Gray platelet syndrome (GPS) is a rare recessive disorder caused by biallelic variants in NBEAL2 and characterized by bleeding symptoms, the absence of platelet α-granules, splenomegaly, and bone marrow (BM) fibrosis. Due to the rarity of GPS, it has been difficult to fully understand the pathogenic processes that lead to these clinical sequelae. To discern the spectrum of pathologic features, we performed a detailed clinical genotypic and phenotypic study of 47 patients with GPS and identified 32 new etiologic variants in NBEAL2. The GPS patient cohort exhibited known phenotypes, including macrothrombocytopenia, BM fibrosis, megakaryocyte emperipolesis of neutrophils, splenomegaly, and elevated serum vitamin B12 levels. Novel clinical phenotypes were also observed, including reduced leukocyte counts and increased presence of autoimmune disease and positive autoantibodies. There were widespread differences in the transcriptome and proteome of GPS platelets, neutrophils, monocytes, and CD4 lymphocytes. Proteins less abundant in these cells were enriched for constituents of granules, supporting a role for Nbeal2 in the function of these organelles across a wide range of blood cells. Proteomic analysis of GPS plasma showed increased levels of proteins associated with inflammation and immune response. One-quarter of plasma proteins increased in GPS are known to be synthesized outside of hematopoietic cells, predominantly in the liver. In summary, our data show that, in addition to the well-described platelet defects in GPS, there are immune defects. The abnormal immune cells may be the drivers of systemic abnormalities such as autoimmune disease.

In acute portal vein thrombosis (APVT) unrelated to cirrhosis, anticoagulant therapy is classically started with low molecular weight heparin or vitamin K antagonists. New direct-acting oral anticoagulants (DOACs) are used in the treatment of venous thrombosis outside the splanchnic vascular bed, but not in the latter. We report a young female with APVT occurring in a non-cirrhotic liver linked to heterozygosity of factor V-Leiden and prothrombin G20210A gene mutations. Rivaroxaban was started, with total recanalization of the left and partial recanalization of the right portal vein branches, without complications. New DOACs do not need daily subcutaneous injections nor routinely blood coagulation control tests, making its use attractive, eventually increasing patient's compliance. If proved to be safe and effective in the future studies, its use may be extended to PVT treatment. This case shows that rivaroxaban was safe, not only prevented the extension of thrombosis in the portal tract, but also resolved PVT, at least partially.

We report the analysis by single-stranded conformation polymorphism of the essential sequences of the factor VIII (FVIII) gene (total length about 14 kb) including the entire coding sequence, flanking intronic sequences and the putative regulatory sequences 5' to the gene, in twelve unselected haemophilia A patients of Portuguese origin. Direct sequencing of the fragments with an altered migration pattern led to the identification of the disease-producing mutations in five patients. Three of these mutations, namely a 1 bp insertion in a motif of eight consecutive A residues at codon 1439 (FVIIIPorto3); a C to T transition at codon 1966 (Arg→Stop), found in an inhibitor-positive patient (FVIIIMontijo); and a G to A transition at codon 479 (Gly→ Arg; FVIIIPorto1), have been reported in other ethnic groups. The two novel mutations are the substitution of AG by GG at the 3' end of intron 4 (FVIIILisboa1 destroying the invariant splice acceptor sequence, and a G to A transition at codon 1948 resulting in an aspartic acid substitution for glycine (FVIIIporot2).

Rare pathogenic variants in either the ITGA2B or ITGB3 genes have been linked to autosomal dominant macrothrombocytopenia associated with abnormal platelet production and function, deserving the designation of Glanzmann Thrombasthenia-Like Syndrome (GTLS) or ITGA2B/ITGB3-related thrombocytopenia. To describe a series of patients with familial macrothrombocytopenia and decreased expression of αIIbβ3 integrin due to defects in the ITGA2B or ITGB3 genes. We reviewed the clinical and laboratory records of 10 Portuguese families with GTLS (33 patients and 11 unaffected relatives), including the functional and genetic defects. Patients had absent to moderate bleeding, macrothrombocytopenia, low αIIbβ3 expression, impaired platelet aggregation/ATP release to physiological agonists and low expression of activation-induced binding sites on αIIbβ3 (PAC-1) and receptor-induced binding sites on its ligand (bound fibrinogen), upon stimulation with TRAP-6 and ADP. Evidence for constitutive αIIbβ3 activation, occurred in 2 out of 9 patients from 8 families studied, but also in 2 out of 12 healthy controls. We identified 7 missense variants: 3 in ITGA2B (5 families), and 4 in ITGB3 (5 families). Three variants (αIIb: p.Arg1026Trp and p.Arg1026Gln and β3: p.Asp749His) were previously reported. The remaining (αIIb: p.Gly1007Val and β3: p.Thr746Pro, p.His748Pro and p.Arg760Cys) are new, expanding the αIIbβ3 defects associated with GTLS. The integration of the clinical and laboratory data allowed the identification of two GTLS subgroups, with distinct disease severity. Previously reported ITGA2B and ITGB3 variants related to thrombocytopenia were clustered in a confined region of the membrane-proximal cytoplasmic domains, the inner membrane clasp. For the first time, variants are reported at the outer membrane clasp, at the transmembrane domain of αIIb, and at the membrane distal cytoplasmic domains of β3. This is the largest single-center series of inherited macrothrombocytopenia associated with αIIbβ3 variants published to date.

Background: Hermansky-Pudlak syndrome (HPS) is a rare inherited platelet disorder characterized by bleeding diathesis, oculocutaneous albinism (OCA) and a myriad of often-serious clinical complications. Methods: We established the clinical and laboratory phenotype and genotype of six unrelated pedigrees comprising ten patients with clinical suspicion of HPS; including platelet aggregation, flow cytometry, platelet dense granule content, electron microscopy and high-throughput sequencing (HTS). Results: The clinical presentation showed significant heterogeneity and no clear phenotype-genotype correlations. HTS revealed two known and three novel disease-causing variants. The Spanish patients carried a homozygous p.Pro685Leufs17* deletion (n = 2) in HPS4, or the novel p.Arg822* homozygous variant (n = 1) in HPS3. In the case of two Turkish sisters, a novel missense homozygous HPS4 variant (p.Leu91Pro) was found. In two Portuguese families, genetic studies confirmed a previously reported nonsense variant (p.Gln103*) in DTNBP1 in three patients and a novel duplication (p.Leu22Argfs*33) in HPS6 in two unrelated patients. Conclusions: Our findings expand the mutational spectrum of HPS, which may help in investigating phenotype-genotype relationships and assist genetic counselling for affected individuals. This approach is a proof of principle that HTS can be considered and used in the first-line diagnosis of patients with biological and clinical manifestations suggestive of HPS.