Chronic steroid-response pancytopenia and increased bone density due to thromboxane synthase deficiency

Middle-aged women with hematodiaphyseal dysplasia: Ghosal syndrome: Case report

Ghosal hematodiaphyseal dysplasia (GHDD) is a rare autosomal recessive disorder characterized by increased bone density involving diaphyses of long bones and defective hematopoiesis. It is due to biallelic variants in the TBXAS1 (OMIM*274180) gene, which encodes for thromboxane synthase. We present a rare case of a middle-aged woman who presented with chronic anemia and bone pain. About 31-year-old Southeast Asian female with a history of persistent iron deficiency anemia (6.1 gm/dL) presents with bilateral knee pain for 4 years. Autoimmune panel turned out to be negative. CT scan of the lower limbs showed multilamellated endosteal thickening specifically involving diaphyses with severe narrowing of medullary canal. PET CT scan revealed tubular remodeling, intramedullary ground glass matrix, and mild cortical thickening with increased FDG uptake in diaphyseal regions of femur and tibia. Bone marrow biopsy of left tibia revealed fibrocellular marrow with dyserythropoiesis. Considering the slow progression of illness over 4 years and radiological evidence suggestive of bone remodeling with severe narrowing of medullary canal as the cause of anemia, the patient underwent molecular analysis for GHDD. Results revealed homozygous p.Arg412Gln (exon 11) in TBXAS1 gene. Considering the effect of NSAIDs on cyclooxygenase and its downstream metabolites, oral Aspirin 150 mg/day was initiated. Hemoglobin improved to 11 gm/dL at 3-month follow-up visit. The complexity of reaching a diagnosis of GHDD underscores the importance of maintaining a high clinical suspicion and thorough analysis of radiological evidence. The treatment for GHDD involves aspirin, a readily available drug.

Steroid-responsive anemia with bony dysplasias: What lurks behind!

Ghosal hematodiaphyseal dysplasia (GHDD) is an autosomal recessive disorder characterized by diaphyseal dysplasia of long bones, bone marrow fibrosis, and steroid-responsive anemia. Patients with this disease have a mutation in the thromboxane-AS1 (TBXAS1) gene located on chromosome 7q33.34. They present with short stature, varying grades of myelofibrosis, and, hence cytopenias. Patients with the above presentation were evaluated through clinical presentation, X-ray of long bones, bone marrow examinations, and confirmed by genetic testing. In this article, we present two cases: The first case is a 3-year-old boy who presented with progressive pallor and ecchymotic patches for a year. On investigation, he had bicytopenia and bone marrow fibrosis. His anemia was steroid responsive and was finally diagnosed as GHDD. The second case is a 20-month-old girl who presented with blood in stools, developmental delay, anemia, and increased intensity of long bones on X-ray. Since other investigations were normal, suspicion of GHDD was raised, and a genetic workup was conducted which suggested mutation in TBXAS1 gene, confirming the diagnosis of GHDD. Children with refractory anemia and cortical thickening on skeletogram should always be evaluated for dysplasias. Timely treatment with steroids reduces transfusion requirements and halts bone damage, thus leading to better growth and improved quality of life.

Nonsteroidal anti-inflammatory drugs as a targeted therapy for bone marrow failure in Ghosal hematodiaphyseal dysplasia

Advances in genomic diagnostics hold promise for improved care of rare hematologic diseases. Here, we describe a novel targeted therapeutic approach for Ghosal hematodiaphyseal dysplasia, an autosomal recessive disease characterized by severe normocytic anemia and bone abnormalities due to loss-of-function mutations in thromboxane A synthase 1 (TBXAS1). TBXAS1 metabolizes prostaglandin H2 (PGH2), a cyclooxygenase (COX) product of arachidonic acid, into thromboxane A2. Loss-of-function mutations in TBXAS result in an increase in PGH2 availability for other PG synthases. The current treatment for Ghosal hematodiaphyseal dysplasia syndrome consists of corticosteroids. We hypothesize that nonsteroidal anti-inflammatory drugs (NSAIDs), which inhibit COX-1 and COX-2, could ameliorate the effects of TBXAS1 loss and improve hematologic function by reducing prostaglandin formation. We treated 2 patients with Ghosal hematodiaphyseal dysplasia syndrome, an adult and a child, with standard doses of NSAIDs (aspirin or ibuprofen). Both patients had rapid improvements concerning hematologic parameters and inflammatory markers without adverse events. Mass spectrometry analysis demonstrated that urinary PG metabolites were increased along with proinflammatory lipoxygenase (LOX) products 5-hydroxyeicosatetraenoic acid and leukotriene E4. Our data show that NSAIDs at standard doses surprisingly reduced both COX and LOX products, leading to the resolution of cytopenia, and should be considered for first-line treatment for Ghosal hematodiaphyseal dysplasia syndrome.

Novel TBXAS1 variants in two Indian children with Ghosal hematodiaphyseal dysplasia: A concise report

Ghosal hematodiaphyseal dysplasia (GHDD) is a rare, autosomal recessive condition characterised by diaphyseal dysplasia of long bones with defective haematopoiesis. We describe 2 such cases with clinical and radiological evidence of GHDD. Molecular analysis revealed novel variants in TBXAS1 gene in both of them. Suspicion and confirmation of this entity is crucial in cases of refractory anemia with bony deformities, as the clinical manifestations in this entity are usually well responsive to corticosteroids.

Novel compound heterozygous variants of TBXAS1 presenting with Ghosal hematodiaphyseal dysplasia treated with steroids

BACKGROUND

Homozygous or compound heterozygous pathogenic variants in the thromboxane A synthase 1 (TBXAS1) gene are associated with Ghosal hematodiaphyseal dysplasia (GHDD) which is characterized by defective hematopoiesis and increased bone density of long bones.

METHODS

Patients 1 and 2 are identical twins, who presented with red blood cell transfusion-dependent normocytic anemia and thrombocytopenia with bone marrow fibrosis and cortical bone thickening of long bones on plain radiograph. To clarify the etiology of their anemia and thrombocytopenia, whole blood was used for the DNA extraction and analyzed using next-generation sequencing (NGS) on an in-house bone marrow failure syndrome panel.

RESULTS

The NGS results indicated that these two patients carried two heterozygous variants in TBXAS1, exon7, c.583_584del, p.Ala195Leufs*12, and exon12, c.1420G>T, p.Gly474Trp, which were inherited from their mother and father, respectively. Patients 1 and 2 have been on chronic oral steroids with normalization of hemoglobin and platelet count after steroid initiation. Patient 3 is their sister who has normal blood counts but also has the same variants in TBXAS1 as her brothers. Radiographs showed cortical bone thickening and she has not required any treatment or transfusion.

CONCLUSION

We report three Caucasian siblings from non-consanguineous parents with novel compound heterozygous variants of TBXAS1 presenting with the phenotypes of GHDD. These three cases illustrate the variable clinical expressivity of the GHDD from two-compound heterozygous pathogenic variants of TBXAS1.

Bone fragility in patients affected by congenital diseases non skeletal in origin

BACKGROUND

Bone tissue represents a large systemic compartment of the human body, with an active metabolism, that controls mineral deposition and removal, and where several factors may play a role. For these reasons, several non-skeletal diseases may influence bone metabolism. It is of a crucial importance to classify these disorders in order to facilitate diagnosis and clinical management. This article reports a taxonomic classification of non-skeletal rare congenital disorders, which have an impact on bone metabolism METHODS: The International Osteoporosis Foundation (IOF) Skeletal Rare Diseases Working Group (SRD-WG), comprised of basic and clinical scientists, has decided to review the taxonomy of non-skeletal rare disorders that may alter bone physiology.

RESULTS

The taxonomy of non-skeletal rare congenital disorders which impact bone comprises a total of 6 groups of disorders that may influence the activity of bone cells or the characteristics of bone matrix.

CONCLUSIONS

This paper provides the first comprehensive taxonomy of non-skeletal rare congenital disorders with impact on bone physiology.