HFE-Related Hemochromatosis in a Chinese Patient: The First Reported Case

et al. 2021

Orphanet J Rare Dis

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Background Hereditary hemochromatosis (HH) is widely recognized and clinical manifestations of hemochromatosis-related (HFE-related) HH is well studied in European populations. Less is known about the clinical and laboratory characteristics of non-HFE related HH in Asian population. We aimed to explore the relationship between genotype and clinical phenotype in Chinese patients with non-HFE related hereditary hemochromatosis. Methods Peripheral blood samples and clinical data of patients with primary iron overload were collected from the China Registry of Genetic/Metabolic Liver Diseases. Sanger sequencing was performed in cases with primary iron overload, for 5 known HH related genes (HFE, HJV, HAMP, TFR2 and SLC40A1) and 2 novel iron homeostasis-related genes (DENND3 and SUGP2). The correlation of genotype and clinical phenotype in these patients was analyzed. Results Of the 32 patients with primary iron overload (23 were males and 9 were females), non-HFE variants were detected in 31 (31/32, 97%), including 8 pathogenic variants in HJV, 7 pathogenic variants in SLC40A1, 8 likely pathogenic variants in SUGP2 and 5 likely pathogenic variants in DENND3 cases. Among these 31 cases, 4 cases harbored homozygous variants, 2 cases harbored homozygous + heterozygous variants, 19 cases harbored heterozygous or combined heterozygous variants, and 6 cases harbored no any damaging variants. None of investigated cases carried damaging HAMP and TFR2 variants were found. 8 cases were classified as type 2A HH and 6 cases as type 4 HH, 10 cases as non-classical genotype, and 6 cases had no pathogenic variants from 31 cases. During the statistical analysis, we excluded one case (SLC40A1 IVS3 + 10delGTT + SUGP2 p. R639Q(homo)) with difficulty in grouping due to combined damaging variants. Cases with type 2A HH have an earlier age at diagnosis (p = 0.007). The iron index of cases in type 2A HH and type 4 HH was higher than that in other groups (p = 0.01). Arthropathy was relatively rare in all groups. None of cases with type 2A HH developed cirrhosis. Cirrhosis and diabetes are more prevalent in type 4 HH. The incidence of cirrhosis (p = 0.011), cardiac involvement (p = 0.042), diabetes (p = 0.035) and hypogonadism (p = 0.020) was statistically significant in the four groups. However, due to the limited sample size, the pairwise comparison showed no significant difference. Conclusions This is the first comprehensive analysis about the gene variant spectrum and phenotypic aspects of non-HFE HH in China. The results will be useful to the identification, diagnosis and management of HH in China.

Section: Discussionsupporting

confidence: 64%

Correlation of genotype and phenotype in 32 patients with hereditary hemochromatosis in China

et al. 2021

Orphanet J Rare Dis

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“…Our group have identified recently several mutations in non- HFE genes in HH, including HJV p.E3D, p.H104R, and p.V274M, TFR2 p.A302E and p.L745R, and SLC40A1 p.Y333H [ 5 , 11 ]. We further identified other novel genetic variants in genes involved in iron metabolism, such as TMPRSS6 p.T331M, BMP4 p.R269Q, SUGP2 p.R639Q and DENND3 p.L708V [ 5 ], and specifically we identified the first HH case with compound heterozygosity p.C282Y/p.R71X in HFE [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

Identification of novel non-HFE mutations in Chinese patients with hereditary hemochromatosis

Li²,

Xu³

et al. 2022

Orphanet J Rare Dis

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Backgrounds Hereditary hemochromatosis (HH) is mainly caused by homozygous p.C282Y mutations in HFE in the Caucasians. We recently reported non-HFE mutations constitute the major cause of HH in Chinese. However, there is still a relatively high proportion of cases with primary iron overload from unexplained causes. We aimed to explore novel non-HFE mutations in Chinese patients with primary iron overload. Methods Whole exome sequence was conducted to screen mutations in novel HH-related genes in the 9 cases with unexplained primary iron overload. Then the representative candidate genes were screened for mutations in another cohort of 18 HH cases. The biological function of the selected genes and variants were analyzed in vitro. Results Whole exome sequencing of 9 cases with unexplained primary iron overload identified 42 missense variants in 40 genes associated with iron metabolism pathway genes such as UBE2O p.K689R and PCSK7 p.R711W. Subsequent Sanger sequencing of the UBE2O and PCSK7 genes in the 27 cases with primary iron overload identified p.K689R in UBE2O, p.R711W and p.V143F in PCSK7 at frequency of 2/27,1/27 and 2/27 respectively. In vitro siRNA interference of UBE2O and PCSK7 resulted in down-regulated HAMP mRNA expression. Adenovirus generation of UBE2O p.K689R in cell lines resulted in increased expression of SMAD6 and SMAD7 and downregulation of p-SMAD1/5 and HAMP expression, and the reduction of hepcidin level. Conclusions Our study identified a series of novel candidate non-HFE mutations in Chinese patients with HH. These may provide insights into the genetic basis of unexplained primary iron overload.

“…Our group have identi ed recently several mutations in non-HFE genes in HH, including HJV p.E3D, p.H104R, and p.V274M, TFR2 p.A302E and p.L745R, and SLC40A1 p.Y333H [5,11]. We further identi ed other novel genetic variants in genes involved in iron metabolism, such as TMPRSS6 p.T331M, BMP4 p.R269Q, SUGP2 p.R639Q and DENND3 p.L708V [5], and speci cally we identi ed the rst HH case with compound heterozygosity p.C282Y/p.R71X in HFE [12].…”

Section: Introductionmentioning

confidence: 99%

Identification of Novel Non-HFE Mutations in Chinese Patients with Hereditary Hemochromatosis

et al. 2022

Preprint

Self Cite

Backgrounds : Hereditary hemochromatosis (HH) is mainly caused by homozygous p.C282Y mutations in HFE in the Caucasians. We recently reported non-HFE mutations constitute the major cause of HH in Chinese. However, there is still a relatively high proportion of cases with primary iron overload from unexplained causes. We aimed to explore novel non-HFE mutations in Chinese patients with primary iron overload. Methods Whole exome sequence was conducted to screen mutations in novel HH-related genes in the 9 cases with unexplained primary iron overload. Then the representative candidate genes were screened for mutations in another cohort of 18 HH cases. The biological function of the selected genes and variants were analyzed in vitro. Results Whole exome sequencing of 9 cases with unexplained primary iron overload identified 42 missense variants in 40 genes associated with iron metabolism pathway genes such as UBE2O p.K689R and PCSK7 p.R711W. Subsequent Sanger sequencing of the UBE2O and PCSK7 genes in the 27 cases with primary iron overload identified p.K689R in UBE2O, p.R711W and p.V143F in PCSK7 at frequency of 2/27,1/27 and 2/27 respectively. In vitro siRNA interference of UBE2O and PCSK7 resulted in down-regulated HAMP mRNA expression. Adenovirus generation of UBE2O p.K689R in cell lines resulted in increased expression of SMAD6 and SMAD7 and downregulation of p-SMAD1/5 and HAMP expression, and the reduction of hepcidin level. Conclusions Our study identified a series of novel candidate non-HFE mutations in Chinese patients with HH. These may provide insights into the genetic basis of unexplained primary iron overload.