Hereditary hyperferritinemia cataract syndrome in three unrelated families of western Greek origin caused by the C39 > G mutation of L-ferritin IRE

Brazilian family with hyperferritinemia-cataract syndrome: case report

Hereditary hyperferritinemia-cataract syndrome is a rare autosomal dominant disease caused by a genetic mutation in the iron responsive element in the 5' untranslated region of the ferritin light chain gene. Hereditary hyperferritinemia-cataract syndrome is characterized by elevated serum ferritin levels and bilateral cataract development early in life and may be misdiagnosed as hemochromatosis. This case report describes a Brazilian family with a clinical diagnosis of hereditary hyperferritinemia-cataract syndrome, which was submitted to ferritin light chain gene sequencing. The genetic mutation c.-164C>G was identified in the 5' untranslated region. In conclusion, genetic testing can be used for accurate diagnosis of hereditary hyperferritinemia-cataract syndrome to avoid misdiagnosis of hemochromatosis, other diseases associated with iron overload or ophthalmic diseases.

Ferritin L-subunit gene mutation and hereditary hyperferritinaemia cataract syndrome (HHCS): a case report and literature review

ABSTRACTObjectives: Hereditary hyperferritinaemia cataract syndrome (HHCS) is an autosomal dominant disease characterized by high serum ferritin levels and juvenile bilateral cataracts. It is often caused by mutations in the iron response element (IRE) of the ferritin L-subunit (FTL) gene. Here, we report a 73-year-old woman who presented to clinic with persistently elevated serum ferritin and family history of juvenile bilateral cataracts in four generations.Methods: Exome sequencing was used to identify the mutation of the FTL gene. Moreover, Sanger sequencing was performed to validate the mutation in the proband. We also reviewed the FLT gene mutations in published HHCS cases to provide experience for accurate diagnosis of similar patients.Results: A heterozygous mutation at position +33 (c.-167C > T, chr19:49468598) of the FTL gene was identified in the patient.Discussion: HHCS should be considered in the differential diagnosis of hyperferritinemia, especially in the presence of normal serum iron concentration and transferrin saturation.Conclusion: For patients with unexplained hyperferritinemia and bilateral cataracts who have experienced early vision loss, the establishment of genetic counseling is essential to diagnose other family members who are at risk in time.Abbreviations: FTL: ferritin L-subunit; HHCS: hereditary hyperferritinaemia cataract syndrome; IDT: integrated DNA technologies; IRE: iron response element; IRP: iron regulatory proteins; MRI: magnetic resonance imaging; SNV: single nucleotide variant; UTR: untranslated region.

A novel double nucleotide variant in the ferritin-L iron-responsive element in a Finnish patient with hereditary hyperferritinaemia-cataract syndrome

PURPOSE

To present a novel Finnish double nucleotide variant in the iron-responsive element (IRE) of the ferritin L-chain gene (FTL) leading to hyperferritinaemia-cataract syndrome (HHCS).

METHODS

Genomic DNA extracted from peripheral blood leucocytes and synthetized with three different primers flanking the IRE in the FTL 5'-untranslated region of the FTL was used in polymerase chain reaction (PCR). Thereafter, Sanger sequencing was performed on the 487-bp and 602-bp PCR amplification products with specific primers to reveal FTL IRE mutations.

RESULTS

A 58-year-old female patient with elevated serum ferritin level (1339 μg/l) was diagnosed with HHCS after extensive workup. Genetic testing identified a novel double point mutation g.48965355G>C (chr19, hg19) and g.48965356G>T (chr19, hg19) in the lower stem region of the IRE canonical structure of the FTL.

CONCLUSION

After excluding other causes, elevated serum ferritin level in a person with early onset cataract is indicative for HHCS, a genetic disorder caused by mutation in the IRE of the FTL.

Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder

The hereditary hyperferritinaemia-cataract syndrome (HHCS) is characterised by an autosomal dominant cataract and high levels of serum ferritin without iron overload. The cataract develops due to L-ferritin deposits in the lens and its pulverulent aspect is pathognomonic. The syndrome is caused by mutations within the iron-responsive element of L-ferritin. These mutations prevent efficient binding of iron regulatory proteins 1 and 2 to the IRE in L-ferritin mRNA, resulting in an unleashed ferritin translation. This paper reviews all 31 mutations (27 single nucleotide transitions and four deletions) that have been described since 1995. Laboratory test showing hyperferritinaemia, normal serum iron and normal transferrin saturation are indicative for HHCS after exclusion of other causes of increased ferritin levels (inflammation, malignancy, alcoholic liver disease) and should prompt an ophthalmological consultation for diagnostic confirmation. Invasive diagnostics such as liver biopsy are not indicated. HHCS is an important differential diagnosis of hyperferritinaemia. Haematologists, gastroenterologists and ophthalmologists should be aware of this syndrome to spare patients from further invasive diagnosis (liver biopsy), and also from a false diagnosis of hereditary haemochromatosis followed by venesections. Patients diagnosed with HHCS should be counselled regarding the relative harmlessness of this genetic disease, with early cataract surgery as the only clinical consequence.

High resolution melting for the identification of mutations in the iron responsive element of the ferritin light chain gene

BACKGROUND

Among the causes of hyperferritinemia, hereditary hyperferritinemia cataract syndrome (HHCS) is an autosomal dominant disease characterized by distinctive cataracts and high serum ferritin. It is caused by mutations in the iron responsive element (IRE) of the ferritin light chain gene (FTL).

METHODS

To speed up and simplify mutational scanning in this genomic region, we developed a protocol based on high-resolution melting (HRM) analysis.

RESULTS

Validation was carried out using 18 wild-type and 14 DNA samples carrying different mutations, each analyzed in replicates of 20. The method allowed for correct identification and genotyping of all mutant samples, and each variant generated a specific profile distinguishable from the wild type. A 5.5% proportion of false positive results were obtained. In addition, in two patients with HHCS, two new mutations were identified by HRM based on an altered melting profile. These mutations were subsequently characterized by direct sequencing (7C>G+40A>G and 49A>C).

CONCLUSIONS

The high reliability of HRM in detecting known and new DNA variations indicate that this could be an effective and sensitive method for molecular scanning of mutations in the IRE of the FTL gene in patients presenting with either HHCS or unexplained hyperferritinemia.

The case of a 1-year-old girl with hereditary hyperferritinemia cataract syndrome

Hereditary hyperferritinemia cataract syndrome (HHCS) is an autosomal dominant disorder characterized by high serum ferritin levels in the absence of iron overload accompanied by early onset of bilateral cataracts. The authors report the case of HHCS in a 1-year-old girl in a family of German origin. Routine blood examination revealed serum ferritin levels up to 2530 microg/L. Slit-lamp examination showed bilateral cataracts. HHCS should be considered in cases of high serum ferritin level and bilateral cataracts, which can even occur in pediatric patients. A liver biopsy and bone marrow aspiration are unnecessary diagnostic procedures in cases of HHCS and repeated phlebotomies are harmful.

Hereditary hyperferritinemia-cataract syndrome

Hereditary hyperferritinemia-cataract syndrome (HHCS) is a recently recognized syndrome characterized by dominantly inherited, early-onset cataracts and elevated serum ferritin. The opacities are caused by elevated ferritin protein within the crystalline lens and usually become symptomatic in the second to fourth decade of life. Routine laboratory tests can establish this diagnosis. We report two unrelated cases that presented in the United States.

Gene conversion mutation in crystallin, beta-B2 (CRYBB2) in a Chilean family with autosomal dominant cataract

PURPOSE

To map and identify the mutated gene for autosomal dominant cataract (ADC) in a large Chilean family (ADC53).

DESIGN

Experimental study.

PARTICIPANTS

Large Chilean family with ADCs.

METHODS

Linkage analyses using genome-wide polymorphic DNA markers were performed on a family with variable expression of cataracts to map the mutated gene to a chromosome; 2-point lod scores were calculated. Candidate genes in the region of the maximum lod score were sequenced. We compared haplotypes (alleles at closely linked markers) in families with previously reported mutations of the crystallin, beta-B2 gene (CRYBB2).

MAIN OUTCOME MEASURES

Identification of the causative mutation in the ADC53 family.

RESULTS

The ADC locus mapped to chromosome 22 in the region of a cluster of lens beta crystallin genes (CRYBB3, CRYBB2, CRYBB1, and CRYBA4 and the pseudogene CRYBB2P1). We sequenced CRYBB1 and CRYBB2 and found a previously reported mutation and a variant in exon 6 of CRYBB2 that cosegregate with the disease; these changes in CRYBB2 are in the reference (normal) sequence of an adjacent gene CRYBB2P1, a pseudogene. The haplotypes in the ADC53 Chilean family were different from the 2 previously reported families with the mutation.

CONCLUSIONS

The cataracts in the ADC53 Chilean family are caused by a mutation in the CRYBB2 gene; as the 2 variations in CRYBB2 are identical to the reference sequence of pseudogene CRYBB2P1, which has over 97% homology to CRYBB2, a gene conversion probably has occurred. Based on haplotype analyses, the mutation and variant are likely to be caused by independent gene conversions in our family and the previously reported families.