The FAM126A gene provides instructions for making a protein called hyccin, which is active (expressed) throughout the nervous system. Researchers believe that hyccin is involved in the formation of myelin, which is the covering that protects nerves and promotes the efficient transmission of nerve impulses. Hyccin is also active in the lens of the eye, the heart, and the kidneys; however, the protein's function in these tissues is unclear.
Health Conditions Related to Genetic Changes
Hypomyelination and congenital cataract
At least four mutations in the FAM126A gene have been found to cause hypomyelination and congenital cataract. Most mutations delete a large portion of the gene or create a premature stop signal in the instructions for making hyccin. These mutations prevent the production of any functional protein. One FAM126A gene mutation allows some protein to be produced. This mutation replaces the protein building block (amino acid) leucine with the amino acid proline at position 53 in the hyccin protein (written as Leu53Pro or L53P). People with the Leu53Pro mutation tend to have milder symptoms than those with mutations that prevent the production of any protein.
Any disruption in the production of hyccin impairs its role in the formation of myelin, leading to neurological problems such as intellectual disability and walking difficulties. It is unclear how a lack of hyccin causes a clouding of the lens (cataract) in both eyes that is typically present from birth in affected individuals. The neurological problems and cataracts are the characteristic features seen in people with hypomyelination and congenital cataract.More About This Health Condition
Other Names for This Gene
- family with sequence similarity 126, member A
Additional Information & Resources
Tests Listed in the Genetic Testing Registry
Scientific Articles on PubMed
Catalog of Genes and Diseases from OMIM
- Biancheri R, Zara F, Bruno C, Rossi A, Bordo L, Gazzerro E, Sotgia F, Pedemonte M, Scapolan S, Bado M, Uziel G, Bugiani M, Lamba LD, Costa V, Schenone A, Rozemuller AJ, Tortori-Donati P, Lisanti MP, van der Knaap MS, Minetti C. Phenotypic characterization of hypomyelination and congenital cataract. Ann Neurol. 2007 Aug;62(2):121-7. Citation on PubMed
- Rossi A, Biancheri R, Zara F, Bruno C, Uziel G, van der Knaap MS, Minetti C, Tortori-Donati P. Hypomyelination and congenital cataract: neuroimaging features of a novel inherited white matter disorder. AJNR Am J Neuroradiol. 2008 Feb;29(2):301-5. Epub 2007 Nov 1. Citation on PubMed
- Ugur SA, Tolun A. A deletion in DRCTNNB1A associated with hypomyelination and juvenile onset cataract. Eur J Hum Genet. 2008 Feb;16(2):261-4. Epub 2007 Oct 10. Citation on PubMed
- Zara F, Biancheri R, Bruno C, Bordo L, Assereto S, Gazzerro E, Sotgia F, Wang XB, Gianotti S, Stringara S, Pedemonte M, Uziel G, Rossi A, Schenone A, Tortori-Donati P, van der Knaap MS, Lisanti MP, Minetti C. Deficiency of hyccin, a newly identified membrane protein, causes hypomyelination and congenital cataract. Nat Genet. 2006 Oct;38(10):1111-3. Epub 2006 Sep 3. Citation on PubMed