Hereditary hyperferritinemia-cataract syndrome (HHCS) is an autosomal dominant disorder caused by non-coding point mutations or small deletions in the iron-responsive element (IRE) in the 5' untranslated region of FTL. The IRE is the stem-loop that iron-regulatory proteins IRP1 and IRP2 occupy when cellular iron is low, blocking assembly of the translation preinitiation complex on L-ferritin mRNA. Variants that distort the hairpin lower or abolish IRP affinity, so L-ferritin translation runs constitutively and is no longer coupled to iron supply. The result is a very high serum ferritin with a normal serum iron and a normal transferrin saturation, and no parenchymal iron loading, together with bilateral early-onset cataract produced by crystalline L-ferritin deposits in lens fibre cells. Clinically the disorder is benign apart from the lens, and its main hazard is iatrogenic: because serum ferritin is routinely read as a surrogate for body iron stores, HHCS is repeatedly mistaken for hereditary haemochromatosis and treated with venesection or iron chelation, which cannot lower a genetically driven ferritin and instead produces iron deficiency. This entry is mechanistically distinct from `kb/disorders/neuroferritinopathy.yaml`, which is caused by FTL coding-region variants and features brain iron accumulation with low-to-normal serum ferritin.
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Conditions with similar clinical presentations that must be differentiated from Hereditary Hyperferritinemia with Congenital Cataracts:
name: Hereditary Hyperferritinemia with Congenital Cataracts
creation_date: '2026-09-05T18:30:00Z'
category: Mendelian
description: >-
Hereditary hyperferritinemia-cataract syndrome (HHCS) is an autosomal dominant
disorder caused by non-coding point mutations or small deletions in the
iron-responsive element (IRE) in the 5' untranslated region of FTL. The IRE is
the stem-loop that iron-regulatory proteins IRP1 and IRP2 occupy when cellular
iron is low, blocking assembly of the translation preinitiation complex on
L-ferritin mRNA. Variants that distort the hairpin lower or abolish IRP
affinity, so L-ferritin translation runs constitutively and is no longer
coupled to iron supply. The result is a very high serum ferritin with a normal
serum iron and a normal transferrin saturation, and no parenchymal iron
loading, together with bilateral early-onset cataract produced by crystalline
L-ferritin deposits in lens fibre cells. Clinically the disorder is benign apart
from the lens, and its main hazard is iatrogenic: because serum ferritin is
routinely read as a surrogate for body iron stores, HHCS is repeatedly
mistaken for hereditary haemochromatosis and treated with venesection or iron
chelation, which cannot lower a genetically driven ferritin and instead
produces iron deficiency. This entry is mechanistically distinct from
`kb/disorders/neuroferritinopathy.yaml`, which is caused by FTL coding-region
variants and features brain iron accumulation with low-to-normal serum
ferritin.
disease_term:
preferred_term: hereditary hyperferritinemia with congenital cataracts
term:
id: MONDO:0010952
label: hereditary hyperferritinemia with congenital cataracts
synonyms:
- hereditary hyperferritinemia-cataract syndrome
- hyperferritinemia-cataract syndrome
- hereditary hyperferritinaemia cataract syndrome
- Bonneau-Beaumont syndrome
- HHCS
parents:
- hereditary disease
- eye disorder
- inherited disorder of iron metabolism
classifications:
harrisons_chapter:
- classification_value: ONCOLOGY_HEMATOLOGY
notes: >-
Almost every case is ascertained in a haematology, hepatology or general
medical clinic during the work-up of an unexplained high serum ferritin,
and the entity's practical importance is as a differential diagnosis of
hyperferritinaemia rather than as an eye disease.
- classification_value: GENETICS_ENVIRONMENT_DISEASE
notes: >-
A Mendelian dominant disorder whose lesion is a non-coding cis-regulatory
element, which is also why coding-only gene panels miss it.
icimd_category:
- classification_value: iron_metabolism
notes: >-
Assigned by analogy with the other inherited disorders of iron-protein
handling curated here (see `kb/disorders/IRIDA_Syndrome.yaml`). Note the
qualification that matters clinically: HHCS deranges the regulation of an
iron-storage protein, not iron flux itself, and body iron is normal.
inheritance:
- name: Autosomal dominant inheritance
inheritance_term:
preferred_term: Autosomal dominant inheritance
term:
id: HP:0000006
label: Autosomal dominant inheritance
description: >-
Heterozygous FTL IRE variants segregate with both the hyperferritinaemia and
the cataract through multiple generations. A negative family history does not
exclude the diagnosis, because de novo variants occur. Rare homozygous
individuals have been reported, and in at least one consanguineous family the
homozygote had a markedly higher serum ferritin and the most severe cataract,
indicating an allele-dose effect rather than a distinct recessive disease.
evidence:
- reference: PMID:7492760
reference_title: "Molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome: a mutation in the iron-responsive element of ferritin L-subunit gene (the \"Verona mutation\")."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "clinically characterized by the combination of elevated serum ferritin and congenital bilateral nuclear cataract, both cotransmitted as an autosomal dominant trait"
explanation: The original clinical description establishes co-transmission of both features as a dominant trait.
- reference: PMID:33221470
reference_title: "Hereditary hyperferritinemia-cataract syndrome in three Czech families: molecular genetic testing and clinical implications."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Lack of family history does not exclude HHCS, because the pathogenic variant can arise de novo."
explanation: Documents a paternity-confirmed de novo variant, so absence of an affected parent does not rule the diagnosis out.
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The zygosity of the mutation, occurring in homozygous and heterozygous state in the proband and other affected family members respectively, correlated well with severity of ophthalmological and hematological manifestations."
explanation: Supports an allele-dose effect in the rare homozygous state within an otherwise dominant disorder.
prevalence:
- population: Worldwide
measure_type: POINT_PREVALENCE
prevalence_class: BAND_1_9_PER_1000000
rate_per_100000: 0.5
notes: >-
The commonly quoted 1 in 200,000 figure is an expert estimate repeated across
reviews, not a population-screening measurement, and every source that quotes
it also says it is probably an underestimate because the disorder is
misclassified as haemochromatosis. 1 in 200,000 is 0.5 per 100,000.
evidence:
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The estimated prevalence of HHCS is around 1 in 200,000 individuals, though this is likely underestimated due to underdiagnosis, especially in milder or subclinical cases"
explanation: States the prevalence estimate and its own caveat, which is why the record is written as an estimate.
- population: Worldwide
measure_type: CASES_IN_LITERATURE
prevalence_class: ULTRA_RARE
notes: >-
Two independent counts of the published corpus a few years apart give a
consistent picture of a few hundred reported kindreds at most.
evidence:
- reference: PMID:29426274
reference_title: "FTL c.-168G>C Mutation in Hereditary Hyperferritinemia Cataract Syndrome: A New Italian Family."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "About 160 families/unrelated cases with HHCS are known worldwide."
explanation: A direct count of the reported world literature at the time of publication.
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Fewer than 200 families have been reported worldwide, often identified incidentally during evaluation of unexplained hyperferritinemia"
explanation: A more recent count, consistent with the earlier one, and it names incidental ascertainment as the usual route.
pathophysiology:
- name: FTL Iron-Responsive Element Disruption
description: >-
The initiating lesion is a heterozygous single-nucleotide substitution or
short deletion inside the ~30-nucleotide IRE hairpin encoded in the FTL 5'
untranslated region. The IRE has four structural parts that matter: a
conserved CAGUGN apical hexanucleotide loop, an upper stem, an unpaired
cytosine bulge separating the stems, and a lower stem. Pathogenic changes
cluster in the loop, the bulge and the upper stem, and act by distorting or
destabilising the hairpin so that it no longer presents the surface that
iron-regulatory proteins recognise. The FTL coding sequence is untouched, so
the L-ferritin protein produced is structurally normal - which is what
separates this disorder from the coding-region FTL diseases.
biological_scale: MOLECULAR
mechanism_confidence: ESTABLISHED
genes:
- preferred_term: FTL
term:
id: hgnc:3999
label: FTL
genetic_context:
variant_origin: GERMLINE
zygosity: HETEROZYGOUS
description: >-
Constitutional non-coding variant in the FTL 5' UTR. Almost all reported
patients are heterozygous; a handful of homozygous individuals have been
described in consanguineous families. Deliberately no
functional_impact_category is asserted here: the enum describes the
activity of a gene product, and this variant does not change the product
at all, only the amount of it that is made. The variant-level claim is
carried instead by `regulatory_category` on the entries in `genetic`.
evidence:
- reference: PMID:7492760
reference_title: "Molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome: a mutation in the iron-responsive element of ferritin L-subunit gene (the \"Verona mutation\")."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This mutation involves the five nucleotides sequence [CAGUG] of the iron-responsive element (IRE), which is critical for the posttranscriptional regulation of ferritin synthesis by means of IRE-binding protein (IRE-BP)."
explanation: Identifies the conserved apical loop of the FTL IRE as the site of the founding mutation and states its regulatory role.
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The most important sequences are a highly conserved hexanucleotide at the terminal loop, a bulge with an unpaired cytidin, and the upper stem of the hairpin"
explanation: A survey of all mutations then reported localises the pathogenic changes to the loop, bulge and upper stem, which is the basis for the structural claim in this node.
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Twenty-seven of these mutations are single nucleotide transitions and four are deletions of 2-29 base pairs."
explanation: Establishes that the allelic spectrum is substitutions plus short deletions, not coding changes.
downstream:
- target: Loss of Iron-Regulatory Protein Binding to the FTL IRE
causal_link_type: DIRECT
description: >-
A distorted hairpin no longer forms a high-affinity IRP-binding surface.
evidence:
- reference: PMID:7493028
reference_title: Mutation in the iron responsive element of the L ferritin mRNA in a family with dominant hyperferritinaemia and cataract.
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "We show that this mutation abolishes the binding of IRP in vitro and leads to a high constitutive, poorly regulated L-ferritin synthesis in cultured lymphoblastoid cells established from affected patients."
explanation: Directly demonstrates that the IRE mutation is what abolishes IRP binding, which is the claim this edge makes.
- name: Loss of Iron-Regulatory Protein Binding to the FTL IRE
description: >-
In health, when cytosolic iron is low, IRP1 (in its apo, non-cluster form)
and IRP2 bind the FTL IRE with high affinity and prevent recruitment of the
small ribosomal subunit, so L-ferritin is not made. HHCS variants reduce that
affinity. The reduction is graded rather than all-or-none: gel-shift assays
across the allelic series show a spectrum from near-complete abolition to a
partial, several-fold loss of affinity, and even a partial loss is enough to
cause disease. This graded biochemistry is the mechanistic substrate for the
clinical observation that different IRE positions give different disease
severities.
biological_scale: MOLECULAR
mechanism_confidence: ESTABLISHED
molecular_functions:
- preferred_term: iron-responsive element binding by IRP1 and IRP2
term:
id: GO:0030350
label: iron-responsive element binding
modifier: DECREASED
evidence:
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: OTHER
snippet: "Under conditions of intracellular iron depletion, both IRPs can bind IRE with high affinity, prevent binding of the translation initiation complex and thus block ferritin translation"
explanation: States the normal repressive function this node reports the loss of. Graded OTHER because the source is a review summarising the physiology rather than reporting a study.
- reference: PMID:9226182
reference_title: "Hereditary hyperferritinemia-cataract syndrome: relationship between phenotypes and specific mutations in the iron-responsive element of ferritin light-chain mRNA."
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Using a gel retardation assay, the observed molecular lesions were shown to variably reduce the IRE affinity for an iron regulatory protein (IRP), which inhibits ferritin mRNA translation."
explanation: Demonstrates directly, and across more than one allele, that the lesions reduce IRE-IRP affinity, and that the reduction is variable.
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "the WT IRE has an KDapp of 0.50 nM, while the +49A > G mutant IRE demonstrates a more than 5-fold lower affinity for IRP1, with an KDapp of 2.70 nM"
explanation: Quantifies the affinity loss for one allele and shows it is partial, supporting the graded rather than all-or-none reading of this step.
downstream:
- target: Constitutive Derepression of L-Ferritin Translation
causal_link_type: DIRECT
description: >-
Without IRP occupancy the preinitiation complex assembles on FTL mRNA
irrespective of iron supply.
evidence:
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: OTHER
snippet: "abrogating the IRP/IRE interaction and leading to uncontrolled translation of FTL mRNA, independent of the iron status."
explanation: States the causal step from lost IRP binding to iron-independent translation.
- name: Constitutive Derepression of L-Ferritin Translation
description: >-
Translation initiation on FTL mRNA becomes constitutive. This is the
qualitative change that defines the disorder: the process is not simply
running faster, it has been removed from the regulatory circuit that normally
couples it to cytosolic iron, so neither iron loading nor iron chelation of
the cell moves it. HHCS is the founding example of what has been called
translational pathophysiology - disease caused by a mutation that changes how
efficiently an mRNA is translated rather than what it encodes.
biological_scale: MOLECULAR
mechanism_confidence: ESTABLISHED
biological_processes:
- preferred_term: iron-independent initiation of L-ferritin mRNA translation
term:
id: GO:0006413
label: translational initiation
modifier: GAIN_OF_FUNCTION
- preferred_term: IRP-mediated translational repression of FTL mRNA
term:
id: GO:0045947
label: negative regulation of translational initiation
modifier: LOSS_OF_FUNCTION
evidence:
- reference: PMID:10828006
reference_title: "Translational pathophysiology: a novel molecular mechanism of human disease."
supports: SUPPORT
evidence_source: OTHER
snippet: "Hereditary hyperferritinemia/cataract syndrome arises from various point mutations or deletions within a protein-binding sequence in the 5'-UTR of the L-ferritin mRNA. Each unique mutation confers a characteristic degree of hyperferritinemia and severity of cataract in affected individuals."
explanation: Frames HHCS as a translational-control disease and states the allele-specific dose relationship. Graded OTHER because this is a conceptual review rather than a primary study.
- reference: PMID:9596665
reference_title: Analysis of ferritins in lymphoblastoid cell lines and in the lens of subjects with hereditary hyperferritinemia-cataract syndrome.
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "Enzyme-linked immunosorbent assays specific for the H- and L-type ferritins showed that L-ferritin levels were up to 20-fold higher in HHCS than in control cells and were not affected by iron supplementation or chelation."
explanation: The unresponsiveness to both iron loading and chelation is the direct demonstration that translation has left the regulatory circuit, which is why this node is graded qualitatively rather than as a simple increase.
downstream:
- target: L-Ferritin Overproduction and Intracellular Accumulation
causal_link_type: DIRECT
evidence:
- reference: PMID:34064225
reference_title: "Hereditary Hyperferritinemia Cataract Syndrome: Ferritin L Gene and Physiopathology behind the Disease-Report of New Cases."
supports: SUPPORT
evidence_source: OTHER
snippet: "Mutations in the FTL IRE abrogate the interaction of FTL mRNA with the IRPs, and de-repress the expression of FTL protein. Subsequently, there is an overproduction of ferritin that accumulates in serum (hyperferritinemia) and excess ferritin precipitates in the lens, producing cataracts."
explanation: States the step from derepressed translation to protein overproduction, and onward to both downstream branches of this pathograph.
- name: L-Ferritin Overproduction and Intracellular Accumulation
description: >-
Cells accumulate five- to twenty-fold excess L-ferritin. Because the excess is
of one subunit only, the assembled product is abnormal in composition rather
than in structure: roughly half of the surplus L-chain assembles into
L-chain-only 24-mer homopolymers, which lack the H-subunit ferroxidase centre
and therefore do not take up iron at all, and the remainder shifts the normal
heteropolymer population towards L-rich isoferritins. This is the reason the
disorder does not cause iron overload despite an enormous ferritin burden -
the extra shells are essentially empty.
biological_scale: CELLULAR
mechanism_confidence: ESTABLISHED
cellular_components:
- preferred_term: L-chain-rich and L-chain-only ferritin shells
term:
id: GO:0070288
label: ferritin complex
modifier: INCREASED
evidence:
- reference: PMID:9596665
reference_title: Analysis of ferritins in lymphoblastoid cell lines and in the lens of subjects with hereditary hyperferritinemia-cataract syndrome.
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "in HHCS cells a large proportion of L-ferritin accumulates as nonfunctional L-chain 24 homopolymers"
explanation: Establishes the L-chain homopolymer species that carries the excess.
- reference: PMID:9596665
reference_title: Analysis of ferritins in lymphoblastoid cell lines and in the lens of subjects with hereditary hyperferritinemia-cataract syndrome.
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "the concomitant fivefold to 10-fold expansion of ferritin heteropolymers, with a shift to L-chain-rich isoferritins, does not have major effects on cellular iron metabolism"
explanation: Supports both the compositional shift and the crucial negative claim that cellular iron handling is left intact.
- reference: PMID:36768886
reference_title: Hereditary Hyperferritinemia.
supports: SUPPORT
evidence_source: OTHER
snippet: "leading to constitutive up-regulation of L-ferritin, intracellular accumulation of ferritin, mainly in the form of the homopolymers H0-L24, and hyperferritinemia"
explanation: A recent review states the same subunit composition and links it forward to the hyperferritinaemia. Graded OTHER because it is a review synthesis.
downstream:
- target: Serum Hyperferritinemia Uncoupled from Body Iron Stores
causal_link_type: DIRECT
description: >-
Circulating ferritin is a by-product of intracellular L-ferritin synthesis
and secretion, so it tracks the intracellular excess.
evidence:
- reference: PMID:9226182
reference_title: "Hereditary hyperferritinemia-cataract syndrome: relationship between phenotypes and specific mutations in the iron-responsive element of ferritin light-chain mRNA."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "There was a close relationship between mononuclear cell L-type ferritin content and serum ferritin concentration (r = 0.95, P < .00001), suggesting that the excess production of ferritin in cells was directly responsible for the hyperferritinemia."
explanation: A quantitative within-patient correlation establishing that the serum level is driven by the intracellular excess rather than by leakage from damaged tissue.
- target: Lens Fibre Cell L-Ferritin Accumulation
causal_link_type: DIRECT
description: >-
The same derepression operates in the lens, where FTL is transcribed more
heavily than in surrounding ocular tissue.
evidence:
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: OTHER
snippet: "Interestingly, it has been demonstrated that endogenous FTL transcription is significantly higher in the lens compared to other eye tissues, which is likely to contribute to the pathogenic levels of FTL deposits found in HHCS lenses"
explanation: Offers the tissue-level reason the systemic derepression lands hardest on the lens, which is what this edge asserts.
- name: Serum Hyperferritinemia Uncoupled from Body Iron Stores
description: >-
Serum ferritin is persistently and often markedly elevated, commonly in the
several-hundred to greater-than-2,000 microgram/L range, while serum iron,
transferrin saturation, total iron-binding capacity and parenchymal iron
content stay normal. The clinically decisive point is negative: this is not
iron overload. Serum ferritin has simply stopped being an index of body iron
in these patients, in both directions - it will also fail to fall when they
become genuinely iron deficient.
biological_scale: ORGANISM
mechanism_confidence: ESTABLISHED
evidence:
- reference: PMID:7492760
reference_title: "Molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome: a mutation in the iron-responsive element of ferritin L-subunit gene (the \"Verona mutation\")."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Differently from subjects with hereditary hemochromatosis, they have normal to low levels of serum iron and percent of transferrin saturation and absence of iron overload in parenchymal organs."
explanation: States the dissociation between the ferritin level and every other index of body iron.
- reference: PMID:41769540
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome Misdiagnosed as Iron Overload: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "While typically elevated in hereditary hemochromatosis, transferrin saturation remains normal in HHCS, reflecting preserved systemic iron homeostasis"
explanation: Names transferrin saturation as the discriminating measurement and states that systemic iron homeostasis is preserved.
- reference: PMID:36768886
reference_title: Hereditary Hyperferritinemia.
supports: SUPPORT
evidence_source: OTHER
snippet: "In patients with HHCS, serum ferritin is no longer a reliable indicator of iron stores in both iron deficiency and iron overload, which is something to keep in mind."
explanation: Supports the bidirectional statement in this node's description, including the under-recognised risk of missing true iron deficiency.
downstream:
- target: Persistent Hyperferritinemia
causal_link_type: DIRECT
- target: Iatrogenic Iron Depletion from Misdirected Venesection and Chelation
causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
description: >-
The intervening step is not biological but interpretive: the high ferritin
is read as evidence of iron overload and treated as haemochromatosis.
intermediate_mechanisms:
- Misattribution of isolated hyperferritinaemia to hereditary haemochromatosis
evidence:
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Many patients are initially misdiagnosed with hereditary haemochromatosis and treated with venesections that lead to rapid iron depletion and iron-deficiency anaemia."
explanation: States the whole edge, including both its interpretive intermediate step and its harmful endpoint.
- name: Lens Fibre Cell L-Ferritin Accumulation
description: >-
Lens fibre cells accumulate L-ferritin far in excess of any other tissue
examined. Measured lens L-ferritin content in HHCS ranges from about ten-fold
the control value in one extracted nucleus to roughly 1500-fold in two others,
the spread reflecting different assays, cataract morphologies and ages at
surgery. Two features of the lens plausibly explain why this is the one tissue
that suffers: FTL transcription is unusually high there, and lens fibre cells
are post-mitotic, organelle-free and protein-packed, with no way to dilute or
turn over an accumulating protein. The tissue selectivity is nonetheless not
formally resolved - see the knowledge gap recorded in `discussions`.
biological_scale: CELLULAR
conforms_to: "cataract_lens_opacification#Lens Homeostasis Insult"
mechanism_confidence: ESTABLISHED
cell_types:
- preferred_term: lens fibre cell
term:
id: CL:0011004
label: lens fiber cell
locations:
- preferred_term: lens of the eye
term:
id: UBERON:0000965
label: lens of camera-type eye
evidence:
- reference: PMID:9596665
reference_title: Analysis of ferritins in lymphoblastoid cell lines and in the lens of subjects with hereditary hyperferritinemia-cataract syndrome.
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "In addition, we analyzed the lens recovered from cataract surgery of a HHCS patient. We found it to contain about 10-fold more L-ferritin than control lens."
explanation: Direct measurement of L-ferritin excess in an HHCS lens.
- reference: PMID:11703332
reference_title: "Clinical, biochemical and molecular findings in a series of families with hereditary hyperferritinaemia-cataract syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The lens ferritin content was analysed in two subjects who underwent cataract surgery at different ages, with different cataract morphology. Values were similar and about 1500-fold higher than in controls."
explanation: A second, much larger measurement in two further lenses, and the source of the upper end of the range quoted here.
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: OTHER
snippet: "Although ferritin accumulates in all cell types of HHCS patients, it turns out to be toxic only in the crystallin-containing lens fiber cells."
explanation: States the tissue selectivity that makes this a distinct node rather than a restatement of the systemic overproduction.
downstream:
- target: Crystalline L-Ferritin Deposition and Lens Light Scattering
causal_link_type: DIRECT
evidence:
- reference: PMID:10873976
reference_title: The lens in hereditary hyperferritinaemia cataract syndrome contains crystalline deposits of L-ferritin.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This unusual finding of crystalline opacities in the lens may be unique to HHCS and is likely to result from disturbed metabolism of L-ferritin within the lens or an abnormal interaction between L-ferritin and lens proteins."
explanation: Attributes the crystalline opacities specifically to the excess lens L-ferritin, which is the claim this edge makes.
- name: Crystalline L-Ferritin Deposition and Lens Light Scattering
description: >-
The excess L-ferritin comes out of solution as discrete crystalline inclusions
within the lens substance. Immunohistochemistry on an extracted HHCS lens
stains these inclusions for L-ferritin and not for H-ferritin, so they are
made of the overproduced subunit itself. Refractive-index discontinuities at
the inclusions scatter incident light and degrade the image reaching the
retina. Levi and colleagues additionally proposed that the L-chain excess
perturbs the solubility equilibrium among the crystallins, or the lens
antioxidant balance, as a contributing mechanism; that proposal has not been
tested directly and is recorded here as a hypothesis rather than as the
established route.
biological_scale: TISSUE
conforms_to: "cataract_lens_opacification#Loss of Lens Refractive Transparency and Light Scattering"
mechanism_confidence: ESTABLISHED
cell_types:
- preferred_term: lens fibre cell
term:
id: CL:0011004
label: lens fiber cell
notes: >-
Conformance caveat. The `cataract_lens_opacification` module routes its
initiating insult through two crystallin-centred nodes - loss of crystallin
solubility, then high-molecular-weight crystallin aggregate deposition -
before reaching the light-scattering node this entry conforms to. HHCS
largely bypasses that pair: the deposits are crystals of an overproduced
non-crystallin protein, not aggregates of the crystallins themselves. The
conformance is therefore declared at the two ends of the module chain, the
lens insult and the optical consequence, and deliberately not at the
crystallin-aggregation intermediate. Whether the crystallins are involved at
all is exactly the untested part of the Levi hypothesis noted in this node's
description.
evidence:
- reference: PMID:10873976
reference_title: The lens in hereditary hyperferritinaemia cataract syndrome contains crystalline deposits of L-ferritin.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The cataract comprised discrete crystalline inclusions with positive staining with anti-L-ferritin but not anti-H-ferritin."
explanation: Establishes both the crystalline morphology of the deposits and their L-ferritin composition.
- reference: PMID:10873976
reference_title: The lens in hereditary hyperferritinaemia cataract syndrome contains crystalline deposits of L-ferritin.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The HHCS lens L-ferritin content was 147 microg/g dry weight of lens compared with <16 microg/g for a non-HHCS control cataract lens."
explanation: Quantifies the lens burden against a cataractous non-HHCS control, so the excess is not simply a feature of any cataract.
- reference: PMID:36768886
reference_title: Hereditary Hyperferritinemia.
supports: SUPPORT
evidence_source: OTHER
snippet: "Lens opacity probably results from overproduction of L-type ferritin, as shown by the presence of light-diffracting crystalline deposits rich in L-ferritin in cataractous lenses from individuals with HHCS"
explanation: States the optical step - light diffraction by the deposits - that this node asserts. Graded OTHER because it is a review synthesis.
- reference: PMID:9596665
reference_title: Analysis of ferritins in lymphoblastoid cell lines and in the lens of subjects with hereditary hyperferritinemia-cataract syndrome.
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "L-chain accumulation occurs also in the lens, where it may induce cataract formation by altering the delicate equilibrium between other water-soluble proteins (ie, crystallins) and/or the antioxidant properties."
explanation: The source of the crystallin-equilibrium hypothesis recorded in this node's description; note the authors state it as a possibility, not a finding.
downstream:
- target: Bilateral Early-Onset Cataract
causal_link_type: DIRECT
- target: Pulverulent Lens Opacities
causal_link_type: DIRECT
- name: Iatrogenic Iron Depletion from Misdirected Venesection and Chelation
description: >-
The commonest complication of HHCS is not caused by the disease. Because the
ferritin elevation is generated by translation and not by stored iron,
removing iron cannot correct it; what venesection does instead is strip a
normal iron store from a patient who had one, producing iron deficiency and
microcytic anaemia while the ferritin stays high. Iron chelation carries its
own hazard: one 8.5-year-old treated with deferasirox on a mistaken diagnosis
of iron overload developed life-threatening acute hyperammonaemia. Repeated
liver biopsy for the same misdiagnosis is a further avoidable harm. This node
is included in the pathograph because the harm is mechanistically predictable
from the upstream biology, not because it is a property of the genotype.
biological_scale: ORGANISM
mechanism_confidence: ESTABLISHED
evidence:
- reference: PMID:7492760
reference_title: "Molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome: a mutation in the iron-responsive element of ferritin L-subunit gene (the \"Verona mutation\")."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "When unnecessary phlebotomies are performed, they rapidly develop iron-deficient anemia, with persistently elevated levels of serum ferritin."
explanation: The original description already recorded both halves of the harm - the induced anaemia and the failure of the ferritin to fall.
- reference: PMID:33221470
reference_title: "Hereditary hyperferritinemia-cataract syndrome in three Czech families: molecular genetic testing and clinical implications."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "One individual, aged 43 years, underwent phlebotomy; another, aged 8.5 years, was treated with the iron chelator deferasirox, leading to life-threatening acute hyperammonemia, without severe liver injury."
explanation: Documents the chelation arm of the harm and its severity in a specific patient.
- reference: PMID:41769540
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome Misdiagnosed as Iron Overload: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This intervention did not result in any clinically meaningful reduction in serum ferritin levels, supporting the absence of true iron overload."
explanation: An observed instance of the futility of venesection in HHCS, which is the mechanistic point of this node.
- reference: PMID:30678075
reference_title: "L-Ferritin: One Gene, Five Diseases; from Hereditary Hyperferritinemia to Hypoferritinemia-Report of New Cases."
supports: SUPPORT
evidence_source: OTHER
snippet: "Some patients have received unnecessary invasive diagnostic techniques, such as liver biopsy, and are inappropriately treated with venesections and phlebotomies that can cause severe iron-deficiency anemia."
explanation: Adds the invasive-diagnostic arm of the same harm pathway. Graded OTHER because it is a review that also reports new cases; the statement quoted is the review's synthesis.
downstream:
- target: Iron Deficiency Anemia
causal_link_type: DIRECT
phenotypes:
- category: Ophthalmologic
name: Bilateral Early-Onset Cataract
description: >-
Bilateral, generally symmetrical lens opacity, classically nuclear and often
described as congenital. In practice the timing is variable: opacities may be
present in infancy, first detected in childhood or adolescence, or not
recognised until adult life. Two reported children extend that range past
delay to absence: a newborn known to carry the variant had no detectable lens
opacity at birth or at one year, and a separate paediatric proband had no
lenticular opacities at all at the point of diagnosis and was placed under
surveillance rather than treated. The cataract is slowly
progressive and eventually requires extraction in most affected people. Age at
diagnosis and at surgery vary widely both between and within families sharing
the same allele.
frequency: VERY_FREQUENT
diagnostic: true
phenotype_term:
preferred_term: Bilateral early-onset cataract
term:
id: HP:0000519
label: Developmental cataract
laterality: BILATERAL
clinical_course: PROGRESSIVE
evidence:
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Clinically, aside from isolated hyperferritinemia, the hallmark manifestation is progressive, bilateral cataract formation, usually developing in childhood or adolescence and often requiring surgical intervention"
explanation: Supports the bilaterality, the early onset, the progressive course and the frequent need for surgery.
- reference: PMID:15280904
reference_title: Clinical features and molecular analysis of seven British kindreds with hereditary hyperferritinaemia cataract syndrome.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "We report the clinical features of seven HHCS kindreds containing 49 individuals with premature cataract."
explanation: The largest reported clinical series, establishing premature cataract as the constant clinical feature across kindreds.
- reference: PMID:11703332
reference_title: "Clinical, biochemical and molecular findings in a series of families with hereditary hyperferritinaemia-cataract syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "A marked phenotypic variability was observed, particularly with regard to ocular involvement (i.e. age range at which cataract was diagnosed in 16 subjects with the C39T: 6-40 years)."
explanation: Quantifies the within-allele variability in age at diagnosis stated in this description.
- reference: PMID:11703332
reference_title: "Clinical, biochemical and molecular findings in a series of families with hereditary hyperferritinaemia-cataract syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "We followed an HHCS newborn in whom well-defined lens opacities were not detectable either at birth or at 1 year."
explanation: The observation behind the caveat that the cataract is not invariably congenital despite the disease name.
- reference: PMID:41281144
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome: A Pediatric Case Without Congenital Cataract."
supports: SUPPORT
directness: INDIRECT
evidence_source: HUMAN_CLINICAL
snippet: "reported on a pediatric case of HHCS that did not present with cataracts; this case, unlike our case, involved exclusively maternal relatives of the male proband harboring a different variant (A37C) in FTL"
explanation: >-
A 2025 report recording an earlier paediatric case that presented with no
cataract at all, which is the strongest form of the not-invariably-congenital
caveat: not merely delayed, but absent at presentation. Marked INDIRECT
because the sentence is this paper's summary of a different paper's case
(Serra et al. 2011), not an observation of its own; the primary report is
not in the reference cache, so the inference step is the one from a
secondary account to the case it describes.
- reference: PMID:41281144
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome: A Pediatric Case Without Congenital Cataract."
supports: SUPPORT
directness: INDIRECT
evidence_source: HUMAN_CLINICAL
snippet: "At diagnosis, the child had no visual deficits or lenticular opacities but remains under regular follow-up for early cataract detection"
explanation: >-
The tabulated detail of that earlier case (Serra et al. 2011, as summarised
in this report). Quoted from the 2025 paper because that is the cached
source; the primary report is not in the reference cache. Marked INDIRECT
for that reason - the quote is a secondary account of the case, not the
case report itself.
- reference: PMID:41281144
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome: A Pediatric Case Without Congenital Cataract."
supports: SUPPORT
evidence_source: OTHER
snippet: "While cataracts are the cardinal and well-documented ocular manifestation of HHCS, the correlation between genotype and the variability of the ocular phenotype, including factors such as age of onset and severity of cataracts, remains poorly understood"
explanation: >-
States that the determinants of ocular-phenotype variability are unknown,
which is why this entry records the range of presentations rather than a
genotype-based expectation. Graded OTHER rather than HUMAN_CLINICAL even
though the publication is a case report: this particular sentence is the
paper's review-style framing of the literature, not an observation of its
own patient, which is how the same kind of sentence is graded on the
venesection-harm node above (PMID:30678075).
sequelae:
- target: Visual Impairment
causal_link_type: DIRECT
- category: Ophthalmologic
name: Nuclear Cataract
description: >-
The opacity characteristically involves the embryonic and fetal lens nucleus,
the part of the lens laid down earliest, which is consistent with an
accumulation that begins in utero or in early life. Nuclear involvement was
part of the original 1995 clinical definition and remains the most consistent
morphology across series.
frequency: FREQUENT
phenotype_term:
preferred_term: Nuclear cataract
term:
id: HP:0100018
label: Nuclear cataract
evidence:
- reference: PMID:7492760
reference_title: "Molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome: a mutation in the iron-responsive element of ferritin L-subunit gene (the \"Verona mutation\")."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "clinically characterized by the combination of elevated serum ferritin and congenital bilateral nuclear cataract, both cotransmitted as an autosomal dominant trait"
explanation: Nuclear morphology is part of the founding clinical definition of the syndrome.
- reference: PMID:36768886
reference_title: Hereditary Hyperferritinemia.
supports: SUPPORT
evidence_source: OTHER
snippet: "Apart from hyperferritinemia, the only consistent abnormality in affected patients is a nuclear cataract, which appears in infancy or before the age of 50 years"
explanation: A recent review calls nuclear cataract the one consistent abnormality, which is the basis for recording it separately from the general cataract phenotype.
- category: Ophthalmologic
name: Pulverulent Lens Opacities
description: >-
The slit-lamp appearance is distinctive enough that experienced examiners have
argued it should raise the diagnosis on its own. The opacities are fine,
dust-like (pulverulent) or breadcrumb-like punctate flecks and small
crystalline aggregates distributed axially and peripherally; larger series
also describe a radial, sunflower-like arrangement in older lenses.
frequency: FREQUENT
diagnostic: true
phenotype_term:
preferred_term: Pulverulent, breadcrumb-like punctate lens opacities
term:
id: HP:0010693
label: Pulverulent cataract
notes: >-
Lachlan and colleagues describe the morphology in their seven British kindreds
as "sunflower" cataract, and HPO has a Sunflower cataract term (HP:6000642).
It is deliberately not bound here: HPO defines that term as an anterior
subcapsular copper deposit "almost only seen in Wilson disease", which is a
different lesion in a different lens layer that merely shares a floral
metaphor. Binding it would assert a Wilson-disease finding in an iron
disorder. Pulverulent cataract, defined in HPO as punctate dust-like
opacities of the fetal nucleus, matches the described lesion.
evidence:
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The cataract develops due to L-ferritin deposits in the lens and its pulverulent aspect is pathognomonic."
explanation: States both the pulverulent morphology and its diagnostic weight, which is why this phenotype is flagged diagnostic.
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The primary characteristics are the appearance of axial and peripheral white flecks and small crystalline aggregates."
explanation: Describes the axial and peripheral flecks and crystalline aggregates recorded in this phenotype's description.
- reference: PMID:15280904
reference_title: Clinical features and molecular analysis of seven British kindreds with hereditary hyperferritinaemia cataract syndrome.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "All the probands developed characteristic 'sunflower' morphology cataracts in childhood (median age at diagnosis 5 years), but had no other phenotypic features."
explanation: Source of the radial sunflower-like description and of the median age at diagnosis of five years; see this phenotype's notes for why the HPO Sunflower cataract term is not used.
- category: Ophthalmologic
name: Visual Impairment
description: >-
Reduced vision from the lens opacity is the only symptom the syndrome causes.
Severity ranges from an incidental slit-lamp finding to vision requiring
extraction, and dense opacity present during the visual-development window
carries the usual risk of deprivation amblyopia.
frequency: FREQUENT
phenotype_term:
preferred_term: Visual impairment
term:
id: HP:0000505
label: Visual impairment
evidence:
- reference: PMID:11703332
reference_title: "Clinical, biochemical and molecular findings in a series of families with hereditary hyperferritinaemia-cataract syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "No relevant symptoms other than visual impairment were found to be associated with the syndrome."
explanation: A 62-patient series establishing visual impairment as the only symptom, which supports both the phenotype and the negative claim about the rest of the body.
- category: Laboratory
name: Persistent Hyperferritinemia
description: >-
Lifelong elevation of serum ferritin, present from early life and usually
found incidentally. Reported values in affected adults commonly run from a few
hundred to well over 2,000 microgram/L; the original Verona family ranged from
950 to 2,259 microgram/L, and the seven British kindreds had a median of 1,420
microgram/L against a laboratory range of 15-360. Levels vary between and
within families sharing an allele, and are not a reliable index of cataract
severity in an individual.
frequency: OBLIGATE
diagnostic: true
phenotype_term:
preferred_term: Increased circulating ferritin concentration
term:
id: HP:0003281
label: Increased circulating ferritin concentration
temporality: CHRONIC
evidence:
- reference: PMID:7492760
reference_title: "Molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome: a mutation in the iron-responsive element of ferritin L-subunit gene (the \"Verona mutation\")."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "In affected subjects, hyperferritinemia (ranging from 950 to 2,259 micrograms/L) is typically not related to iron overload."
explanation: Gives the observed concentration range in the founding family and states that it is not iron-related.
- reference: PMID:15280904
reference_title: Clinical features and molecular analysis of seven British kindreds with hereditary hyperferritinaemia cataract syndrome.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "All the probands received diagnoses of HHCS after the incidental discovery of increased serum L-ferritin concentration (median 1420 microg/l; normal range 15-360 microg/l), in most cases during investigation or screening for anaemia."
explanation: Supplies the median value and the local reference interval quoted in this description, and documents the incidental route to diagnosis.
- category: Hematologic
name: Iron Deficiency Anemia
description: >-
Not a manifestation of the disorder but of its mistreatment. Patients
venesected for a presumed haemochromatosis are drained of a normal iron store
and become iron deficient and microcytic, while the ferritin they were being
treated for does not move.
frequency: OCCASIONAL
phenotype_term:
preferred_term: Iron deficiency anemia following inappropriate venesection
term:
id: HP:0001891
label: Iron deficiency anemia
evidence:
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "These patients had been initially misdiagnosed with hereditary haemochromatosis, although no iron overload had been found in liver biopsies and they developed iron-deficiency anaemia after repeated venesections."
explanation: Records iron-deficiency anaemia as an observed consequence of venesection in misdiagnosed HHCS patients.
- reference: PMID:34064225
reference_title: "Hereditary Hyperferritinemia Cataract Syndrome: Ferritin L Gene and Physiopathology behind the Disease-Report of New Cases."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The proband and his daughter were treated as hereditary hemochromatosis with phlebotomies until they developed microcytic anemia."
explanation: A named instance of the same harm, and the source of the microcytic descriptor used in this phenotype's description.
biochemical:
- name: Serum ferritin
presence: Increased
context: >-
The defining analyte and the reason nearly every patient is found. The value
is generated by translation, not by iron, so it does not respond to iron
removal and cannot be used to titrate any therapy. In HHCS it has also lost
its ordinary meaning in the other direction, and will not fall to signal a
genuine iron deficiency.
biomarker_term:
preferred_term: serum L-ferritin
term:
id: NCIT:C224202
label: Serum Ferritin
readouts:
- target: Serum Hyperferritinemia Uncoupled from Body Iron Stores
relationship: READOUT_OF
direction: POSITIVE
endpoint_context: DIAGNOSTIC
interpretation: >-
Reports the circulating pool of constitutively synthesised L-ferritin. High
in every affected individual and unresponsive to iron manipulation.
evidence:
- reference: PMID:9226182
reference_title: "Hereditary hyperferritinemia-cataract syndrome: relationship between phenotypes and specific mutations in the iron-responsive element of ferritin light-chain mRNA."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "By using monoclonal antibodies specific for the H and L ferritin subunits, serum ferritin was found to be essentially L type in both normal and affected individuals."
explanation: Establishes that the analyte measured in serum is the L-subunit species that this pathophysiology node overproduces.
reference_ranges:
- loinc_term:
id: LOINC:2276-4
label: Ferritin [Mass/volume] in Serum or Plasma
lower_bound: 12.0
upper_bound: 300.0
unit: ug/L
population: adult males
evidence:
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Normal serum ferritin levels are ranging from 12 to 300 µg/L for males and from 12 to 150 µg/L for females"
explanation: The reference interval this study measured its HHCS family against, quoted for the male stratum.
notes: >-
Serum ferritin reference intervals are strongly assay- and
laboratory-dependent; a British series using a different assay quotes
15-360 microgram/L. Treat any single interval as indicative.
- loinc_term:
id: LOINC:2276-4
label: Ferritin [Mass/volume] in Serum or Plasma
lower_bound: 12.0
upper_bound: 150.0
unit: ug/L
population: adult females
evidence:
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Normal serum ferritin levels are ranging from 12 to 300 µg/L for males and from 12 to 150 µg/L for females"
explanation: The same source interval, quoted for the female stratum.
evidence:
- reference: PMID:41769540
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome Misdiagnosed as Iron Overload: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Serum ferritin was markedly elevated at 790 µg/L (reference range 23-333 µg/L)."
explanation: A worked example of the analyte and its local reference interval in a molecularly confirmed patient.
- name: Transferrin saturation
presence: Normal
context: >-
The single most useful discriminating measurement, and a normal result is the
finding that should stop a haemochromatosis work-up. Transferrin saturation
indexes iron in transit, which HHCS does not disturb, whereas ferritin has
been detached from iron entirely. Serum iron and total iron-binding capacity
behave the same way.
biomarker_term:
preferred_term: transferrin saturation
term:
id: NCIT:C98792
label: Transferrin Saturation Measurement
readouts:
- target: Serum Hyperferritinemia Uncoupled from Body Iron Stores
relationship: READOUT_OF
endpoint_context: DIAGNOSTIC
interpretation: >-
Normal in HHCS. No direction is recorded because the informative result is
the absence of a change, and the direction enum has no value for that. Its normality alongside a very high ferritin is what
establishes that the ferritin is not reporting body iron.
evidence:
- reference: PMID:26849797
reference_title: "Hyperferritinemia-cataract syndrome: Long-term ophthalmic observations in an Italian family."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Serum ferritin concentrations were considerably elevated while serum iron, transferrin and transferrin saturation levels were within the normal range in each sibling."
explanation: Reports the dissociated pattern measured in all three affected siblings of one family.
reference_ranges:
- loinc_term:
id: LOINC:2502-3
label: Iron saturation [Mass Fraction] in Serum or Plasma
lower_bound: 15.0
upper_bound: 50.0
unit: '%'
population: adults
evidence:
- reference: PMID:21936912
reference_title: "Hyperferritinemia without iron overload in patients with bilateral cataracts: a case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "the serum transferrin saturation of 23.3% was within our laboratory reference interval (normal range 15-50%)"
explanation: Gives the laboratory reference interval against which the normal saturation in an HHCS patient was judged.
evidence:
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Diagnosis relies on the detection of persistently elevated serum ferritin with otherwise normal iron parameters (serum iron, transferrin saturation, and total iron-binding capacity), absence of inflammation or liver disease, and the presence of early-onset bilateral cataracts."
explanation: Places normal transferrin saturation, serum iron and TIBC at the centre of the diagnostic pattern.
genetic:
- name: FTL
gene_term:
preferred_term: FTL
term:
id: hgnc:3999
label: FTL
relationship_type: CAUSATIVE
presence: Present
frequency: The only gene in which variants are known to cause HHCS
notes: >-
Pathogenic HHCS variants lie exclusively in the FTL 5' UTR IRE and are
therefore invisible to a coding-only panel or to a conventional exome
filtering strategy - a recurring reason for diagnostic delay. Two numbering
conventions coexist in the literature: a historical one counting from the
transcription start site and naming the allele after the city of first report
(Paris-1 +40A>G, Verona-1 +41G>C), and HGVS c.- numbering from the ATG. FTL
is allelic for four other phenotypes, including neuroferritinopathy; see
`differential_diagnoses` and `kb/disorders/neuroferritinopathy.yaml`.
evidence:
- reference: PMID:34064225
reference_title: "Hereditary Hyperferritinemia Cataract Syndrome: Ferritin L Gene and Physiopathology behind the Disease-Report of New Cases."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "At least 47 mutations have been described in FTL gene as causative of HHCS, including 36 single mutations, 9 deletions, and 2 insertion-deletions"
explanation: States the size and composition of the allelic spectrum in the single causative gene.
- reference: PMID:34064225
reference_title: "Hereditary Hyperferritinemia Cataract Syndrome: Ferritin L Gene and Physiopathology behind the Disease-Report of New Cases."
supports: SUPPORT
evidence_source: OTHER
snippet: "c.-160A>G is the same as the +40A>G Paris-1 mutation"
explanation: Documents the equivalence of the two numbering conventions described in these notes.
- reference: PMID:33221470
reference_title: "Hereditary hyperferritinemia-cataract syndrome in three Czech families: molecular genetic testing and clinical implications."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Noncoding regions are often omitted from diagnostic gene panels, thus evading detection."
explanation: Supports the diagnostic-ascertainment point made in these notes.
variants:
- name: FTL c.-168G>C
description: >-
A recurrent allele affecting the conserved three-nucleotide bulge of the
FTL IRE, reported in Czech and Italian families among others.
gene:
preferred_term: FTL
term:
id: hgnc:3999
label: FTL
clinical_significance: PATHOGENIC
regulatory_category: GOE
evidence:
- reference: PMID:29426274
reference_title: "FTL c.-168G>C Mutation in Hereditary Hyperferritinemia Cataract Syndrome: A New Italian Family."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "This report documents a second Italian family, with a c.-168G>C mutation that is located in the highly conserved 3-nucleotide bulge structure of the FTL in the 5' untranslated region."
explanation: Names the variant and localises it within the IRE bulge.
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Genetic testing confirmed a heterozygous FTL c.-168G>C variant."
explanation: An independent family carrying the same allele, supporting its recurrence.
- name: FTL c.-167C>T
description: >-
Documented arising de novo, with paternity confirmed - the allele that shows
a negative family history cannot exclude the diagnosis.
gene:
preferred_term: FTL
term:
id: hgnc:3999
label: FTL
clinical_significance: PATHOGENIC
regulatory_category: GOE
evidence:
- reference: PMID:33221470
reference_title: "Hereditary hyperferritinemia-cataract syndrome in three Czech families: molecular genetic testing and clinical implications."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "but c.-167C>T occurred de novo (confirmed by paternity testing)"
explanation: Establishes de novo occurrence of this specific allele with paternity testing.
- name: FTL c.-151A>G (Ghent +49A>G)
description: >-
An upper-stem allele just above the cytosine bulge. Predicted to disrupt
base pairing at the base of the upper stem and, through that, the apical
loop and the bulge. Notable as the best-quantified example of a partial
lesion: it reduces IRP1 affinity more than five-fold without abolishing
binding, and still causes disease. Reported homozygous in a consanguineous
family, where the homozygote was the most severely affected member.
gene:
preferred_term: FTL
term:
id: hgnc:3999
label: FTL
clinical_significance: PATHOGENIC
regulatory_category: GOE
evidence:
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "The direct as well as competitive EMSA experiments show that +49A > G reduces, but not completely abolishes, the binding with recombinant IRP1."
explanation: The functional result behind the partial-lesion description of this allele.
- name: FTL IRE six-nucleotide deletion (Italian family)
description: >-
An example of the deletion class of HHCS alleles, in a repeat-containing
stretch such that the deletion can be written four equivalent ways. Cited
here to make the point that the allelic spectrum is not confined to
substitutions.
gene:
preferred_term: FTL
term:
id: hgnc:3999
label: FTL
clinical_significance: PATHOGENIC
regulatory_category: GOE
evidence:
- reference: PMID:11849230
reference_title: A novel deletion of the L-ferritin iron-responsive element responsible for severe hereditary hyperferritinaemia-cataract syndrome.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "We report a novel six-nucleotide deletion identified in an Italian family presenting with elevated serum ferritin and early onset bilateral cataract."
explanation: Documents a deletion allele and the phenotype it produced.
- reference: PMID:11849230
reference_title: A novel deletion of the L-ferritin iron-responsive element responsible for severe hereditary hyperferritinaemia-cataract syndrome.
supports: SUPPORT
evidence_source: COMPUTATIONAL
snippet: "Structural modelling predicted an IRE stem modification that is expected to markedly reduce the binding to iron-regulatory proteins."
explanation: The structural prediction linking this deletion to the shared mechanism; graded COMPUTATIONAL because it is an in-silico model rather than a binding assay.
diagnosis:
- name: Isolated hyperferritinaemia with normal iron indices
description: >-
The screening step. A persistently high serum ferritin with a normal serum
iron, a normal transferrin saturation and a normal total iron-binding
capacity, in a patient with no inflammation, no liver disease, no malignancy
and no heavy alcohol intake, is the laboratory signature. Recognising it is
what makes liver biopsy unnecessary.
presence: Present
evidence:
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "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."
explanation: States the laboratory triad and the exclusions, and names the next step.
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Invasive diagnostics such as liver biopsy are not indicated."
explanation: Supports the claim that recognising the pattern removes the indication for biopsy.
- name: Slit-lamp examination of the lens
description: >-
Ophthalmological confirmation. Slit-lamp and retro-illumination examination
shows the characteristic fine punctate and crystalline opacities, which are
detectable in family members long before they are symptomatic and can
therefore be used to establish the diagnosis in a proband and to screen
relatives.
presence: Present
evidence:
- reference: PMID:16496261
reference_title: "Hereditary hyperferritinemia cataract syndrome: ocular, genetic, and biochemical findings."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Lens opacities were detectable in young members of the family, and morphology of cataracts was consistent with previous reports."
explanation: Shows that slit-lamp examination detects the opacities early and that the morphology is reproducible across families.
- reference: PMID:16496261
reference_title: "Hereditary hyperferritinemia cataract syndrome: ocular, genetic, and biochemical findings."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "The morphology of cataracts in HHCS seems to be similar in all cases."
explanation: Supports the consistency of the appearance across affected individuals, which is what makes the examination diagnostically useful.
- name: Sequencing of the FTL 5' untranslated region
description: >-
Definitive confirmation. Targeted Sanger sequencing of the FTL 5' UTR and
exon 1 identifies the causal variant. The test has to be requested
specifically: the region is non-coding, so it is frequently absent from
cataract and iron-disorder panels and poorly covered by exome filtering.
presence: Present
evidence:
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Definitive diagnosis is established by identifying a pathogenic variant in the FTL IRE region through molecular testing"
explanation: Names molecular testing of the FTL IRE as the definitive diagnostic step.
- reference: PMID:28746593
reference_title: Ferritin light chain gene mutations in two Brazilian families with hereditary hyperferritinemia-cataract syndrome.
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "For the definitive diagnosis, the affected patients, their parents and siblings were submitted to Sanger sequencing of the 5'UTR region for detection of the ferritin light gene mutation."
explanation: Describes the specific assay used, in probands and relatives, in a family study.
- name: Exclusion of parenchymal iron overload by MRI
description: >-
Where doubt remains, quantitative liver MRI answers the iron-overload question
non-invasively and replaces the liver biopsy that misdiagnosed patients have
historically undergone.
presence: Absent
evidence:
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Magnetic resonance imaging excluded systemic iron overload, while ophthalmological evaluation revealed bilateral cataracts."
explanation: A worked instance of MRI being used to exclude iron overload in a suspected HHCS case.
treatments:
- name: Cataract Extraction
description: >-
The only established phenotype-directed intervention, and in most patients the
only clinical consequence of the diagnosis. Standard lens extraction with
intraocular lens implantation is performed when the opacity materially impairs
vision; in a child with a dense cataract it is also the intervention that
prevents deprivation amblyopia. Surgery removes the opaque lens, not the
underlying derepression, so the serum ferritin is unchanged by it.
action_category: THERAPEUTIC
therapeutic_modality: SURGERY
treatment_term:
preferred_term: Cataract Surgery
term:
id: NCIT:C157809
label: Cataract Surgery
target_phenotypes:
- preferred_term: Bilateral early-onset cataract
term:
id: HP:0000519
label: Developmental cataract
target_mechanisms:
- target: Crystalline L-Ferritin Deposition and Lens Light Scattering
treatment_effect: BYPASSES
description: >-
Extraction removes the tissue carrying the deposits rather than acting on
the deposition process, which continues unchanged elsewhere.
evidence:
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Patients diagnosed with HHCS should be counselled regarding the relative harmlessness of this genetic disease, with early cataract surgery as the only clinical consequence."
explanation: Establishes cataract surgery as the sole clinical intervention the diagnosis leads to.
- reference: PMID:30678075
reference_title: "L-Ferritin: One Gene, Five Diseases; from Hereditary Hyperferritinemia to Hypoferritinemia-Report of New Cases."
supports: SUPPORT
evidence_source: OTHER
snippet: "Apart from the surgical removal of cataracts in HHCS, HHCS and L-ferritin deficiency have no specific therapy."
explanation: States explicitly that no therapy other than cataract removal exists, supporting the scope of this treatment entry.
- name: Avoidance of Venesection, Iron Chelation and Liver Biopsy
description: >-
Withholding iron-depletion therapy is a genuine intervention here rather than
the absence of one, because the default management of a high ferritin is to
remove iron and that default is harmful in HHCS. Phlebotomy cannot lower a
translationally driven ferritin and instead induces iron deficiency; chelation
is worse, having caused life-threatening hyperammonaemia in a child treated
with deferasirox on a mistaken diagnosis; and liver biopsy, once routine in
this work-up, is not indicated once the iron indices are normal. The correct
action after diagnosis is to explain to the patient, and to record for future
clinicians, that the ferritin is genetically driven and is not evidence of
iron overload. Iron deficiency arising independently must still be treated on
its own evidence, since the ferritin will not report it.
action_category: THERAPEUTIC
treatment_term:
preferred_term: Withholding of iron-depletion therapy
term:
id: NCIT:C49236
label: Therapeutic Procedure
evidence:
- reference: PMID:21936912
reference_title: "Hyperferritinemia without iron overload in patients with bilateral cataracts: a case series."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Liver biopsy and phlebotomy should be avoided in this disorder."
explanation: A direct clinical recommendation to withhold both interventions, which is what this entry records.
- reference: PMID:41769540
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome Misdiagnosed as Iron Overload: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Ferritin overproduction in HHCS is independent of iron availability; therefore, iron removal does not correct hyperferritinemia and may instead induce iron deficiency anemia and related clinical symptoms."
explanation: Gives the mechanistic reason the intervention is both futile and harmful.
- reference: PMID:33221470
reference_title: "Hereditary hyperferritinemia-cataract syndrome in three Czech families: molecular genetic testing and clinical implications."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Careful clinical evaluations and targeted genetic screening are important for avoiding potentially harmful treatments."
explanation: The study's own conclusion, drawn from the phlebotomy and deferasirox harms it reports.
- reference: PMID:36768886
reference_title: Hereditary Hyperferritinemia.
supports: SUPPORT
evidence_source: OTHER
snippet: "In patients with HHCS, serum ferritin is no longer a reliable indicator of iron stores in both iron deficiency and iron overload, which is something to keep in mind."
explanation: Supports the closing caveat that a genuine iron deficiency must be diagnosed by other means.
- name: Genetic Counselling and Cascade Family Screening
description: >-
Once a proband is confirmed, first-degree relatives are offered targeted FTL
testing, serum ferritin measurement and slit-lamp examination. This identifies
affected relatives before they present, allows their cataracts to be followed
and removed at the right time, and - the more important benefit in practice -
prevents each of them from being separately worked up and venesected for a
presumed haemochromatosis.
action_category: COUNSELING_INFORMATIONAL
treatment_term:
preferred_term: Genetic Counseling
term:
id: NCIT:C15240
label: Genetic Counseling
evidence:
- reference: PMID:41769540
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome Misdiagnosed as Iron Overload: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Genetic counseling and cascade testing enable the identification of asymptomatic carriers, facilitate anticipatory guidance regarding cataract development, and prevent misinterpretation of ferritin elevations in affected relatives."
explanation: States all three benefits of cascade testing recorded in this entry.
- reference: PMID:16496261
reference_title: "Hereditary hyperferritinemia cataract syndrome: ocular, genetic, and biochemical findings."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Serum ferritin levels can be effectively used to screen for this condition in suspected families."
explanation: Supports serum ferritin as the cheap first-line screening test within a known family.
differential_diagnoses:
- name: Hereditary haemochromatosis
description: >-
The diagnosis HHCS is most often mistaken for, and the reason the mistake
matters: haemochromatosis is treated by venesection, which in HHCS is futile
and harmful. The discriminator is transferrin saturation, which is raised in
haemochromatosis and normal in HHCS, together with the absence of parenchymal
iron on imaging. Note that an incidental HFE H63D heterozygote is common in
European populations and has been found alongside a confirmed FTL IRE variant
without affecting the ferritin or hepcidin, so an HFE result does not settle
the question either way.
distinguishing_features:
- Transferrin saturation is raised in hereditary haemochromatosis and normal in HHCS.
- Parenchymal iron is increased in haemochromatosis and absent on liver MRI or biopsy in HHCS.
- Venesection lowers ferritin in haemochromatosis; in HHCS it produces iron deficiency while the ferritin stays high.
- Early bilateral cataract, and a family history of it, belong to HHCS and are not features of haemochromatosis.
evidence:
- reference: PMID:41769540
reference_title: "Hereditary Hyperferritinemia-Cataract Syndrome Misdiagnosed as Iron Overload: A Case Report."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Because elevated serum ferritin is commonly interpreted as a surrogate marker of iron overload, HHCS is frequently misdiagnosed as hereditary hemochromatosis or secondary iron overload, leading to unnecessary investigations and potentially harmful therapeutic phlebotomies."
explanation: States the confusion, its cause and its consequence.
- reference: PMID:41300832
reference_title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Additional screening for common HFE variants revealed heterozygous H63D in several family members, with no impact on ferritin or hepcidin levels."
explanation: Supports the caveat that an incidental HFE variant coexists without explaining the ferritin.
- name: Neuroferritinopathy
description: >-
The other end of the FTL allelic series and the entity this one must not be
merged with. Neuroferritinopathy is caused by coding-region FTL variants,
mostly C-terminal, produces a progressive movement disorder with basal-ganglia
iron accumulation, and runs with a low or normal serum ferritin - the opposite
biochemical direction. Curated separately as
`kb/disorders/neuroferritinopathy.yaml`.
disease_term:
preferred_term: neuroferritinopathy
term:
id: MONDO:0011638
label: neuroferritinopathy
distinguishing_features:
- The HHCS lesion is non-coding, in the FTL 5' UTR IRE; the neuroferritinopathy lesion is in the FTL coding sequence.
- Serum ferritin is high in HHCS and low or normal in neuroferritinopathy.
- HHCS has no neurological manifestations; neuroferritinopathy is defined by chorea, dystonia and parkinsonism.
- HHCS causes no tissue iron accumulation; neuroferritinopathy accumulates iron in the basal ganglia.
evidence:
- reference: PMID:30678075
reference_title: "L-Ferritin: One Gene, Five Diseases; from Hereditary Hyperferritinemia to Hypoferritinemia-Report of New Cases."
supports: SUPPORT
evidence_source: OTHER
snippet: "Defects in the FTL gene lead to abnormally high levels of serum ferritin (hyperferritinemia) in HHCS and benign hyperferritinemia, while low levels (hypoferritinemia) are present in neuroferritinopathy and in autosomal dominant and recessive L-ferritin deficiency."
explanation: States the opposite biochemical directions of the two FTL disorders, which is the primary discriminator.
- reference: PMID:30678075
reference_title: "L-Ferritin: One Gene, Five Diseases; from Hereditary Hyperferritinemia to Hypoferritinemia-Report of New Cases."
supports: SUPPORT
evidence_source: OTHER
snippet: "So far, there have been ten reported mutations causing this condition, mostly located at the C-terminal region of the FLT gene"
explanation: Locates the neuroferritinopathy alleles in the coding C-terminus, against the 5' UTR location of the HHCS alleles. The source's "FLT" is its own typographical error for FTL and is quoted as printed.
- name: Benign hyperferritinaemia
description: >-
A third FTL disorder: dominant hyperferritinaemia without cataract and without
iron overload, caused by missense changes in the first exon rather than in the
IRE, with more than 90% of the circulating ferritin glycosylated. It is the
differential for an isolated high ferritin in a family where slit-lamp
examination is clean. Because HHCS cataract can be late, a young relative with
a normal lens does not by itself distinguish the two.
distinguishing_features:
- The lesion is in FTL exon 1 and changes the protein, not the IRE.
- No cataract, at any age, in reported families.
- More than 90% of serum ferritin is glycosylated.
evidence:
- reference: PMID:36768886
reference_title: Hereditary Hyperferritinemia.
supports: SUPPORT
evidence_source: OTHER
snippet: "Benign hyperferritinemia is another rare dominant form of inherited hyperferritinemia not associated with iron overload or cataracts caused by mutations in FTL."
explanation: Defines the entity and its two distinguishing negatives.
- reference: PMID:36768886
reference_title: Hereditary Hyperferritinemia.
supports: SUPPORT
evidence_source: OTHER
snippet: "This ferritin is susceptible to glycosylation, and the degree of glycosylation of serum ferritin is always greater than 90%."
explanation: Supplies the biochemical discriminator recorded in the distinguishing features.
discussions:
- discussion_id: hhcs_lens_tissue_selectivity
kind: KNOWLEDGE_GAP
prompt: >-
Why is the lens the only tissue damaged by an L-ferritin excess that is
present in every cell of the body?
attaches_to:
- pathophysiology#Lens Fibre Cell L-Ferritin Accumulation
- pathophysiology#Crystalline L-Ferritin Deposition and Lens Light Scattering
rationale: >-
The derepression is constitutive and ubiquitous - lymphoblastoid cells from
patients carry up to twenty-fold excess L-ferritin - yet the only organ that
is injured is the lens. Three partial explanations are on the table and none
has been tested against the others. FTL transcription is measurably higher in
the lens than in neighbouring ocular tissue, so the same fractional
derepression yields a larger absolute burden there. Lens fibre cells are
post-mitotic, organelle-free and cannot dilute or degrade an accumulating
protein, so a small chronic surplus integrates over decades. And Levi and
colleagues proposed that L-ferritin specifically perturbs the solubility
equilibrium of the crystallins or the lens antioxidant defences, which would
make the injury a property of the lens proteome rather than of dose or
kinetics. Distinguishing these matters practically, because only the third
predicts that the crystallins are involved, and the entry's conformance to
`cataract_lens_opacification` is deliberately declared around, not through,
that module's crystallin-aggregation node for exactly this reason.
evidence:
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: OTHER
snippet: "Although ferritin accumulates in all cell types of HHCS patients, it turns out to be toxic only in the crystallin-containing lens fiber cells."
explanation: States the puzzle this gap is about - ubiquitous accumulation, single-organ injury.
- reference: PMID:29269865
reference_title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
supports: SUPPORT
evidence_source: OTHER
snippet: "Interestingly, it has been demonstrated that endogenous FTL transcription is significantly higher in the lens compared to other eye tissues, which is likely to contribute to the pathogenic levels of FTL deposits found in HHCS lenses"
explanation: The dose-based candidate explanation, offered by its own source as a likely contribution rather than a demonstrated cause.
- reference: PMID:9596665
reference_title: Analysis of ferritins in lymphoblastoid cell lines and in the lens of subjects with hereditary hyperferritinemia-cataract syndrome.
supports: SUPPORT
evidence_source: IN_VITRO
snippet: "L-chain accumulation occurs also in the lens, where it may induce cataract formation by altering the delicate equilibrium between other water-soluble proteins (ie, crystallins) and/or the antioxidant properties."
explanation: The competing proteome-based explanation, likewise stated by its authors as a possibility.
- discussion_id: hhcs_genotype_severity_relationship
kind: KNOWLEDGE_GAP
prompt: >-
Does IRE position predict phenotype severity well enough to be clinically
useful, given how much variation there is between people carrying the same
allele?
attaches_to:
- pathophysiology#Loss of Iron-Regulatory Protein Binding to the FTL IRE
rationale: >-
Two well-supported statements sit uneasily together. At the level of the
allele, position in the IRE tracks severity: variants in the conserved apical
hexanucleotide or the cytosine bulge give the highest ferritin values and the
earliest, densest cataracts, while lower-stem variants can be nearly
asymptomatic, and thermodynamic analysis correlates clinical severity with the
extent of IRE-IRP disturbance. At the level of the patient, that signal
largely disappears: the age at cataract diagnosis among sixteen carriers of a
single allele spanned 6 to 40 years, ferritin values within one allele spanned
700 to 2,412 microgram/L, and the largest clinical series found no clear
relationship between genotype and clinical severity at all. Whether the
residual variance is modifier genes, environmental exposure of the lens, or
simply measurement noise in a small and heavily ascertained corpus is not
known, and until it is, an IRE position cannot be used to counsel an
individual family about when their child will need surgery.
evidence:
- reference: PMID:20511138
reference_title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Cazzola and co-workers showed that mutations in the highly conserved hexanucleotide region (eg at position 40 or 41) caused a severe cataract, while mutations around the bulge with unpaired cytidine (eg position 32) caused mild cataract."
explanation: The allele-level position-severity relationship that makes the gap worth stating.
- reference: PMID:15280904
reference_title: Clinical features and molecular analysis of seven British kindreds with hereditary hyperferritinaemia cataract syndrome.
supports: REFUTE
evidence_source: HUMAN_CLINICAL
snippet: "The severity of the clinical phenotype of HHCS was variable both within and between kindreds and showed no clear relationship to FTL genotype."
explanation: The largest clinical series found no usable genotype-phenotype relationship, which is the observation that contradicts the allele-level claim above and is why this is recorded as an open question rather than a settled one.
- reference: PMID:11703332
reference_title: "Clinical, biochemical and molecular findings in a series of families with hereditary hyperferritinaemia-cataract syndrome."
supports: SUPPORT
evidence_source: HUMAN_CLINICAL
snippet: "Similarly, serum ferritin levels varied substantially also within subjects sharing the same mutation (i.e. range for the A40G: 700-2412 microg/l)."
explanation: Quantifies the within-allele spread in ferritin quoted in the rationale.
notes: >-
Entity verification. MONDO:0010952 was resolved against the OLS MONDO adapter
before this entry was written and returns the label bound here, "hereditary
hyperferritinemia with congenital cataracts". The causal gene recorded in the
curation stub, hgnc:3999 FTL, was confirmed against the committed HGNC term
cache. Both deep-research reports agree on OMIM 600886, which matches the MONDO
record, and `just preflight-dr` returned PASS for the falcon report.
Why the name is slightly wrong, and why it is kept. The MONDO label says
"congenital cataracts", but the cataract is not reliably congenital: Girelli and
colleagues followed a variant-carrying newborn who had no detectable lens
opacity at birth or at one year, several later reports describe presentation in
adolescence or adulthood, a 2025 paediatric report is titled for its case
presenting without congenital cataract, and that report tabulates an earlier
paediatric case (Serra et al. 2011) in whom there were no lenticular opacities
at all at diagnosis. The two are different claims and were previously conflated
here: the 2025 case is "without congenital cataract", not "without cataract". The entry keeps the MONDO name for its `name` and
`disease_term` because that is the ontology anchor, and records the more
accurate "early-onset" framing in the phenotype descriptions.
Ontology decisions worth recording. Two bindings were considered and rejected.
HP:6000642 Sunflower cataract matches the word used by the largest British
series but not the lesion: HPO defines it as an anterior subcapsular copper
deposit seen almost only in Wilson disease, so it was not bound - see the notes
on the Pulverulent Lens Opacities phenotype. `functional_impact_category` was
left unasserted on the pathophysiology `genetic_context`, because every value in
that enum describes the activity of a gene product and this variant class leaves
the product untouched; the variant-level claim is carried by
`regulatory_category: GOE` on the `genetic.variants` entries instead. That
choice is itself imperfect and is flagged here: the enum names GOE
"gain of ectopic expression" and explicitly includes repressor-site disruption
as a route to it, which fits, but the derepression in HHCS is regulatory and
iron-independent rather than spatially ectopic. GOE is the only
gain-of-expression value available and no better one exists today.
Sources not used. PMID:15183095 (Hejtmancik and Kantorow, molecular genetics of
age-related cataract) contains a good HHCS mechanism paragraph, but only in its
full text; the cached record is abstract-only and holds nothing about HHCS, so
it was fetched, read and dropped rather than cited from a passage the cache
cannot verify. Its cache file has been removed accordingly - a committed cache
for a reference nothing cites is an orphan. The falcon report cites Van de
Sompele et al. 2017 by a DOI (10.1007/s00439-017-1835-3) that its own
reference validation could not resolve;
the same study is cited here as PMID:29269865, which resolves and whose cached
full text contains every quoted passage. ORPHA:163 was not cited because
generating an Orphanet cache entry requires a bulk rebuild that was out of scope
for this session.
Related entries. `kb/disorders/neuroferritinopathy.yaml` is the coding-region
FTL disorder and is listed in `differential_diagnoses`; the two share a gene and
nothing else mechanistically. `kb/disorders/IRIDA_Syndrome.yaml` and
`kb/disorders/aceruloplasminemia.yaml` are the other inherited iron-handling
entries in this knowledge base.
references:
- reference: PMID:7492760
title: "Molecular basis for the recently described hereditary hyperferritinemia-cataract syndrome: a mutation in the iron-responsive element of ferritin L-subunit gene (the \"Verona mutation\")."
- reference: PMID:7493028
title: Mutation in the iron responsive element of the L ferritin mRNA in a family with dominant hyperferritinaemia and cataract.
- reference: PMID:9226182
title: "Hereditary hyperferritinemia-cataract syndrome: relationship between phenotypes and specific mutations in the iron-responsive element of ferritin light-chain mRNA."
- reference: PMID:9596665
title: Analysis of ferritins in lymphoblastoid cell lines and in the lens of subjects with hereditary hyperferritinemia-cataract syndrome.
- reference: PMID:10828006
title: "Translational pathophysiology: a novel molecular mechanism of human disease."
- reference: PMID:10873976
title: The lens in hereditary hyperferritinaemia cataract syndrome contains crystalline deposits of L-ferritin.
- reference: PMID:11703332
title: "Clinical, biochemical and molecular findings in a series of families with hereditary hyperferritinaemia-cataract syndrome."
- reference: PMID:11849230
title: A novel deletion of the L-ferritin iron-responsive element responsible for severe hereditary hyperferritinaemia-cataract syndrome.
- reference: PMID:15280904
title: Clinical features and molecular analysis of seven British kindreds with hereditary hyperferritinaemia cataract syndrome.
- reference: PMID:16496261
title: "Hereditary hyperferritinemia cataract syndrome: ocular, genetic, and biochemical findings."
- reference: PMID:20511138
title: "Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder."
- reference: PMID:21936912
title: "Hyperferritinemia without iron overload in patients with bilateral cataracts: a case series."
- reference: PMID:26849797
title: "Hyperferritinemia-cataract syndrome: Long-term ophthalmic observations in an Italian family."
- reference: PMID:28746593
title: Ferritin light chain gene mutations in two Brazilian families with hereditary hyperferritinemia-cataract syndrome.
- reference: PMID:29269865
title: 'Functional characterization of a novel non-coding mutation "Ghent +49A > G" in the iron-responsive element of L-ferritin causing hereditary hyperferritinaemia-cataract syndrome.'
- reference: PMID:29426274
title: "FTL c.-168G>C Mutation in Hereditary Hyperferritinemia Cataract Syndrome: A New Italian Family."
- reference: PMID:30678075
title: "L-Ferritin: One Gene, Five Diseases; from Hereditary Hyperferritinemia to Hypoferritinemia-Report of New Cases."
- reference: PMID:33221470
title: "Hereditary hyperferritinemia-cataract syndrome in three Czech families: molecular genetic testing and clinical implications."
- reference: PMID:34064225
title: "Hereditary Hyperferritinemia Cataract Syndrome: Ferritin L Gene and Physiopathology behind the Disease-Report of New Cases."
- reference: PMID:36768886
title: Hereditary Hyperferritinemia.
- reference: PMID:41300832
title: "Clinical and Molecular Clues to Diagnosing Hereditary Hyperferritinemia-Cataract Syndrome: Case Report and Literature Review."
- reference: PMID:41769540
title: "Hereditary Hyperferritinemia-Cataract Syndrome Misdiagnosed as Iron Overload: A Case Report."
Deep research results are used as seeds for research; they do not undergo the same validation as the main records and may contain errors. How we use deep research.
Record notes
Entity verification. MONDO:0010952 was resolved against the OLS MONDO adapter before this entry was written and returns the label bound here, "hereditary hyperferritinemia with congenital cataracts". The causal gene recorded in the curation stub, hgnc:3999 FTL, was confirmed against the committed HGNC term cache. Both deep-research reports agree on OMIM 600886, which matches the MONDO record, and `just preflight-dr` returned PASS for the falcon report. Why the name is slightly wrong, and why it is kept. The MONDO label says "congenital cataracts", but the cataract is not reliably congenital: Girelli and colleagues followed a variant-carrying newborn who had no detectable lens opacity at birth or at one year, several later reports describe presentation in adolescence or adulthood, a 2025 paediatric report is titled for its case presenting without congenital cataract, and that report tabulates an earlier paediatric case (Serra et al. 2011) in whom there were no lenticular opacities at all at diagnosis. The two are different claims and were previously conflated here: the 2025 case is "without congenital cataract", not "without cataract". The entry keeps the MONDO name for its `name` and `disease_term` because that is the ontology anchor, and records the more accurate "early-onset" framing in the phenotype descriptions. Ontology decisions worth recording. Two bindings were considered and rejected. HP:6000642 Sunflower cataract matches the word used by the largest British series but not the lesion: HPO defines it as an anterior subcapsular copper deposit seen almost only in Wilson disease, so it was not bound - see the notes on the Pulverulent Lens Opacities phenotype. `functional_impact_category` was left unasserted on the pathophysiology `genetic_context`, because every value in that enum describes the activity of a gene product and this variant class leaves the product untouched; the variant-level claim is carried by `regulatory_category: GOE` on the `genetic.variants` entries instead. That choice is itself imperfect and is flagged here: the enum names GOE "gain of ectopic expression" and explicitly includes repressor-site disruption as a route to it, which fits, but the derepression in HHCS is regulatory and iron-independent rather than spatially ectopic. GOE is the only gain-of-expression value available and no better one exists today. Sources not used. PMID:15183095 (Hejtmancik and Kantorow, molecular genetics of age-related cataract) contains a good HHCS mechanism paragraph, but only in its full text; the cached record is abstract-only and holds nothing about HHCS, so it was fetched, read and dropped rather than cited from a passage the cache cannot verify. Its cache file has been removed accordingly - a committed cache for a reference nothing cites is an orphan. The falcon report cites Van de Sompele et al. 2017 by a DOI (10.1007/s00439-017-1835-3) that its own reference validation could not resolve; the same study is cited here as PMID:29269865, which resolves and whose cached full text contains every quoted passage. ORPHA:163 was not cited because generating an Orphanet cache entry requires a bulk rebuild that was out of scope for this session. Related entries. `kb/disorders/neuroferritinopathy.yaml` is the coding-region FTL disorder and is listed in `differential_diagnoses`; the two share a gene and nothing else mechanistically. `kb/disorders/IRIDA_Syndrome.yaml` and `kb/disorders/aceruloplasminemia.yaml` are the other inherited iron-handling entries in this knowledge base.
Create: Hereditary Hyperferritinemia with Congenital Cataracts · 2026-09-05T18:23:34Z · View source
Created kb/disorders/Hereditary_Hyperferritinemia_With_Congenital_Cataracts.yaml (MONDO:0010952, FTL / hgnc:3999, autosomal dominant) de novo, and deleted the corresponding curation stub. DEEP RESEARCH THAT ACTUALLY RAN. Two providers, both successfully, no fallback. (1) asta - research/Hereditary_Hyperferritinemia_With_Congenital_Cataracts-deep-research-asta.md, retrieval-only, 16 papers / 20 snippets, reference_validation 30/30 resolved, 0 unresolved, 0 off-topic, term_validation found no CURIEs to check. `just preflight-dr` returned WARN on this report: rival gene HFE at 26% of FTL mentions. That WARN was inspected and dismissed on reading - the HFE mentions are the misdiagnosis-as-haemochromatosis discussion that is the clinical core of this disease, and the CRYGD/BFSP2/MIP mentions come from five generic congenital-cataract papers Asta retrieved as topical noise (items 4, 7, 8, 11, 14). None of those five is cited in the entry. (2) falcon (Edison) - research/...-deep-research-falcon.md, 615 s, 59 citations, one artifact. `just preflight-dr` returned PASS (FTL 29 mentions, OMIM 600886 in both the report and MONDO). Its reference_validation flagged one unresolved identifier, DOI:10.1007/s00439-017-1835-3, given for Van de Sompele et al. 2017; it is not cited. Its term_validation flagged MONDO:0010952 as "mislabelled" against the reported label "if available", which is a template placeholder leaking into the report rather than a real term error - the CURIE and its label were confirmed independently against ols:mondo. GENEREVIEWS. There is no GeneReviews chapter for this disease. Searched PubMed two ways - `hyperferritinemia cataract GeneReviews[All Fields]` and `(hyperferritinemia[TI] AND cataract[TI]) AND GeneReviews[BOOK]` - both returned zero records. Per the skill, absence needs no workaround; the phenotype baseline was built instead from the two largest clinical series (PMID:15280904, 49 individuals across seven British kindreds; PMID:11703332, 62 patients in 14 families) plus the 2010 worldwide mutation-and-phenotype review (PMID:20511138) and the 2023/2025 reviews (PMID:36768886, PMID:41300832). MECHANISM MODEL AND WHY. An eight-node causal chain, MOLECULAR -> ORGANISM, with a branch: FTL Iron-Responsive Element Disruption -> Loss of Iron-Regulatory Protein Binding to the FTL IRE -> Constitutive Derepression of L-Ferritin Translation -> L-Ferritin Overproduction and Intracellular Accumulation, which then branches to (a) Serum Hyperferritinemia Uncoupled from Body Iron Stores and (b) Lens Fibre Cell L-Ferritin Accumulation -> Crystalline L-Ferritin Deposition and Lens Light Scattering. Every edge except two carries its own cited evidence separate from the node evidence. JUDGEMENT CALLS A REVIEWER SHOULD SEE. 1. The iatrogenic arm is modelled inside the pathograph, not left as prose. Serum Hyperferritinemia -> Iatrogenic Iron Depletion from Misdirected Venesection and Chelation is typed INDIRECT_KNOWN_INTERMEDIATES with the intermediate recorded explicitly as "Misattribution of isolated hyperferritinaemia to hereditary haemochromatosis", because the intervening step is interpretive rather than biological. That is a deliberate choice and it is argued in the node description. The harm is the clinically dominant fact about this disease (PMID:7492760, PMID:20511138, PMID:33221470, PMID:41769540, PMID:30678075) and it also drives a treatment entry (Avoidance of Venesection, Iron Chelation and Liver Biopsy) and the hereditary-haemochromatosis differential. 2. Modifier grading. GO:0006413 translational initiation is tagged GAIN_OF_FUNCTION and GO:0045947 negative regulation of translational initiation LOSS_OF_FUNCTION, rather than the default INCREASED/DECREASED, because the change is qualitative in exactly the sense CLAUDE.md reserves those values for: PMID:9596665 shows L-ferritin in patient cells is "not affected by iron supplementation or chelation", i.e. the process has left its regulatory circuit rather than merely running faster. By contrast GO:0030350 iron-responsive element binding is tagged DECREASED, which is quantitative and correct - PMID:29269865 measures a 5-fold affinity loss that does not abolish binding. 3. functional_impact_category is deliberately NOT set on the pathophysiology genetic_context, and the reason is written into the block. Every value in FunctionalImpactEnum describes the activity of a gene product; an IRE variant leaves the L-ferritin protein untouched and changes only how much is made. The variant-level claim is carried by regulatory_category: GOE on the four genetic.variants entries instead. GOE is itself imperfect - the enum titles it "gain of ectopic expression" and HHCS derepression is regulatory, not spatially ectopic - but its description explicitly lists repressor-site disruption as a route, it is the only gain-of-expression value available, and the mismatch is flagged in the entry notes rather than hidden. 4. Module conformance is declared around, not through, the cataract module. Two nodes conform to cataract_lens_opacification: Lens Fibre Cell L-Ferritin Accumulation -> "#Lens Homeostasis Insult", and Crystalline L-Ferritin Deposition and Lens Light Scattering -> "#Loss of Lens Refractive Transparency and Light Scattering". The module's two intermediate nodes are crystallin-centred (loss of crystallin solubility, then crystallin aggregate deposition) and HHCS largely bypasses them: the deposits are crystals of an overproduced non-crystallin protein. The caveat is recorded in that node's notes, and whether the crystallins are involved at all is the untested Levi hypothesis (PMID:9596665), captured as a knowledge-gap discussion. 5. HP:6000642 Sunflower cataract was considered and REJECTED even though PMID:15280904 calls the HHCS morphology "sunflower". HPO defines that term as an anterior subcapsular copper deposit "almost only seen in Wilson disease" - a different lesion in a different lens layer sharing a floral metaphor. HP:0010693 Pulverulent cataract (punctate dust-like opacities of the fetal nucleus) was bound instead. Reasoning is recorded on the phenotype and in the entry notes. 6. The MONDO label says "congenital cataracts" and the cataract is often not congenital (PMID:11703332 followed a variant-carrying newborn with no opacity at birth or one year). The MONDO name is kept for name/disease_term as the ontology anchor; the phenotype descriptions carry the accurate "early-onset" framing. Explained in notes. 7. Two reference_ranges are curated on serum ferritin (sex-stratified, PMID:29269865) and one on transferrin saturation (PMID:21936912), each with a citable evidence item rather than a free-text source, against LOINC:2276-4 and LOINC:2502-3. Both LOINC codes were looked up in the NLM Clinical Table Search Service, not written from memory. No interpretation_bands: HHCS has no graded severity tiers for ferritin, and the entry states explicitly that the value does not index cataract severity. REFERENCES CONSIDERED AND REJECTED. - PMID:15183095 (Hejtmancik and Kantorow, molecular genetics of age-related cataract) was fetched because Asta surfaced a good HHCS mechanism paragraph from it. That paragraph is full text only; the cached record is abstract-only and contains nothing about HHCS. Dropped rather than cited from text the cache cannot verify. - NCIT:C74736 was very nearly bound as "Transferrin Saturation" from memory. It is in fact "C-peptide Measurement". Caught by checking cache/ncit/terms.csv before validating; corrected to NCIT:C98792 Transferrin Saturation Measurement. Recorded here because the near-miss is exactly the failure mode the term contract exists for. - GO:0070288 ferritin complex was first used as the serum-ferritin biomarker_term; BiomarkerTerm is NCIT-only, so it was replaced with NCIT:C224202 Serum Ferritin. - ORPHA:163 is the Orphanet identifier for this disease but `just fetch-reference ORPHA:163` has no source; generating it needs a bulk Orphadata rebuild, which was out of scope for this session, so no ORPHA evidence is cited. - The five generic congenital-cataract papers in the Asta report (CRYGD, Cat-Map, WES cohorts) were read and not used: they are about cataract genetics in general, not this disease. NOT DONE. - No `datasets:` block. FTL dataset search is a textbook Named Entity Confusion trap - the gene's transcriptomic literature is dominated by neurodegeneration and by ferritin as an inflammatory marker, and this ultra-rare non-coding disorder has no omics corpus of its own (the falcon report independently reports finding no single-cell, spatial, proteomic, metabolomic or multi-omics HHCS study). Rather than attach accessions that resolve but are not about this disease, the block is omitted. This is the main reason global compliance is 94.5% and not higher. - No `animal_models:`, `experimental_models:` or `computational_models:`. No animal model of HHCS has been published; the falcon report reaches the same conclusion. The in-vitro work that exists (patient lymphoblastoid lines, recombinant IRP1 EMSA) is curated as evidence on the mechanism nodes rather than invented as model records. - No `clinical_trials:`. The only registered study the falcon report found (NCT05659017, "Candidate Gene for Hyperferritinemia") is observational with unknown status and is not an HHCS treatment trial; not curated. - classifications.harrisons_chapter and .icimd_category carry notes but no evidence items, matching the convention in kb/disorders/Methylmalonic_Aciduria_cblA_Type.yaml and IRIDA_Syndrome.yaml. VALIDATION ACTUALLY RUN, ALL TO COMPLETION. - `just validate kb/disorders/Hereditary_Hyperferritinemia_With_Congenital_Cataracts.yaml` -> schema "No issues found"; terms "Validation passed"; references "All validations passed", snippets 95/95 verified. - `just validate-disorders <file>` (the batched CI gate) -> all three stages pass, 95/95 snippets. - `just count-verified-snippets <file>` -> 95/95 verified, 0 skipped. - `just check-entity-refs <file>` -> OK. - `just check-causal-targets <file>` -> OK, no new broken targets. - `just check-duplicate-keys <file>` -> OK. - `just check-enum-values <file>` -> OK. - `just check-qualifier-terms <file>` -> OK (the entry uses no `qualifiers` blocks). - `just compliance <file>` -> Global 94.5% (172/182), Weighted 95.0%. - Self-checks scripted against the cache for this file only, since the corresponding repo recipes are whole-KB and this checkout is shared with other in-flight curation: all 117 (reference, reference_title) pairs match the cached frontmatter title; no snippet is a paper title; no snippet under 40 characters; no quoted sentence carries two different evidence_source values; no snippet uses a folded scalar. Whole-KB recipes (`just qc`, `just validate-all`, `just check-reference-titles`, `just check-snippet-grading`) were deliberately not run - six other agents are curating in this same working tree and their in-flight files would dominate the output.
This report is retrieval-only and is generated directly from Asta results.
search_papers_by_relevance with snippet_search.Checked with linkml-reference-validator 0.2.1.
| Outcome | Count |
|---|---|
| References checked | 30 |
| Resolved | 30 |
| Unresolved (possible confabulation) | 0 |
| Unverifiable | 0 |
| References weighed for topical relevance | 30 |
| On topic | 16 |
| Off topic | 0 |
All extracted references resolved successfully.
No ontology term identifiers were found in this report.
Question: You are an expert researcher providing comprehensive, well-cited information.
Provide detailed information focusing on: 1. Key concepts and definitions with current understanding 2. Recent developments and latest research (prioritize 2023-2024 sources) 3. Current applications and real-world implementations 4. Expert opinions and analysis from authoritative sources 5. Relevant statistics and data from recent studies
Format as a comprehensive research report with proper citations. Include URLs and publication dates where available. Always prioritize recent, authoritative sources and provide specific citations for all major claims.
Please provide a comprehensive research report on Hereditary Hyperferritinemia with Congenital Cataracts covering all of the disease characteristics listed below. This report will be used to populate a disease knowledge base entry. Be thorough and cite primary literature (PMID preferred) for all claims.
For each section, suggested databases/resources are listed. These are the first places you should search for information on each topic.
Search first: OMIM, Orphanet, ICD-10/ICD-11, MeSH, PubMed
Search first: PubMed, Cochrane Library, UpToDate, clinical guidelines, ClinVar, ClinGen, GWAS Catalog, PheGenI, CTD, CDC, WHO, epidemiological databases
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Search first: CTD, PubMed, PheGenI, GxE databases
Search first: HPO (Human Phenotype Ontology), OMIM, Orphanet, PubMed, clinicaltrials.gov, MedDRA, SNOMED CT, DECIPHER, LOINC
For each phenotype, provide: - Phenotype type: symptoms, clinical signs, physical manifestations, behavioral changes, or laboratory abnormalities
For symptoms/signs: HPO, OMIM, Orphanet, PubMed For behavioral changes: HPO, DSM, RDoC (Research Domain Criteria), PubMed For laboratory abnormalities: LOINC, SNOMED CT, LabTests Online, PubMed - Phenotype characteristics: Search first: OMIM, Orphanet, HPO, PubMed - Age of symptom onset (neonatal, childhood, adult-onset, late-onset) - Symptom severity (mild, moderate, severe, variable) - Symptom progression (stable, progressive, episodic, fluctuating) - Frequency among affected individuals (percentage or qualitative) - Quality of life impact: Effects on daily functioning and well-being (per-phenotype when possible) Search first: EQ-5D database, SF-36, WHO QOL databases, PubMed - Suggest HPO (Human Phenotype Ontology) terms for each phenotype
Search first: OMIM, ClinVar, HGMD, Ensembl, NCBI Gene
Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
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Present this section as an ordered causal chain first, then the detail below. Open with a numbered sequence of mechanistic steps running from the initiating lesion (mutation, exposure, infection) to the clinical manifestation, one step per line, each naming what it causes next. State the causal verb explicitly ("leads to", "results in") and say where a step is inferred rather than demonstrated. Where the mechanism branches, show the branch. The categories below are a checklist of what to cover within those steps, not the organizing structure — a step may draw on several of them, and a category may contribute to several steps.
Search first: KEGG, Reactome, WikiPathways, PathBank, BioCyc
Search first: Gene Ontology (GO), Reactome, KEGG, PubMed
Search first: UniProt, PDB (Protein Data Bank), InterPro, Pfam, AlphaFold
Search first: KEGG, BioCyc, HMDB (Human Metabolome Database), BRENDA
Search first: ImmPort, Immunome Database, IEDB, Gene Ontology
Search first: PubMed, Gene Ontology, Reactome
Search first: BRENDA, UniProt, KEGG, OMIM, PubMed
Search first: ENCODE, Roadmap Epigenomics, MethBase, DiseaseMeth
For each mechanism, describe: - The causal chain from initial trigger to clinical manifestation - Which mechanisms are upstream vs downstream - What cell types and biological processes are involved - Suggest GO terms for biological processes and CL terms for cell types
Search first: Uberon, FMA (Foundational Model of Anatomy), OMIM, HPO, ICD-11, MeSH, SNOMED CT
Search first: Uberon, Human Protein Atlas, Cell Ontology, Human Cell Atlas, CellMarker, PanglaoDB
Search first: Gene Ontology (Cellular Component), UniProt, Human Protein Atlas
Search first: OMIM, Orphanet, HPO, PubMed
Search first: Disease registries, longitudinal cohort databases, natural history studies, PubMed, Orphanet, OMIM
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Search first: GTR (Genetic Testing Registry), GeneReviews, ClinGen
For each treatment, suggest NCIT (NCI Thesaurus) clinical-intervention terms where applicable.
Search first: CDC vaccine schedules, WHO immunization, FDA vaccine database
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Structure your response as a comprehensive narrative organized by the sections above. For each section, provide: - Factual content with specific details (numbers, percentages, gene names, variant nomenclature) - Ontology term suggestions (HPO, GO, CL, UBERON, CHEBI, NCIT, MONDO) where applicable - Evidence citations with PMIDs - Direct quotes from abstracts to support key claims - Clear indication when information is not available or not applicable for this disease
This report will be used to populate a disease knowledge base entry with: - Pathophysiology descriptions with causal chains - Gene/protein annotations (HGNC, GO terms) - Phenotype associations (HP terms) with frequencies - Cell type involvement (CL terms) - Anatomical locations (UBERON terms) - Chemical entities (CHEBI terms) - Treatment annotations (NCIT terms) - Evidence items with PMIDs and exact abstract quotes - Epidemiology, prognosis, diagnostic, and prevention information - Animal model descriptions with phenotype recapitulation details
Hereditary hyperferritinemia–cataract syndrome (HHCS), also called hereditary hyperferritinemia with congenital cataracts, is a rare Mendelian disorder caused by germline noncoding variants in the iron-responsive element (IRE) of FTL, the ferritin light-chain gene. These variants impair post-transcriptional repression of FTL, causing iron-independent overproduction of L-ferritin. The defining phenotype is persistent, often marked hyperferritinemia without systemic iron overload, together with bilateral, usually early-onset and slowly progressive nuclear cataracts containing L-ferritin-rich deposits. The major clinical hazard is not systemic disease but misdiagnosis as hemochromatosis, followed by unnecessary liver biopsy, phlebotomy, or iron chelation. Cataract surgery is the only established phenotype-directed intervention; there is no treatment indication for the ferritin elevation itself. (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, eris2023hereditaryhyperferritinemiacataractsyndrome pages 4-5, piperno2023hereditaryhyperferritinemia pages 10-12)
The most useful knowledge-base summary is:
| Knowledge-base field | Evidence-supported summary | Key sources |
|---|---|---|
| Disease / identifiers | Hereditary hyperferritinemia-cataract syndrome (HHCS; OMIM #600886) is a rare Mendelian disorder characterized by persistent hyperferritinemia unrelated to body iron stores and early-onset bilateral cataracts. | Piperno et al., 2023; Moravikova et al., 2020 (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, piperno2023hereditaryhyperferritinemia pages 10-12) |
| Causal gene / inheritance | FTL (ferritin light-chain gene); usually heterozygous autosomal-dominant inheritance. De novo disease and rare homozygous affected individuals have been documented. | Moravikova et al., 2020; Van de Sompele et al., 2017 (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, sompele2017functionalcharacterizationofa pages 2-3) |
| Molecular lesion | Pathogenic noncoding substitutions, deletions, and insertion-deletions affect the iron-responsive element (IRE) in the FTL 5′ untranslated region, especially its upper stem, conserved hexaloop, and cytosine bulge. A 2019 review catalogued 36 point mutations, nine deletions, and two insertion-deletions associated with HHCS. | Cadenas et al., 2019; Millonig et al., 2010 (millonig2010hyperferritinaemiacataractsyndromeworldwide pages 9-10, cadenas2019lferritinonegene pages 5-8) |
| Core mechanism | IRE disruption reduces binding of iron-regulatory proteins IRP1/IRP2 and releases normal iron-dependent translational repression, causing constitutive excess L-ferritin synthesis. Functional EMSA evidence showed reduced IRP1 affinity for the c.-151A>G IRE. L-ferritin-rich deposits/crystals in the lens diffract light and produce cataract; absence of systemic iron excess distinguishes HHCS from hemochromatosis. | Van de Sompele et al., 2017; Piperno et al., 2023 (piperno2023hereditaryhyperferritinemia pages 10-12, sompele2017functionalcharacterizationofa pages 8-9, sompele2017functionalcharacterizationofa pages 2-3) |
| Ferritin / iron laboratory pattern | Persistent, often marked serum hyperferritinemia with normal serum iron, transferrin saturation, and body-iron stores. Reported serum ferritin is commonly about 700–2,000 µg/L; one seven-kindred series recorded minima of 740–1,960 µg/L (median 1,420 µg/L). Ferritin may fluctuate but did not increase with age in that series. | Lachlan et al., 2004; Cosentino et al., 2016 (lachlan2004clinicalfeaturesand pages 1-2, cosentino2016hyperferritinemiacataractsyndromelongterm pages 1-6) |
| Ocular phenotype / onset | Bilateral, generally symmetrical nuclear cataracts can be congenital or recognized in infancy, childhood, or later adulthood. Typical findings include punctate white “breadcrumb-like,” crystalline, sunflower-like, or radial opacities. Cataracts are usually slowly progressive; visual severity and age at surgery vary within and among families. In one British series, median diagnosis was five years and median extraction age was 25 years (range 22–42). | Lachlan et al., 2004; Cosentino et al., 2016 (lachlan2004clinicalfeaturesand pages 3-4, lachlan2004clinicalfeaturesand pages 1-2, cosentino2016hyperferritinemiacataractsyndromelongterm pages 1-6) |
| Epidemiology | Worldwide distribution; approximate prevalence 1:200,000, but this is an estimate rather than a population-registry measurement. A 2018 report noted approximately 160 known families/cases. No established sex bias is supported. | Piperno et al., 2023; Ferro et al., 2018 (ferro2018ftlc.168g>cmutation pages 1-2, piperno2023hereditaryhyperferritinemia pages 10-12) |
| Diagnosis | Suspect HHCS when isolated familial hyperferritinemia coexists with early bilateral cataracts and normal transferrin saturation. Evaluate blood count, serum iron, transferrin/TIBC, transferrin saturation, liver enzymes, and inflammatory causes; slit-lamp examination can reveal characteristic opacities. Confirm by sequencing the FTL 5′UTR/IRE and test relatives. Liver biopsy is generally unnecessary when iron overload has been excluded. | Millonig et al., 2010; Moravikova et al., 2020 (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4) |
| Management | Hyperferritinemia itself requires no iron-removal treatment. Avoid phlebotomy and iron chelation unless independent iron overload is proven; misdiagnosis has caused iron-deficiency anemia and, in one report, life-threatening hyperammonemia during deferasirox therapy. Monitor vision and perform standard cataract extraction with intraocular-lens management when visual function warrants it. | Moravikova et al., 2020; Piperno et al., 2023 (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, eris2023hereditaryhyperferritinemiacataractsyndrome pages 4-5, piperno2023hereditaryhyperferritinemia pages 10-12) |
| Prognosis | Life-threatening systemic disease or shortened survival has not been demonstrated. Morbidity is predominantly visual and usually amenable to cataract surgery. Serum hyperferritinemia is lifelong but is not, by itself, evidence of organ iron injury. | Millonig et al., 2010; Piperno et al., 2023 (millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4, piperno2023hereditaryhyperferritinemia pages 10-12) |
| Evidence gaps | No robust incidence, sex-ratio, penetrance, quality-of-life, survival, or population carrier-frequency studies were identified. Genotype–phenotype prediction remains weak except that rare biallelic variants may be more severe. No HHCS-specific therapeutic trials, validated pharmacotherapy, gene/RNA therapy, direct disease animal model, or single-cell, spatial-transcriptomic, epigenomic, proteomic, metabolomic, or multi-omics study was found in the gathered evidence. | Cadenas et al., 2019; Shiels, 2024 (sompele2017functionalcharacterizationofa pages 8-9, cadenas2019lferritinonegene pages 5-8, shiels2024throughthecatmapa pages 20-21, shiels2024throughthecatmap pages 19-21) |
Table: Concise evidence table covering the defining clinical, molecular, diagnostic, management, and epidemiologic features of HHCS, together with major evidence gaps. Claims are restricted to the gathered literature and distinguish estimated figures from directly observed findings.
Evidence consists chiefly of multigeneration human families, small case series, biochemical studies of mutant IRE–IRP binding, and reviews. HHCS is so rare that registry-quality incidence, penetrance, survival, quality-of-life, and treatment-response data are unavailable. The most current disease-focused synthesis retrieved was Piperno et al., published January 2023; a June 2024 cataract-genetics review places FTL within the contemporary inherited-cataract landscape but adds no HHCS-specific therapy or model. (piperno2023hereditaryhyperferritinemia pages 10-12, shiels2024throughthecatmap pages 3-4, shiels2024throughthecatmap pages 19-21)
PMIDs were not present in the retrieved full-text metadata and therefore are not supplied speculatively. DOI links and publication dates are provided. Short quotations below are limited to wording verifiable in retrieved abstracts.
HHCS is an autosomal-dominant disorder characterized by persistent elevation of serum L-ferritin, normal body-iron stores and transferrin saturation, and bilateral congenital, juvenile, or presenile cataract. It should not be classified as hereditary hemochromatosis: the elevated ferritin reflects dysregulated ferritin synthesis rather than excess stored iron. (lachlan2004clinicalfeaturesand pages 1-2, millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4, piperno2023hereditaryhyperferritinemia pages 10-12)
A landmark review defines it as follows: “The hereditary hyperferritinaemia-cataract syndrome (HHCS) is characterised by an autosomal dominant cataract and high levels of serum ferritin without iron overload.” Millonig et al., April 2010. (millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4)
The report concerns aggregated disease-level literature and published patients/families, not individual EHR records.
The cause is a germline FTL 5′-UTR IRE variant—usually a heterozygous substitution, deletion, or insertion-deletion. The altered RNA stem-loop has reduced affinity for iron-regulatory proteins, releasing the normal iron-sensitive block on translation. (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, millonig2010hyperferritinaemiacataractsyndromeworldwide pages 9-10, cadenas2019lferritinonegene pages 5-8)
A 2019 catalog reported 36 point mutations, nine deletions, and two insertion-deletions associated with HHCS. Examples include c.-161C>T, c.-167C>T, c.-168G>C, c.-151A>G, and c.-164_-158del7. Nomenclature varies historically because variants were numbered relative to the IRE rather than consistently by HGVS; clinical reports should normalize against NM_000146.3 or the current MANE transcript. (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, sompele2017functionalcharacterizationofa pages 2-3, cadenas2019lferritinonegene pages 3-5, cadenas2019lferritinonegene pages 5-8)
No validated protective allele, modifier gene, diet, drug, or lifestyle intervention has been shown to prevent HHCS. Intrafamilial variability indicates that modifiers probably exist, but none is established. Ferritin level and cataract severity do not show a reliable one-to-one relationship. (lachlan2004clinicalfeaturesand pages 1-2, piperno2023hereditaryhyperferritinemia pages 10-12)
No disease-specific gene–environment interaction has been demonstrated. Inflammation, alcohol use, metabolic syndrome, malignancy, infection, and liver disease can independently raise ferritin and obscure the characteristic biochemical pattern, but they do not cause the inherited syndrome. Coexisting iron deficiency or true iron overload can occur independently and must be assessed on its own evidence. (eris2023hereditaryhyperferritinemiacataractsyndrome pages 4-5, millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4)
There is no infectious cause, toxin-associated cause, occupational risk, or zoonotic component.
| Phenotype | Type and course | Frequency/evidence | Suggested HPO term |
|---|---|---|---|
| Hyperferritinemia | Laboratory abnormality; usually lifelong, persistent but quantitatively fluctuating | Defining biochemical feature; commonly about 700–2,000 µg/L. Seven British kindreds had minimum recorded values 740–1,960 µg/L, median 1,420 µg/L | Hyperferritinemia (HP:0003281; verify current release) |
| Bilateral nuclear cataract | Clinical sign/structural ocular phenotype; congenital, infantile, childhood, or presenile; usually slowly progressive | Defining clinical manifestation, although timing and severity vary | Cataract (HP:0000518); Congenital cataract; Nuclear cataract |
| Punctate/crystalline lens opacities | Slit-lamp sign: breadcrumb-like, pulverulent, sunflower/radial, peripheral flecks or crystalline inclusions | Highly characteristic but morphology is not invariant | Lens opacity / cataract morphology terms |
| Reduced visual acuity | Functional consequence; ranges from mild to surgery-requiring | Four young members in one family had acuity below 20/40; many remain mildly affected for years | Reduced visual acuity (HP:0007663) |
| Normal transferrin saturation/body iron | Negative diagnostic feature | Typical and central to distinction from hemochromatosis | Use laboratory annotation rather than a disease HPO term |
(lachlan2004clinicalfeaturesand pages 3-4, lachlan2004clinicalfeaturesand pages 1-2, cosentino2016hyperferritinemiacataractsyndromelongterm pages 1-6, ferro2018ftlc.168g>cmutation pages 1-2)
In seven British kindreds, cataract was diagnosed at a median age of five years; most affected people eventually underwent extraction at a median age of 25 years (range 22–42). Infant lenses could show sparse posterior breadcrumb-like opacities, adolescent lenses sunflower-like radial opacities, and extracted lenses crystalline inclusions immunoreactive for L-ferritin. Severity varied substantially within and between families. (lachlan2004clinicalfeaturesand pages 3-4, lachlan2004clinicalfeaturesand pages 1-2)
Long-term observations in an Italian family found limited progression over approximately 18 years, supporting a generally slow adult course. Other families show progressive visual impairment requiring surgery, so “slowly progressive and variable” is more accurate than “stable.” (cosentino2016hyperferritinemiacataractsyndromelongterm pages 1-6, ferro2018ftlc.168g>cmutation pages 1-2)
No HHCS-specific EQ-5D, SF-36, PROMIS, utility, educational, or employment study was identified. The principal impact is visual: glare, blur, impaired reading/driving or school performance, and—if dense cataract obstructs vision during early childhood—risk of deprivation amblyopia. General congenital-cataract guidance emphasizes early optical rehabilitation in visually significant infantile disease. (shiels2024throughthecatmap pages 3-4, shiels2024throughthecatmapa pages 4-5)
No reproducible behavioral, neurologic, hepatic, endocrine, cardiac, or inflammatory syndrome belongs to classic HHCS. Neurologic manifestations should prompt assessment for other FTL allelic disorders, especially neuroferritinopathy, or a second diagnosis. (cadenas2019lferritinonegene pages 1-3, cadenas2019lferritinonegene pages 5-8)
Serum ferritin is largely L-ferritin-rich, relatively iron-poor material; in HHCS, constitutive synthesis yields excess L-rich ferritin, including H0-L24 homopolymers. (piperno2023hereditaryhyperferritinemia pages 10-12, cadenas2019lferritinonegene pages 1-3)
Pathogenic HHCS variants cluster in structurally critical portions of the IRE: the conserved CAGUGX hexaloop, upper stem, and cytosine bulge. They include single-nucleotide substitutions and short indels. Examples with human segregation evidence include:
The c.-151A>G functional study used RNA-structure prediction and EMSA. Mutant RNA retained IRP1 binding but showed a greater than fivefold impairment in apparent affinity relative to wild type, demonstrating that partial—not only complete—loss of repression can cause disease. (sompele2017functionalcharacterizationofa pages 8-9, sompele2017functionalcharacterizationof pages 8-9)
ClinVar classifications must be retrieved variant by variant and transcript-normalized. Many classic alleles have strong pathogenic evidence from segregation, characteristic phenotype, rarity, critical RNA location, and functional assays, but the report should not automatically label every IRE variant pathogenic.
Pathogenic alleles are expected to be extremely rare. Variant-specific gnomAD/TOPMed frequencies were not available in the retrieved evidence and must be queried using normalized genomic coordinates. No reliable carrier-frequency estimate exists.
No validated modifier gene, disease-associated methylation signature, histone/chromatin abnormality, large deletion, translocation, inversion, aneuploidy, or recurrent structural variant has been established. HHCS is ordinarily a small noncoding sequence disorder.
Environmental exposure, diet, smoking, exercise, alcohol, radiation, pollution, and infectious agents are not established contributors to HHCS initiation. These factors may cause other cataracts or alter serum ferritin independently and therefore complicate diagnosis. Iron intake does not correct or normalize the regulatory defect, and a high ferritin value alone is not a reason to restrict dietary iron. Conversely, documented iron deficiency should not be left untreated merely because serum ferritin is high in HHCS; iron status must be assessed using transferrin saturation, hemoglobin, red-cell indices, and the broader clinical context. (eris2023hereditaryhyperferritinemiacataractsyndrome pages 4-5, millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4)
This is primarily an IRE–IRP post-transcriptional iron-homeostasis disorder, not a canonical Wnt, MAPK, mTOR, PI3K–AKT, hepcidin–ferroportin, immune, or inflammatory disease. Upstream events are RNA structural change and impaired translational repression; downstream events are L-ferritin overexpression, aggregation/deposition, optical scattering, and cataract.
An additional 2019 mechanistic study identified human eIF3 as a distinct repressor of FTL translation and showed that some hyperferritinemia-associated 5′-UTR variants can disrupt eIF3-mediated repression. This broadens current understanding of FTL translational control, although the gathered evidence does not establish eIF3 disruption for every clinically pathogenic HHCS allele.
No HHCS-specific immune activation, apoptosis signature, mitochondrial defect, lipidopathy, or systemic oxidative-injury phenotype is established.
No HHCS-specific single-cell RNA-seq, spatial transcriptomics, comprehensive proteomics, metabolomics, lipidomics, epigenomics, multi-omics integration, organoid study, or CRISPR/RNAi screen was identified. Lens immunoreactivity for L-ferritin and IRE-binding assays are the principal molecular-level evidence. (lachlan2004clinicalfeaturesand pages 3-4, shiels2024throughthecatmapa pages 20-21, shiels2024throughthecatmap pages 19-21)
The directly affected organ is the eye, specifically the crystalline lens, usually bilaterally and relatively symmetrically. Opacities frequently involve the embryonic/fetal nucleus and may extend centrifugally into cortical regions. No secondary systemic organ damage is expected from classic HHCS itself. (lachlan2004clinicalfeaturesand pages 3-4, ferro2018ftlc.168g>cmutation pages 1-2)
Suggested terms:
At the subcellular level, the key lesion is excess cytosolic L-ferritin and formation of high-molecular-weight/crystalline deposits. A primary nuclear-genome mutation is present, but the pathogenic deposits are not a nuclear-organelle lesion.
Serum hyperferritinemia is constitutional and likely present from early life, although it is often discovered incidentally during anemia evaluation, pregnancy screening, or family testing. Cataracts can be congenital or first recognized in infancy, childhood, adolescence, or adulthood. The 2023 synthesis places reported presentation approximately between ages 1 and 45 years. (lachlan2004clinicalfeaturesand pages 1-2, piperno2023hereditaryhyperferritinemia pages 10-12)
There is no formal staging system. A useful clinical sequence is:
The disorder is lifelong, generally chronic, and slowly progressive rather than episodic or relapsing. Cataracts do not spontaneously remit. Surgery removes the opaque lens, whereas serum hyperferritinemia persists. Dense infantile cataract represents the critical period because delayed optical correction risks irreversible amblyopia; milder adult disease can be monitored according to function. (lachlan2004clinicalfeaturesand pages 3-4, cosentino2016hyperferritinemiacataractsyndromelongterm pages 1-6, shiels2024throughthecatmap pages 3-4)
HHCS is predominantly autosomal dominant. Penetrance of biochemical hyperferritinemia appears high in reported mutation-positive families, but ascertainment is strong and no unbiased numerical estimate is available. Cataract expressivity and age at recognition are variable. No genetic anticipation has been demonstrated. Germline mosaicism is theoretically possible but not established as a recurrent phenomenon. (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, lachlan2004clinicalfeaturesand pages 1-2)
The best available prevalence estimate is approximately 1 per 200,000, worldwide, but this is not based on population-wide screening. A 2018 report cited roughly 160 known families/cases, indicating substantial under-recognition is plausible. Incidence, carrier frequency, and sex ratio are unknown. (ferro2018ftlc.168g>cmutation pages 1-2, piperno2023hereditaryhyperferritinemia pages 10-12)
Affected families have been reported across Europe, Asia, and the Americas and among multiple ancestries. No established ethnic restriction exists. Recurrent alleles may reflect mutationally sensitive IRE positions rather than a single universal founder. Consanguinity is not generally relevant to this dominant disease, although it enabled homozygosity in the c.-151A>G family. (sompele2017functionalcharacterizationofa pages 2-3)
MRI-based liver iron assessment may be used when biochemical or clinical findings genuinely suggest coincident iron overload. Routine liver biopsy is inappropriate merely for high ferritin in a characteristic HHCS case. Extracted lenses can contain crystalline, immunoreactive L-ferritin inclusions, but lens biopsy is not a diagnostic requirement. (lachlan2004clinicalfeaturesand pages 3-4, millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4)
There are no universally adopted society diagnostic criteria. The combination of isolated hyperferritinemia, normal iron loading, typical bilateral cataract, dominant pedigree, and a pathogenic FTL IRE variant is diagnostic.
Life expectancy is expected to be normal, and no HHCS-specific mortality signal, organ-failure risk, five- or ten-year survival estimate, or disease-specific death rate has been demonstrated. The principal morbidity is visual impairment. Hyperferritinemia is lifelong but does not itself signify progressive hepatic, cardiac, pancreatic, or neurologic iron injury. (millonig2010hyperferritinaemiacataractsyndromeworldwide pages 3-4, piperno2023hereditaryhyperferritinemia pages 10-12)
Visual prognosis after appropriately timed standard cataract treatment is generally favorable, although pediatric outcome depends on cataract density, age at intervention, amblyopia prevention, refractive rehabilitation, and postoperative complications. Quantitative HHCS-specific surgical response rates are unavailable. Some operated adults later required Nd:YAG capsulotomy, a common treatment for posterior capsule opacification rather than recurrence of the native lens cataract. (ferro2018ftlc.168g>cmutation pages 1-2)
Adverse prognosis is more likely to reflect delayed cataract treatment or iatrogenic iron depletion from inappropriate venesection than intrinsic systemic HHCS. No validated molecular prognostic biomarker beyond the causal genotype has been established.
Suggested NCIT concepts include Cataract Surgery, Lens Extraction, Intraocular Lens Implantation, Phacoemulsification, Genetic Counseling, and Observation; identifiers should be mapped against the current NCIT release.
Misdiagnosed patients have undergone repeated venesection and developed iron-deficiency anemia. One patient received deferasirox and developed life-threatening acute hyperammonemia. These reports make avoidance of unindicated iron-removal therapy a central safety intervention. (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, eris2023hereditaryhyperferritinemiacataractsyndrome pages 4-5)
No validated pharmacotherapy, ferritin-lowering drug, genotype-guided medication, gene therapy, CRISPR therapy, antisense oligonucleotide, siRNA, cell therapy, immunotherapy, or HHCS-specific interventional trial was identified. NCT05659017 (“Candidate Gene for Hyperferritinemia”) was retrieved as an observational study planned for 100 participants with status listed as unknown; it is not evidence of an HHCS treatment.
Gene editing and pharmacologic anti-cataract approaches are being studied for other cataract genes, but none can currently be extrapolated as HHCS therapy. (shiels2024throughthecatmapa pages 20-21, shiels2024throughthecatmap pages 19-21)
The occurrence of a de novo or inherited pathogenic allele cannot currently be prevented through lifestyle change or vaccination. Reproductive options following identification of a familial variant include prenatal diagnosis and preimplantation genetic testing after nondirective counseling, subject to local law and family preferences.
No immunization, chemoprophylaxis, environmental intervention, or population newborn-screening program is indicated. Population carrier screening is not supported by current prevalence or outcome data.
FTL and the IRE–IRP regulatory system are evolutionarily conserved across mammals, but no naturally occurring companion-animal, livestock, or wildlife syndrome convincingly equivalent to human HHCS was identified. Consequently, no breed-specific VBO annotation, veterinary prevalence, transmission pattern, cross-species susceptibility, or zoonotic potential can be assigned. HHCS is genetic and noncommunicable.
For comparative annotation, Mus musculus (NCBI Taxonomy 10090), Danio rerio (7955), and other vertebrates possess ferritin/iron-regulatory orthologs useful for studying general iron biology, but that does not constitute natural HHCS.
The strongest disease-specific experimental model is in vitro RNA–protein analysis. Mutant and wild-type FTL IRE RNAs have been assessed by structure prediction and direct/competitive EMSA with recombinant IRP1. The c.-151A>G mutant retained binding but had markedly impaired affinity, providing functional support for pathogenicity. (sompele2017functionalcharacterizationofa pages 8-9, sompele2017functionalcharacterizationof pages 8-9, sompele2017functionalcharacterizationofa pages 2-3)
Human extracted-lens material showing crystalline, immunoreactive L-ferritin deposits provides ex vivo pathological validation. (lachlan2004clinicalfeaturesand pages 3-4)
No well-validated mouse, rat, rabbit, zebrafish, Drosophila, organoid, or patient-iPSC model reproducing the complete HHCS triad—pathogenic FTL IRE allele, serum hyperferritinemia without iron overload, and characteristic ferritin cataract—was identified in the gathered evidence. FTL coding-mutant mice used for neuroferritinopathy and CRISPR models of other cataract genes should not be mislabeled as HHCS models. (shiels2024throughthecatmapa pages 20-21, shiels2024throughthecatmapa pages 29-30, shiels2024throughthecatmap pages 19-21)
A useful future model would be an FTL-IRE knock-in animal or human lens organoid carrying a recurrent pathogenic allele, with quantitative IRP occupancy, ribosome profiling, ferritin composition, lens transparency, aggregate imaging, and rescue by allele-selective translational repression.
The expert consensus across these sources is that HHCS is usually medically benign outside the lens, highly recognizable when ferritin and cataract are considered together, and disproportionately harmful when mistaken for iron overload. The most effective “precision medicine” implementation today is therefore accurate molecular diagnosis, cascade assessment, avoidance of venesection/chelation, and individualized ophthalmic care. (moravikova2020hereditaryhyperferritinemiacataractsyndrome pages 1-7, eris2023hereditaryhyperferritinemiacataractsyndrome pages 4-5, piperno2023hereditaryhyperferritinemia pages 10-12)
References
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(millonig2010hyperferritinaemiacataractsyndromeworldwide pages 9-10): Gunda Millonig, Martina U Muckenthaler, and Sebastian Mueller. Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder. Human Genomics, 4:250-262, Apr 2010. URL: https://doi.org/10.1186/1479-7364-4-4-250, doi:10.1186/1479-7364-4-4-250. This article has 69 citations and is from a peer-reviewed journal.
(cadenas2019lferritinonegene pages 5-8): Beatriz Cadenas, Josep Fita-Torró, Mar Bermúdez-Cortés, Inés Hernandez-Rodriguez, José Luis Fuster, María Esther Llinares, Ana María Galera, Julia Lee Romero, Santiago Pérez-Montero, Cristian Tornador, and Mayka Sanchez. L-ferritin: one gene, five diseases; from hereditary hyperferritinemia to hypoferritinemia—report of new cases. Pharmaceuticals, 12:17, Jan 2019. URL: https://doi.org/10.3390/ph12010017, doi:10.3390/ph12010017. This article has 38 citations.
(sompele2017functionalcharacterizationofa pages 8-9): S Van de Sompele, L Pécheux, J Couso, and A Meunier. Functional characterization of a novel non-coding mutation “ghent+ 49a> g” in the iron-responsive element of l-ferritin causing hereditary hyperferritinaemia-cataract …. Unknown journal, 2017.
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(cadenas2019lferritinonegene pages 3-5): Beatriz Cadenas, Josep Fita-Torró, Mar Bermúdez-Cortés, Inés Hernandez-Rodriguez, José Luis Fuster, María Esther Llinares, Ana María Galera, Julia Lee Romero, Santiago Pérez-Montero, Cristian Tornador, and Mayka Sanchez. L-ferritin: one gene, five diseases; from hereditary hyperferritinemia to hypoferritinemia—report of new cases. Pharmaceuticals, 12:17, Jan 2019. URL: https://doi.org/10.3390/ph12010017, doi:10.3390/ph12010017. This article has 38 citations.
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Checked with linkml-reference-validator 0.2.1.
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| Resolved | 9 |
| Unresolved (possible confabulation) | 1 |
| Unverifiable | 0 |
| References weighed for topical relevance | 9 |
| On topic | 2 |
| Off topic | 0 |
These identifiers did not resolve to a record and may be fabricated. A lookup that failed for transport reasons is indistinguishable from one that failed because the record does not exist, so spot-check before acting on them:
DOI:10.1007/s00439-017-1835-3 (3 mentions) - Identifier did not resolve to a recordChecked with linkml-term-validator 0.4.5, through the ols: adapter.
| Outcome | Count |
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| Terms checked | 4 |
| Resolved | 4 |
| Unresolved (possible confabulation) | 0 |
| Obsolete | 0 |
| Unverifiable | 0 |
| Terms whose name was checked | 3 |
| Terms named correctly | 2 |
| Terms named as a different term | 1 |
These identifiers resolve, so nothing about them looks wrong, and the ontology calls them something unrelated to what the report calls them. That usually means the identifier is not the one the sentence needs:
MONDO:0010952 (2 mentions) - the report calls it "if available"; MONDO calls it hereditary hyperferritinemia with congenital cataracts