Encyclopedia
Ferritin light chain
- genes
1. Normal Function
The FTL gene provides instructions for making the ferritin light chain, which is one part (subunit) of a protein called ferritin. Ferritin is made up of 24 subunits formed into a hollow spherical molecule. The 24 subunits consist of varying numbers of the ferritin light chain and another subunit called the ferritin heavy chain, which is produced from another gene. The proportion of the two subunits varies in different tissues.
Ferritin stores and releases iron in cells. Each ferritin molecule can hold as many as 4,500 iron atoms inside its spherical structure. This storage capacity allows ferritin to regulate the amount of iron in cells and tissues. Iron is needed for the body to produce red blood cells.
2. Health Conditions Related to Genetic Changes
2.1 Hyperferritinemia-Cataract Syndrome
At least 31 mutations in the FTL gene have been identified in people with hyperferritinemia-cataract syndrome. Individuals affected by this disorder have an excess of ferritin in the blood (hyperferritinemia) and tissues of the body. A buildup of this protein begins early in life, leading to clouding of the lenses of the eyes (cataracts) in infancy.
The mutations that cause hyperferritinemia-cataract syndrome are found in a segment of the gene called the iron responsive element (IRE). The IRE normally can attach (bind) to a protein called the iron regulatory protein (IRP). When this binding occurs, the activity (expression) of the FTL gene is stopped to prevent too much ferritin light chain from being produced. This normally occurs when iron levels are low, because under those circumstances less ferritin is needed to store the iron. Mutations in the IRE segment of the FTL gene prevent it from binding with IRP, interfering with the mechanism by which ferritin production is matched to iron levels and resulting in excess ferritin being formed.
2.2 Neuroferritinopathy
At least four mutations in the FTL gene have been identified in people with neuroferritinopathy, a disorder in which iron gradually accumulates in the brain. These mutations all affect an area of the gene known as exon 4. The most common mutation detected in people with this disorder inserts the DNA building block (nucleotide) adenine between positions 460 and 461 in the gene sequence. Researchers believe that most families with this mutation descend from a common ancestor who lived in northwest England before 1800. Three other known mutations are each found in a single individual or family affected by neuroferritinopathy.
Mutations in the FTL gene that cause neuroferritinopathy are believed to reduce ferritin's ability to store iron, resulting in the release of excess iron in nerve cells (neurons) of the brain. The cells may respond by producing more ferritin in an attempt to handle the free iron. Excess iron and ferritin accumulate in the brain, particularly in certain regions that help to control movement (basal ganglia), resulting in the movement problems and other neurological changes seen in neuroferritinopathy.
3. Other Names for This Gene
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ferritin L subunit
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ferritin L-chain
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ferritin light polypeptide-like 3
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ferritin, light polypeptide
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FRIL_HUMAN
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L apoferritin
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MGC71996
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NBIA3
This entry is adapted from the peer-reviewed paper https://medlineplus.gov/genetics/gene/ftl
References
- Burn J, Chinnery PF. Neuroferritinopathy. Semin Pediatr Neurol. 2006Sep;13(3):176-81.
- Cazzola M. Role of ferritin and ferroportin genes in unexplainedhyperferritinaemia. Best Pract Res Clin Haematol. 2005 Jun;18(2):251-63. Review.
- Craig JE, Clark JB, McLeod JL, Kirkland MA, Grant G, Elder JE, Toohey MG,Kowal L, Savoia HF, Chen C, Roberts S, Wirth MG, Mackey DA. Hereditaryhyperferritinemia-cataract syndrome: prevalence, lens morphology, spectrum ofmutations, and clinical presentations. Arch Ophthalmol. 2003 Dec;121(12):1753-61.
- Crompton DE, Chinnery PF, Fey C, Curtis AR, Morris CM, Kierstan J, Burt A,Young F, Coulthard A, Curtis A, Ince PG, Bates D, Jackson MJ, Burn J.Neuroferritinopathy: a window on the role of iron in neurodegeneration. BloodCells Mol Dis. 2002 Nov-Dec;29(3):522-31.
- Curtis AR, Fey C, Morris CM, Bindoff LA, Ince PG, Chinnery PF, Coulthard A,Jackson MJ, Jackson AP, McHale DP, Hay D, Barker WA, Markham AF, Bates D, Curtis A, Burn J. Mutation in the gene encoding ferritin light polypeptide causesdominant adult-onset basal ganglia disease. Nat Genet. 2001 Aug;28(4):350-4.
- Koorts AM, Viljoen M. Ferritin and ferritin isoforms I: Structure-functionrelationships, synthesis, degradation and secretion. Arch Physiol Biochem. 2007Feb;113(1):30-54. Review.
- Levi S, Cozzi A, Arosio P. Neuroferritinopathy: a neurodegenerative disorderassociated with L-ferritin mutation. Best Pract Res Clin Haematol. 2005Jun;18(2):265-76. Review.
- Madsen E, Gitlin JD. Copper and iron disorders of the brain. Annu RevNeurosci. 2007;30:317-37. Review.
- Millonig G, Muckenthaler MU, Mueller S. Hyperferritinaemia-cataract syndrome: worldwide mutations and phenotype of an increasingly diagnosed genetic disorder. Hum Genomics. 2010 Apr;4(4):250-62. Review.
- Vidal R, Ghetti B, Takao M, Brefel-Courbon C, Uro-Coste E, Glazier BS, SianiV, Benson MD, Calvas P, Miravalle L, Rascol O, Delisle MB. Intracellular ferritinaccumulation in neural and extraneural tissue characterizes a neurodegenerativedisease associated with a mutation in the ferritin light polypeptide gene. JNeuropathol Exp Neurol. 2004 Apr;63(4):363-80.
