Albertine Donker

Chapter 4 142 Concerning the genotype-phenotype relationship, there is a tendency towards lower Hb, MCV and TSAT in patients with two nonsense mutations. 10 Much is unknown on the influence of high frequency TMPRSS6 variants, other still unrecognized genes and environmental factors in the phenotypic expression of the disease. Furthermore, diagnosing IRIDA is challenging because of the highly variable phenotype 4,5,10 and the unclear genotype –phenotype relation. The optimal oral and/or intravenous iron treatment regimen has not been established yet. In this paper we describe the characteristics of 21 IRIDA patients and relatives in the Netherlands, the relation between genotype and phenotype in terms of age of presentation, severity of anemia and response to iron supplementation. Our observations add to the understanding of the clinical and genetic heterogeneity of IRIDA. They moreover suggest the TSAT/hepcidin ratio as a promising tool in the diagnosis of IRIDA.