[Telomeropathies: A study of 15 cases]

INTRODUCTION

Telomeres are composed of a repeated sequence of double-stranded nucleotides TTAGGG and numerous proteins including the Shelterin complex. Their main role is to maintain the stability of the genome during cell replication through a mechanism of copying the repeted sequence by the telomerase complexe. All the diseases involving a deregulation of this complex are now grouped together under the term telomeropathies. They are difficult to diagnose and manage. Our objective was to describe the clinico-biological characteristics and treatments used, in patients affected by telomeropathies previously seen by an hematologist followed at the Lille University Hospital Center.

METHODS

This is a retrospective, single-center study carried out within the department of internal medicine-clinical immunology, Reference center for rare autoimmune and systemic diseases at Lille University Hospital Center between 2005 and 2020 including all patients followed for telomeropathy.

RESULTS

Probands and relatives were included. Fifteen patients were studied from 10 independant families. Sixty percent had an heterozygous TERC gene mutation. Sixty seven percent had haematological diseases including macrocytosis, anemia and/or thrombocytopenia, 20 % had a fibrotic hepatic disease, 27 % had a fibrotic pulmonary disease. Lymphocyte immunophenotyping showed a double negative T lymphocyte population with γδ TCR expression in 5 (33 %) patients. Forty-seven percent of the patients had not received any treatment. Twenty-seven percent were on androgen therapy. Twenty percent had received cyclosporine and 13 % anti-lymphocyte serum in the context of initial misdiagnosis.

CONCLUSION

It is important to be aware of the complexity of telomeropathies, a differential diagnosis of immune aplastic anemia, in order to optimize management and avoid inappropriate treatments. Allografting of hematopoietic stem cells is the only potentially curative treatment. Our analysis found particularities in immunophenotyping lymphocyte not previously described to our knowledge, whose physiopathological imputability remains to be demonstrated.

[Paroxysmal nocturnal hemoglobinuria: An unknown cause of thrombosis?]

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired disorder of hematopoietic stem cells. Somatic mutation in the phosphatidylinositol glycan class A (PIG-A), X-linked gene, is responsible for a deficiency in glycosphosphatidylinositol-anchored proteins (GPI-AP). The lack of one of the GPI-AP complement regulatory proteins (CD55, CD59) leads to hemolysis. The disease is diagnosed with hemolytic anemia, marrow failure and thrombosis. Thromboembolic complication occurs in 30% of patient after 10 years of follow-up and is the first event in one out of 10 patients. The two most common sites are hepatic and cerebral veins. These locations are correlated with high risk of death. Currently, these data are balanced with the use of a monoclonal antibody (Eculizumab), which has significantly improved the prognosis with a survival similar to general population after 36 months of follow-up. Anticoagulant treatment is recommended after a thromboembolic event but has no place in primary prophylaxis.