Francesca Clementina Radio

A novel missense mutation in SLC40A1 results in resistance to hepcidin and confirms the existence of two ferroportin-associated iron overload diseases

Ferroportin‐related iron overload disease differs from haemochromatosis in that it has a dominant mode of inheritance and is usually associated with macrophage iron sequestration. However, it is thought that mutations with opposite effects on protein functions, i.e. loss‐of‐function versus gain‐of‐function mutations, are responsible for variable phenotype presentations. The present study investigated the functional relevance of a novel ferroportin variant: the c.1502 A>G transition, which changes amino acid 501 from tyrosine to cysteine (p.Y501C). This novel variant was identified in a pedigree originating from Central Italy and, although an intra‐familial phenotype heterogeneity was observed, it co‐segregated with an iron overload picture similar to that of the HFE‐related typical haemochromatosis. In cultured cells, the p.Y501C mutant protein reached the plasma membrane and retained a full iron export ability. By contrast, it was resistant to inhibition by hepcidin. These findings confirm that certain ferroportin mutations compromise the activity of hepcidin in iron homeostasis, mimicking hepcidin deficiency as described in all types of hemochromatosis.

Association of hepcidin promoter c.-582 A>G variant and iron overload in thalassemia major

The liver peptide hepcidin is the key regulator of iron homeostasis. This report shows that liver iron content and serum ferritin levels are greater in thalassemia patients with the −582G polymorphic change in the hepcidin promoter as compared with patients with the wild-type (A) sequence. This observation suggests that this change might influence the iron status of irregularly chelated thalassemic patients. See related perspective article on page 1185. Hepcidin is a 25-amino acid peptide, derived from cleavage of an 84 amino acid pro-peptide produced predominantly by hepatocytes. This molecule, encoded by the hepcidin antimicrobial peptide (HAMP) gene shows structural and functional properties consistent with a role in innate immunity. Moreover, as demonstrated in mice and humans, hepcidin is a major regulator of iron metabolism, and acts by binding to ferroportin and controlling its concentration and trafficking. In this study we investigated the influence that mutations in HAMP and/or hemocromatosis (HFE) genes might exert on iron metabolism in a group of poly-transfused thalassemic patients in preparation for bone marrow transplantation. Our results showed that the presence of the c.-582 A>G polymorphism (rs10421768) placed in HAMP promoter (HAMP-P) might play a role in iron metabolism, perhaps varying the transcriptional activation that occurs through E-boxes located within the promoter.

TFR2-related hereditary hemochromatosis as a frequent cause of primary iron overload in patients from Central-Southern Italy

OBJECTIVE Hereditary hemochromatosis (HH) is a common Mendelian disorder of iron metabolism. Eighty percent of northern Europeans descendant HH patients carry the same mutation (p.C282Y) in the HFE gene. Simultaneously, due to a founder effect, its frequency varies considerably between different populations. In Central-Southern Italy the prevalence of p.C282Y mutation is low and in several patients the disease has different causes. Four additional rarer forms have been described. Type 3 HH has been reported in about 50 families and no more than 30 TFR2 pathogenic mutations have been globally identified. The aim of this study is to assess the TFR2 role in non-HFE HH pathogenesis. STUDY DESIGN AND SETTING TFR2 sequence analysis was performed on 45 Italian patients without HFE mutations. RESULTS This study revealed TFR2 biallelic pathogenic mutations in 7/45 (15.6%) individuals. Moreover monoallelic TFR2 deleterious defects (18%) or polymorphisms with unclear meaning (36%) were identified. Besides, we recognized 10 novel variants and 9 described changes. CONCLUSION We believe this to be the largest series of type 3 HH patients described so far. Present findings support the hypothesis of a main role of the TFR2 gene in HH pathogenesis in those regions, such as Central-Southern Italy, where the p.C282Y frequency is low.

Hereditary hemochromatosis type 1 phenotype modifiers in Italian patients. The controversial role of variants in HAMP, BMP2, FTL and SLC40A1 genes.

Hereditary hemochromatosis (HH) is a heterogeneous disorder of iron metabolism. The most common form of the disease is Classic or type 1 HH, mainly caused by a biallelic missense p.Cys282Tyr (c.845G>A) mutation in the HFE gene. However, the penetrance of p.Cys282Tyr/p.Cys282Tyr genotype is incomplete in terms of both biochemical and clinical expressivity. Lack of penetrance is thought to be caused by several genetic and environmental factors. Recently, a lot of evidences on HH genetic modifiers were produced, often without conclusive results. We investigated 6 polymorphisms (rs10421768 in HAMP gene, rs235756 in BMP2 gene, rs2230267 in FTL gene, rs1439816 in SLC40A1 gene, rs41295942 in TFR2 gene and rs2111833 in TMPRSS6 gene) with uncertain function in order to further evaluate their role in an independent cohort of 109 HH type 1 patients. Our results make it likely the role of rs10421768, rs235756, rs2230267 and rs1439816 polymorphisms, respectively in HAMP, BMP2, FTL and SLC40A1 genes in HH expressivity. In addition, previous and our findings support a hypothetical multifactorial model of HH, characterized by a principal gene (HFE in HH type 1) and minor genetic and environmental factors that still have to be fully elucidated.

Natural history of TFR2-related hereditary hemochromatosis in a 47-yr-old Italian patient

To the Editor: Hereditary haemochromatosis (HH) refers to a heterogeneous group of disorders characterized by increased iron absorption and augmented release from the reticuloendothelial system (1). In North Europe, more than 80% HH cases harbor mutations in the HFE gene (HH type I or classic HH), while a growing number of patients have been found carrying mutations in rarer genes, including HJV (HH type IIA), HAMP (HH type IIB), TFR2 (HH type III) and SLC40A1 (HH type IV) (2). Among them, mutations in TFR2 are reported in 21 apparently unrelated cases only, 14 of whom of Italian origin (3–6). Based on the very limited available data, HH type III is considered a milder disorder than HH type II (or juvenile HH), although it is usually more severe than HH type I (7). Here, we report a 47-yr-old Italian patient born to non-consanguineous parents. The proband, who is now 51 yr of age, began to complain of fatigue, erectile dysfunction, somnolence and frequent headaches at 31 yr of age. Two years later, insulin-dependent diabetes mellitus and hypogonadotropic hypogonadism were diagnosed. Shortly after, blood tests revealed high levels of liver enzymes. At 35 yr of age, the patient started to suffer from generalized arthralgia, which initially involved left shoulder, hands, feet and right knee and subsequently progressed, mainly affecting metacarpo-phalengeal joints and causing severe pain, deformation of hands and functional impairment in multiple sites. At age 37, radiographic evaluation showed characteristic degenerative changes (Fig. 1). At the age of 47 yr, the patient was evaluated by an endocrinologist, who found transferrin saturation (TS) 97% and ferritin 2982 ng ⁄mL, suggestive of HH. After that, the patient was referred to our dedicated outpatient service. Abdominal ultrasound revealed hepatomegaly. As the patient denied liver biopsy, he was investigated by magnetic resonance imaging, that revealed severe hepatic iron overload with a hepatic iron content >300 lmol ⁄g, according to Gandon et al. (8). Main biochemical data of the patient are summarized in Table 1. The patient was treated by phlebotomy for 1 yr with success (the estimated quantity of iron removed was about 18 g). Liver enzymes levels normalized and hepatomegaly recovered. Despite the achievement of subnormal serum ferritin levels, arthropathy continued to progress and left hip prosthesis replacement was requested at 50 yr of age. After obtaining informed consent, genomic DNA was extracted from peripheral blood leukocytes. In the patient, analysis of 17 HH-associated mutations was first performed as previously described (9) and identified the common heterozygous stop mutation p.E60X. Then, TFR2 (Genbank no. NC_000007.12) was directly A

Type 3 hereditary hemochromatosis in a patient from sub-Saharan Africa: Is there a link between African iron overload and TFR2 dysfunction?

Hereditary hemochromatosis (HHC) is a common genetic trait that increases the risk of developing systemic iron overload. The disorder is caused bymutations in genes coding various proteins involved in the regulation of iron access into the blood. In HHC, excessive iron storage may result in progressivemultiorgandamage,which can be treatedwith phlebotomy. HHC iswell defined inNorthern Europe. In this population,most affected individuals share the HFE recessive p.C282Y mutation, which is the most common genetic cause for classic (type 1) HHC [1]. It is presumed that p.C282Y appeared for the first time in the Celtic or Viking populationmore than 2000 years ago and followed their migrations. Accordingly, p.C282Y is less frequent in Southern Europeans, Native Americans, American of African descent, Pacific Islanders, and Asians, and nearly absent in Southern Africans [2]. Mutations in 4 additional genes (namely HJV, HAMP, TFR2 and SLC40A1) account for different, rarer forms of HHC (type 2A, type 2B, type 3, type 4), and can be found also in patients outside Northern Europe. Nevertheless, taken together, the 5 HHC-related genes do not explain the entire spectrum of iron overload in humans, especially in Southern Europe and in non-Caucasians [1,3]. In fact, iron overload is a complex phenotype resulting from the contribution of a wide range of factors, genetic and environmental, that can operate synergistically in the same individual. Accordingly, in sub-Saharan Africa, where iron overload has the highest prevalence, it is thought to be exacerbated by chronic excessive intake of dietary iron (African iron overload; AIO). AIO is a condition characterized by hepatic and probably, systemic iron overload, and is particularly common in rural areas. It is a frequent cause of cirrhosis and hepatocellular carcinoma and confers susceptibility to tuberculosis and other infections. Whether a genetic factor contributes or not to AIO is still a matter of debate [4,5]. We report a sub-Saharan African man with severe HHC carrying two novel TFR2mutations. To the best of our knowledge, this is the first case of molecularly characterized HHC in sub-Saharan Africans. The patient was a 49-year-old African originating from Burundi and referring to us for biochemical evidence of severe iron overload. He denied alcohol consumption and had normal dietary habits. At 46 years of age, the patient was hospitalized for malaria infection. Due to persistence of chronic fatigue and hypersomnia, he underwent further examinations revealing liver enlargement and steatosis at ultrasound, hyperferritinemia (3.516 μg/L), highly increased transferrin saturation (>100%) and microcytemia without other hematologic disorders. Liver cytonecrosis indexes were slightly increased (Table 1). Viral hepatitis was excluded by serum testing and a diagnosis of HHC was made on clinical grounds. In order to confirm the diagnosis, liver biopsy was proposed and, than, refused by the patient. Liver iron accumulation was measured by the superconducting quantum interference device (SQUID) method, underlining severe hepatic overload (estimated hepatic iron concentration: 16.8 mg/g dry weight; normal values≤3 mg/g). Measurement of liver

The "old theme" of variability versus transitory phenotypes in thanatophoric dysplasia type 1: two 19-week-old fetuses with ("San Diego" variant) and without ragged metaphyses due to the same FGFR3 mutation.

Conflict of interest: none. Correspondence to: Marco Castori, M.D., Ph.D., Division of Medical Genetics, Department of Molecular Medicine, Sapienza University, San Camillo-Forlanini Hospital, Circonvallazione Gianicolense 87, Rome 00152, Italy. E-mail: mcastori@scamilloforlanini.rm.it Article first published online in Wiley Online Library (wileyonlinelibrary.com): 16 August 2013 DOI 10.1002/ajmg.a.36131 TO THE EDITOR:

Hyperferritinemia-cataract syndrome: Long-term ophthalmic observations in an Italian family.

ABSTRACT Background: Hyperferritinemia-cataract syndrome (HCS) is a rare Mendelian condition characterized by bilateral cataract and high levels of serum ferritin in the absence of iron overload. Methods: HCS was diagnosed in three adult siblings. In two of them it was possible to assess lens changes initially in 1995 and again in 2013. Serum ferritin, iron, transferrin concentrations and transferrin saturation percentage were also measured, and the Iron Responsive Element (IRE) region of the L-ferritin gene (FTL) was studied. Results: Serum ferritin concentrations were considerably elevated while serum iron, transferrin and transferrin saturation levels were within the normal range in each sibling. Cataract changes in our patients were consistent with those previously reported in the literature. Progression of the cataract, an aspect of few studies in this syndrome, appeared to be quite limited in extent. The heterozygous +32G to T (-168G>T) substitution in the IRE of the FTL gene was detected in this family. Conclusions: Ophthalmic and biochemical studies together with genetic testing confirmed HCS in three family members. Although the disorder has been extensively described in recent years, little is known regarding cataract evolution over time. In our cases, lens evaluations encompassed many years, identified bilateral cataract of typical morphology and supported the hypothesis that this unique clinical feature of the disease tends to be slowly progressive in nature, at least in adults.

Expanding the clinical and molecular spectrum of PRMT7 mutations: 3 additional patients and review

Protein arginine methyltransferase 7 (PRMT7) is a member of a family of enzymes that catalyze the transfer of methyl groups from S‐adenosyl‐l‐methionine to nitrogen atoms on arginine residues. Arginine methylation is involved in multiple biological processes, such as signal transduction, mRNA splicing, transcriptional control, DNA repair, and protein translocation. Currently, 7 patients have been described harboring compound heterozygous or homozygous variants in the PRMT7 gene, causing a novel intellectual disability syndrome, known as SBIDDS syndrome (Short Stature, Brachydactyly, Intellectual Developmental Disability, and Seizures).

A novel germline mutation in CDK4 codon 24 associated to familial melanoma: Letter to the Editor

FIGURE 1 A, Family pedigree: segregation of CDK4 p.Arg24Leu mutation (*). B, CDK4 c.71G>T,p.Arg24Leu mutation. C, Homology model of the wild-type CDK4 (orange) in complex with p16(INK4)a (green). The CDK4 Arg24 residue (spheres) engages intermolecular interactions with the binding surface of the inhibitors. (D) to (G) Arg24 (orange) establishes salt bridges with 2 conserved aspartate residues of (D) p16(INK4)a, (E) p15(INK4)b, (F) p18(INK4)c and (G) p19(INK4)d (green). These interactions are lost in the mutant complexes (white). H, Predicted Gibbs free energy of binding variations (ΔΔG, in kcal/mol) between CDK4 and its partners upon mutations. ΔΔG values indicate decrease affinity Received: 29 June 2017 Revised: 21 August 2017 Accepted: 23 August 2017