Two novel variants of the ABCG5 gene cause xanthelasmas and macrothrombocytopenia: a brief review of hematologic abnormalities of sitosterolemia.

Essentials Diagnosis of sitosterolemia, a rare recessive or syndromic disorder, is usually delayed. Peripheral blood smear is extremely useful for establishing the suspicion of sitosterolemia. High-throughput sequencing technology enables the molecular diagnosis of inherited thrombocytopenias. Accurate characterization of sitosterolemia helps us determine appropriate management. SUMMARY: Background Sitosterolemia (STSL) is a recessive inherited disorder caused by pathogenic variants in the ABCG5 and ABCG8 genes. Increased levels of plasma plant sterols (PSs) usually result in xanthomas and premature coronary atherosclerosis, although hematologic abnormalities may occasionally be present. This clinical picture is unfamiliar to many physicians, and patients may be at high risk of misdiagnosis. Objectives To report two novel ABCG5 variants causing STSL in a Spanish patient, and review the clinical and mutational landscape of STSL. Patient/Methods A 46-year-old female was referred to us with lifelong macrothrombocytopenia. She showed familial hypercholesterolemia-related xanthomas. Molecular analysis was performed with high-throughput sequencing. Plasma PS levels were evaluated with gas-liquid chromatography. The STSL landscape was reviewed with respect to specific online databases and all reports published since 1974. Results A blood smear revealed giant platelets and stomatocytes. Novel compound heterozygous variants were detected in exons 7 (c.914C>G) and 13 (c.1890delT) of ABCG5. The patient showed an increased plasma level of sitosterol. These findings support the diagnosis of STSL. In our review, we identified only 25 unrelated STLS patients who presented with hematologic abnormalities including macrothrombocytopenia. It remains unknown why only some patients develop hematologic abnormalities. Conclusions This is the first Spanish STSL patient to be reported and molecularly characterized. The early diagnosis of STLS is strongly supported by the presence of stomatocytes in blood smears. The definitive diagnosis of STSL by measurement of serum PS levels and molecular analyses prompted the use of ezetimibe therapy.

Design and application of a 23-gene panel by next-generation sequencing for inherited coagulation bleeding disorders.

INTRODUCTION: Molecular testing of Inherited bleeding coagulation disorders (IBCDs) not only offers confirmation of diagnosis but also aids in genetic counselling, prenatal diagnosis and in certain cases genotype-phenotype correlations are important for predicting the clinical course of the disease and to allow tailor-made follow-up of individuals. Until recently, genotyping has been mainly performed by Sanger sequencing, a technique known to be time consuming and expensive. Currently, next-generation sequencing (NGS) offers a new potential approach that enables the simultaneous investigation of multiple genes at manageable cost. AIM: The aim of this study was to design and to analyse the applicability of a 23-gene NGS panel in the molecular diagnosis of patients with IBCDs. METHODS: A custom target enrichment library was designed to capture 31 genes known to be associated with IBCDs. Probes were generated for 296 targets to cover 86.3 kb regions (all exons and flanking regions) of these genes. Twenty patients with an IBCDs phenotype were studied using NGS technology. RESULTS: In all patients, our NGS approach detected causative mutations. Twenty-one pathogenic variants were found; while most of them were missense (18), three deletions were also identified. Six novel mutations affecting F8, FGA, F11, F10 and VWF genes, and 15 previously reported variants were detected. NGS and Sanger sequencing were 100% concordant. CONCLUSION: Our results demonstrate that this approach could be an accurate, reproducible and reliable tool in the rapid genetic diagnosis of IBCDs.

Influence of donor age in allogeneic stem cell transplant outcome in acute myeloid leukemia and myelodisplastic syndrome.

The impact of donor age in patients with acute myeloid leukemia and myelodysplastic syndrome who underwent allogeneic hematopoietic stem cell transplant (HSCT) remains unclear. In the current study, we evaluate 179 consecutive patients who received an HSCT, from January 2000 to January 2013, in our Institution. Most of the HSCT (91%) were HLA-matched. Patient and donor median age were 51 years (18-69) and 47 years (12-75) respectively, and 81 donors (45%) were older than 50 years. The median follow-up was 38 months (range 1-138), Kaplan-Meier estimated 3-year overall survival (OS) was 63% and disease free survival (DFS) was 56%. Interestingly, patients who received an HSCT from a donor older age (>50 y) showed a poorer OS (51% vs 73%; p=0.01), as well as a higher TRM (20% vs 8%; p=0.038) and higher relapse rate (28% vs 39%; p=0.03). In a stratified subanalysis, 3-year estimated OS was significantly lower among patients undergoing an HSCT from >50 years sibling donors compared to those receiving an HSCT from <50 years unrelated donor (54% vs 72%; p<0.001). In summary, we can conclude that receiving an HSCT from a donor over 50 years old is associated with poorer outcome in patients diagnosed with MDS and AML, and this information may be incorporated into the complex process of donor selection.

Linking divergent selection on vegetative traits to environmental variation and phenotypic diversification in the Iberian columbines (Aquilegia).

Divergent selection is a key in the ecological theory of adaptive radiation. Most evidence on its causes and consequences relies on studies of pairs of populations or closely related taxa. However, adaptive radiation involves multiple taxa adapted to different environmental factors. We propose an operational definition of divergent selection to explore the continuum between divergent and convergent selection in multiple populations and taxa, and its links with environmental variation and phenotypic and taxonomic differentiation. We apply this approach to explore phenotypic differentiation of vegetative traits between 15 populations of four taxa of Iberian columbines (Gen. Aquilegia). Differences in soil rockiness impose divergent selection on inflorescence height and the number of flowers per inflorescence, likely affecting the processes of phenotypic and, in the case of inflorescence height, taxonomic diversification between taxa. Elevational variation imposes divergent selection on the number of leaves; however, the current pattern of divergent selection on this trait seems related to ecotypic differentiation within taxa but not to their taxonomic diversification.