Hereditary autoimmune thrombocytopenic purpura: an immunologic and genetic study

Copy-number variations in adult patients with chronic immune thrombocytopenia

OBJECTIVES

Immune thrombocytopenia (ITP) is an autoimmune disease with heterogeneous background. FCGR2C mutations were defined in one third of the patients but genetic players have not been fully elucidated yet. Although childhood ITP present as benign, ITP in adulthood is chronic disease with treatment challenges. This study aimed to focus on adult ITP patients using a whole genome genotyping that is valuable approach to identify the responsible genomic regions for the disease.

METHODS

Herein 24 adult primary-refractory for ITP patients were evaluated using HumanCytoSNP12BeadChip,Illumina. Forty-six age and sex matched healthy individuals, and ptients awith nonhematological conditions were analyzed as controls. Identified CNV regions were verified by qRTPCR. T-cell receptor beta and delta (TCRB/TCRG) clonality were assessed by heteroduplex analysis in mosaic cases.

RESULTS

Several CNV losses and gains were defined (losses:2q,7q,17q,19p, and gains: 1q,2p,3q,4q,7q,10q,12p,13q,14q,15q,17p,20q,21p,22q,Xp). Mosaic changes of different sizes (0.2-17.77Mb) were identified in five patients and three of them showed clonality. CNV regions that were unique to ITP patients were identified for the first time and among these genes, those related to immune regulation, and cellular trafficking were noteworthy. Conclusion: Identified CNV regions harbor several candidate genes, the functions of which might shed light on the pathogenesis of chronic ITP.

Controversies in the diagnosis and management of childhood acute immune thrombocytopenic purpura

Acute immune thrombocytopenic purpura (ITP) occurs most commonly in young children who present with severe isolated thrombocytopenia and purpura. A marrow examination is not required unless glucocorticoids are used, lest treatment mask incipient acute lymphoblastic leukemia, but controversy exists here. The recommendations for evaluation and management remain controversial, since prospective controlled trials have not been done. There is some consensus based on experience and empiric data. Almost all children with acute ITP will recover completely without therapy. Although the various treatments may increase the platelet count, they do not influence the outcome of the illness, may increase cost, and cause significant side effects. Therefore, careful observation may be the best management option for the patient with ITP, in the absence of severe bleeding. The data available relevant to these issues are discussed.

Idiopathic autoimmune thrombocytopenia and neutropenia in siblings

Familial incidences of autoimmune disorders involving red cells, white cells and platelets are rare. Two cases of autoimmune neutropenia and thrombocytopenia occurring in two adult brothers are reported here. One patient showed prompt recovery of white cells with steroids but needed IV IgG+ splenectomy for durable platelet recovery. His brother required splenectomy for durable recovery of white cells and platelets as he showed transient recovery with steroids and IV IgG.

Chronic isolated macrothrombocytopenia with autosomal dominant transmission: a morphological and qualitative platelet disorder

We studied 47 subjects belonging to 13 unrelated families with a history of mild haemorrhagic diathesis and chronic thrombocytopenia. 36 patients presented some degree of thrombocytopenia: 7/36 (19%) had slight thrombocytopenia (100-150 x 10(9)/L); 26/36 (72%) had mild thrombocytopenia (50-100 x 10(9)/L) and 3/36 (8%) had severe thrombocytopenia (< 50 x 10(9)/L). No correlation was observed between platelet count and the degree of haemorrhagic diathesis, which was mild in the majority of patients. Transmission was autosomal dominant. Platelet anisocytosis, increased percentage of large platelets and absence of leukocyte inclusions were observed in 26/30 (87%) of the examined blood smears. The ultrastructural appearance of platelets was normal. Megakaryocytes appeared normal in number in 10/10 patients, but showed asynchronous nuclear-cytoplasm maturation and mainly nonlobulated nuclei. Platelet aggregation was studied in 26 patients and either increased or decreased curves were variably observed in response to different aggregating agents. Platelet-associated IgG (PAIgG) was increased in 18/31 (58%) patients, while serum autoantibodies against platelet glycoproteins Ib/IX or IIb/IIIa were demonstrable in only 1 case. An increased expression of platelet surface glycoproteins Ib and IIb/IIIa, as studied by murine monoclonal antibodies binding in 17 cases, was observed. Platelet survival performed by 111Inoxine-labelled autologous platelets was normal in the 3 studied patients. Congenital macrothrombocytopenia confirms to be a distinct clinical disorder for which the name of "chronic isolated hereditary macrothrombocytopenia" is proposed.

Canine idiopathic thrombocytopenic purpura

Canine idiopathic thrombocytopenic purpura (ITP) is a disease in which antibodies bound to the surface of platelets mediate premature platelet destruction by macrophages. ITP in dogs and chronic ITP in humans are analogous diseases. This article draws on information from the literature on ITP in dogs and in humans, and reviews the pathogenesis, diagnosis, and treatment of ITP in dogs.

Familial lupoid thrombocytopenia

Familial lupoid thrombocytopenia affecting three subjects in three generations is reported. All subjects had antinuclear antibodies with or without antibodies to single-stranded DNA, an increase in platelet-associated IgG, and a family member with an autoimmune disease. These findings implicate a genetic contribution. All subjects shared a common HLA haplotype.

Familial segregation of cervical ribs, Sprengel anomaly, preaxial polydactyly, anal atresia, and urethral obstruction: a new syndrome?

In a consanguineous Jewish family originating from Bombay, India, the propositus presented with anal atresia, micropenis, urethral obstruction with secondary prune belly, omphalocele, patent urachus, and cryptorchidism. The kidneys were dysplastic and he had the Potter phenotype with limb deformities. Additional findings included IUGR with microcephaly, congenital heart defects, spinal anomalies, and hypoplastic lungs. The mother and all three sisters had cervical ribs, and she and one sister had 11 pairs of thoracic ribs. The other two sisters had chronic immune thrombopenia. One of those had bilateral Sprengel deformity with homovertebral bones, club feet, and microcephaly and the other sister also had unilateral preaxial hexadactyly. Although familial segregation of cervical ribs and Sprengel deformity has been reported, the association of the findings in this family is unique and may represent a new syndrome. X-linked dominant transmission may explain the severe manifestations in the affected male, but other modes of inheritance may also apply.

Characterization of novel platelet and endothelial cell target antigens in a family with genetic susceptibility to autoimmunity

This report describes a French Canadian family whose members exhibit a high incidence of allo- and autoantibodies to antigens present on both platelets and endothelial cells. This is correlated with various HLA specificities known to be associated with autoimmunity, such as A1, B8, DR3, and, in some cases, with clinical disorders, including nephritis, hypertension, and thrombocytopenia. Immunoblot analysis using platelet and endothelial cell lysates showed serum antibodies to a 75 kDa endothelial cell surface polypeptide and to polypeptides with apparent mass of 115 kDa and 26 kDa found on both platelets and endothelial cells. This 115 kDa internal platelet protein was also found in a variety of other cell types, such as mononuclear cells, and increased following cell activation. Monoclonal antibody immunobilization assays were used to characterize the 26 kDa polypeptide; in three of the four patients tested, an antibody to leukocyte differentiation antigen CD9 was identified. The asymptomatic child of the propositus also exhibited an autoantibody against an 80 kDa platelet protein which was sensitive to thrombin digestion, suggesting that this polypeptide may be platelet glycoprotein V. In addition, P1A1 alloantibody was identified in one sister who had given birth to a severely thrombocytopenic boy and who herself had a severe vascular rejection to a cadaver kidney 2 years prior to this study. The propositus also developed hypertensive renal disease following a pregnancy and became dialysis dependent. Thus, members of this family have developed a variety of antibodies, particularly to platelet and endothelial cell antigens. Some subjects have remained asymptomatic in spite of having autoantibodies. However, others have been seriously ill, and their immune response to these antigens is believed to have played a role in the pathogenesis of their neonatal alloimmune thrombocytopenic purpura, hypertensive renal disease, renal graft rejection, and thrombocytopenia.

Familial hereditary thrombocytopenia and HLA

Three generations of a Jewish family with hereditary thrombocytopenia (HT) are described. The disease was manifested clinically by mild bleeding tendency since infancy. Circumcision, however, did not result in excessive bleeding. HLA study in this family indicated that the HT locus is not linked to HLA.

Familial thrombocytopenia associated with platelet autoantibodies and chromosome breakage

An extended family is described in which three members had thrombocytopenia. These affected members had chromosomal changes resembling those found in Fanconi's anaemia, though they lacked the development defects associated with that syndrome. One had bone-marrow hypoplasia and died of squamous cell carcinoma of the mouth at the age of 27. In addition, all three had platelet autoantibodies not found in any other family members tested. There was no linkage between the thrombocytopenia and HLA groups. The nature of the association of thrombocytopenia, platelet autoantibodies and chromosomal abnormalities in this family remains doubtful.

Genetic factors predisposing to autoimmune diseases. Autoimmune hemolytic anemia, chronic thrombocytopenic purpura, and systemic lupus erythematosus

Genetic factors predisposing to autoimmune diseases were investigated in 10 families having more than one affected member. Seventy relatives and 23 spouses from two large kindreds (one in whom the proband had autoimmune hemolytic anemia and the other immune thrombocytopenic purpura) were examined for immunologically mediated disorders, autoantibodies, immunoglobulin abnormalities, and HLA genotypes. Significant differences between relatives and spouses were found for immune diseases (21 percent versus 0 percent; p = 0.02), antinuclear antibody titer of 1:80 or more (18 percent versus 0 percent; p = 0.04), single-strand DNA antibodies (18 percent versus 0 percent; p = 0.04), high-titer antinuclear antibody or antibodies to single-strand DNA or both (33 percent versus 0 percent; p = 0.001), and the combined frequencies of immune diseases and serologic abnormalities (44 percent versus 4 percent; p = 0.0004). Similar frequencies were found in 41 relatives from eight families in whom the proband had SLE. Segregation analyses using these abnormalities as genetic traits were most compatible with a Mendelian dominant model. Impressive odds (100:1) against linkage to HLA were calculated.