Iron-refractory iron deficiency anemia

Two Novel TMPRSS6 Variants in a Compound Heterozygous Child With Iron Refractory Iron Deficiency Anemia

We describe a Caucasian family with asymptomatic, nonconsanguineous parents, and a daughter with unexplained microcytic anemia diagnosed on routine hemoglobin screening at her 12-month well child check. After failed response to oral and parental iron supplementation, iron refractory iron deficiency anemia was suspected. The family underwent genetic testing and the proband was found to be a compound heterozygote for 2 previously unreported TMPRSS6 variants.

New thiazolidinones reduce iron overload in mouse models of hereditary hemochromatosis and β-thalassemia

Genetic iron-overload disorders, mainly hereditary hemochromatosis and untransfused β-thalassemia, affect a large population worldwide. The primary etiology of iron overload in these diseases is insufficient production of hepcidin by the liver, leading to excessive intestinal iron absorption and iron efflux from macrophages. Hepcidin agonists would therefore be expected to ameliorate iron overload in hereditary hemochromatosis and β-thalassemia. In the current study, we screened our synthetic library of 210 thiazolidinone compounds and identified three thiazolidinone compounds, 93, 156 and 165, which stimulated hepatic hepcidin production. In a hemochromatosis mouse model with hemochromatosis deficiency, the three compounds prevented the development of iron overload and elicited iron redistribution from the liver to the spleen. Moreover, these compounds also greatly ameliorated iron overload and mitigated ineffective erythropoiesis in β-thalassemic mice. Compounds 93, 156 and 165 acted by promoting SMAD1/5/8 signaling through differentially repressing ERK1/2 phosphorylation and decreasing transmembrane protease serine 6 activity. Additionally, compounds 93, 156 and 165 targeted erythroid regulators to strengthen hepcidin expression. Therefore, our hepcidin agonists induced hepcidin expression synergistically through a direct action on hepatocytes via SMAD1/5/8 signaling and an indirect action via eythroid cells. By increasing hepcidin production, thiazolidinone compounds may provide a useful alternative for the treatment of iron-overload disorders.

Iron Refractory Iron Deficiency Anemia Due to 374 Base Pairs Deletion in the TMPRSS6 Gene

Iron refractory iron deficiency anemia is an autosomal recessive disorder arising from defects in iron metabolism that cause microcytic anemia to grow resistant to treatment. The patients usually do not respond to orally administered iron treatment and partially respond to intravenous iron administration. Mutations of TMPRSS6 gene which encodes matriptase-2 are the main cause of the disorder. Here, we describe the case of a 6-month-old Syrian boy who had hypochromic-microcytic anemia and normal ferritin levels at presentation. The patient did not respond to 1 month of iron therapy and his hemoglobin levels increased only after red blood cell transfusion. Mutation analysis demonstrated a novel 374 base pairs homozygote deletion spanning exon 15 of TMPRSS6 gene. Our results expand the mutation spectrum of TMPRSS6 gene in iron refractory iron deficiency anemia.

Intravenous Iron Sucrose for Treatment of Iron Deficiency Anemia in Pediatric Inflammatory Bowel Disease

OBJECTIVES

Iron deficiency anemia (IDA) is a common complication of pediatric inflammatory bowel disease (IBD), yet the effectiveness of oral iron supplementation is limited. Intravenous iron sucrose is an effective and safe alternative treatment for IDA in adults with IBD, but its role in the treatment of IDA in pediatric IBD is unclear. The primary aim of this study was to evaluate the use of iron sucrose in pediatric IBD subjects with IDA and determine the clinical response as measured by improvement in hemoglobin concentration. The secondary aim was to describe adverse events associated with iron sucrose use in this cohort.

METHODS

A retrospective chart review was performed of all pediatric patients with IBD receiving iron sucrose infusions for IDA at a single tertiary care center between 2011 and 2015.

RESULTS

Seventy-two subjects (53 with Crohn disease, 11 with ulcerative colitis, and 8 with IBD-unclassified) received a total of 273 iron sucrose infusions. Forty-three subjects qualified for the efficacy analysis. There was a significant increase in hemoglobin over the treatment course, with mean (±SD) hemoglobin increasing from 9.6 ± 1.2 g/dL at baseline to 12.1 ± 1.3 g/dL after iron sucrose treatment (P < 0.001). Eighteen adverse events were reported in 13 subjects (18.1% of subjects and 6.6% of infusions). No anaphylaxis reactions occurred and none of the adverse events were, however, life-threatening or required hospitalization.

CONCLUSIONS

Intravenous iron sucrose is a safe and potentially efficacious treatment choice for IDA in pediatric IBD.

Iron Refractory Iron Deficiency Anemia in Dizygotic Twins Due to a Novel TMPRSS6 Gene Mutation in Addition to Polymorphisms Associated With High Susceptibility to Develop Ferropenic Anemia

Iron refractory iron deficiency anemia (IRIDA) is an autosomal recessive ferropenic anemia. Its hypochromic microcytic pattern is associated with low transferrin saturation, normal-high ferritin, and inappropriately high hepcidin level. This entity is caused by mutants of the TMPRSS6 gene that encodes the protein matriptase II, which influences hepcidin expression, an iron metabolism counterregulatory protein. We report two 29-year-old dizygotic female twins with ferropenic, hypochromic microcytic anemia with 20 years of evolution, refractory to oral iron therapy. After exclusion of gastrointestinal etiologies, IRIDA diagnosis was suspected and a novel mutation in the TMPRSS6 gene was identified. It was found in intron 11 (c.1396+4 A>T) and seems to affect the gene expression. In addition, 3 polymorphisms already associated with a higher risk of developing iron deficiency anemia were also found (D521D, V736A, and Y739Y). Our case reports an undescribed mutation causing IRIDA and supports the hypothesis that this clinical syndrome may be more common than previously thought and its genetics more heterogeneous than initially described.

A child with severe iron-deficiency anemia and a complex TMPRSS6 genotype

OBJECTIVES

We report a case of a 7-year-old girl with severe hypochromic microcytic anemia, who was unresponsive to classical iron supplements. We suspected IRIDA, iron-refractory iron-deficiency anemia, a genetic iron metabolism disorder, caused by TMPRSS6 variations. TMPRSS6 encodes matriptase-2, a negative regulator of hepcidin, and its pathological variants are related to normal to high levels of hepcidin. We analyzed the TMPRSS6 gene and we improved clinical management of the patient, selecting the appropriate supplementation therapy. Intervention & Technique: The parenteral iron therapy was started, but the patient was only partially responsive and the anemia persisted. To confirm the diagnosis, the TMPRSS6 gene sequence was analyzed by DNA sequencing and other relevant biochemical parameters were evaluated.

RESULTS

The TMPRSS6 sequence analysis showed a complex genotype with a rare heterozygous missense variant, in addition to other common polymorphisms. The serum hepcidin value was normal. We unexpectedly observed a normalization of patient's hemoglobin (Hb) levels only after liposomal iron treatment.

DISCUSSION AND CONCLUSION

The proband was symptomatic for IRIDA during a critical phase of growth and development, but we did not find a clearly causative genotype. A long-term result, improving stably patient's Hb levels, was obtained only after liposomal iron supplementation. Children may be at greater risk for iron deficiency and the degree of anemia as well as the response to the iron supplements varies markedly patient to patient. Here, we show the importance of comprehensive study of these patients in order to collect useful information about genotype-phenotype association of genes involved in iron metabolism.

Iron-refractory iron deficiency anemia (IRIDA) cases with 2 novel TMPRSS6 mutations

Iron-refractory iron deficiency anemia (IRIDA) is a rarely diagnosed autosomal recessive disorder that presents with hypochromic, microcytic anemia due to mutations in TMPRSS6, which encodes matriptase-2. Contrary to classical iron deficiency anemia, serum hepcidin levels are found to be elevated in this disorder. Here, we report 5 cases from 4 unrelated families with inadequate response to iron therapy, who were consequently diagnosed as IRIDA. The mean age of the cases at diagnosis was 5.0 years (range: 0.7-11.3 years). All cases were either homozygous or compound heterozygous for missense or frameshift mutations in the TMPRSS6 gene, 2 of the mutations being novel (Cys410Ser and Leu689Pro). IRIDA should be considered in patients with findings of iron deficiency anemia unresponsive to oral iron therapy, whose serum ferritin levels are found normal or elevated.