Next-generation sequencing of hereditary hemochromatosis-related genes: Novel likely pathogenic variants found in the Portuguese population

Abstract

Hereditary hemochromatosis (HH) is an autosomal recessive disorder characterized by excessive iron absorption resulting in pathologically increased body iron stores. It is typically associated with common HFE gene mutation (p.Cys282Tyr and p.His63Asp). However, in Southern European populations up to one third of HH patients do not carry the risk genotypes. This study aimed to explore the use of next-generation sequencing (NGS) technology to analyse a panel of iron metabolism-related genes (HFE, TFR2, HJV, HAMP, SLC40A1, and FTL) in 87 non-classic HH Portuguese patients. A total of 1241 genetic alterations were detected corresponding to 53 different variants, 13 of which were not described in the available public databases. Among them, five were predicted to be potentially pathogenic: three novel mutations in TFR2 [two missense (p.Leu750Pro and p.Ala777Val) and one intronic splicing mutation (c.967-1G NC)], one missense mutation in HFE (p.Tyr230Cys), and one mutation in the 5′-UTR of HAMP gene (c. -25GN A). The results reported here illustrate the usefulness of NGS for targeted iron metabolism-related gene panels, as a likely cost-effective approach for molecular genetics diagnosis of non-classic HH patients. Simultaneously, it has contributed to the knowledge of the pathophysiology of those rare iron metabolism-related disorders.

Haemochromatosis: a clinical update for the practising physician

“…This is partly due to environmental factors, including physiological blood loss, as well as the interaction of other genetic factors . Novel research is exploiting next‐generation sequencing techniques to identify these disease modifying‐genes that may close the gap in knowledge about incomplete penetrance of the C282Y substitution. At present, a definitive test to determine whether a person with the homozygous C282Y substitution will develop clinical symptoms remains elusive.…”

Causes of iron overload in blood donors – a clinical study

“…Table (including references ) provides an overview of the non‐ HFE mutations found in the study population. For each mutation, changes in the nucleotide and amino acid sequence are listed.…”

“…Genotype-segregated baseline data for the study population at the time of clinical evaluation. Table 4 (including references [18][19][20][21][22][23][24][25][26]) provides an overview of the non-HFE mutations found in the study population. For each mutation, changes in the nucleotide and amino acid sequence are listed.…”

Novel mutations in the bone morphogenetic protein 6 gene in patients with iron overload and non-homozygous genotype for the HFE p.Cys282Tyr mutation

“…Juvenile hemochromatosis (JH) is type 2, subdivided into type 2A, related to a pathogenic variant in the HJV (hemojuvelin) gene, and type 2B, related to mutations in the HAMP (hepcidin) gene; type 3 is related to a pathogenic variant in the TFR2 gene; and type 4 is related to a pathogenic variant in the SLC40A1 (ferroportin) gene (9). Some studies have reported that sequencing the five main genes related to hemochromatosis may not be sufficient to explain all cases of primary iron overload (IO) (10,11). A Portuguese group, using next generation sequencing (NGS), evaluated a panel of genes involved in iron metabolism (HFE, TFR2, HJV, HAMP, SLC40A1 and FTL (L-ferritin)) in 87 patients with a non-classical form of hemochromatosis, and were unable, in some patients, to detect changes that could explain their phenotype, which suggests that the genetic changes possibly responsible for IO in these patients could be located in genes not addressed in this study (11).…”

“…Some studies have reported that sequencing the five main genes related to hemochromatosis may not be sufficient to explain all cases of primary iron overload (IO) (10,11). A Portuguese group, using next generation sequencing (NGS), evaluated a panel of genes involved in iron metabolism (HFE, TFR2, HJV, HAMP, SLC40A1 and FTL (L-ferritin)) in 87 patients with a non-classical form of hemochromatosis, and were unable, in some patients, to detect changes that could explain their phenotype, which suggests that the genetic changes possibly responsible for IO in these patients could be located in genes not addressed in this study (11). One study sequenced the HFE, HJV, HAMP, TFR2 and SLC40A1 genes from 51 samples from Brazilian patients with J o u r n a l P r e -p r o o f primary IO.…”