEM14C-deficient erythroid cells was blocked, leading to an accumulation of porphyrin precursors. The heme synthesis defect in TMEM14C-deficient cells was ameliorated with a protoporphyrin IX analog, indicating that TMEM14C primarily functions in the terminal steps of the heme synthesis pathway. Together, our data demonstrate that TMEM14C facilitates the import of protoporphyrinogen IX into the mitochondrial matrix for heme synthesis and subsequent hemoglobin production. Furthermore, the identification of TMEM14C as a protoporphyrinogen IX importer provides a genetic tool for further exploring erythropoiesis and congenital anemias