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Tyrosine Degradation and Melanin Synthesis

Albinism is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect in any one of a number of proteins involved in the production of melanin. Certain forms of albinism are known to be due to mutations in tyrosine metabolism. In oculocutaneous albinism (OCA), pigment is lacking in the eyes, skin and hair. In ocular albinism, only the eyes lack pigment. Patients with albinism experience varying degrees of vision loss associated with foveal hypoplasia, nystagmus, photophobia and/or glare sensitivity, refractive errors, and abnormal decussation of ganglion cell axons at the optic chiasm. Current treatment options for vision problems caused by albinism are limited to correction of refractive errors and amblyopia, low vision aids, and (in some cases) extraocular muscle surgery.

Technology: Nitisinone is an FDA-approved drug used in the treatment of tyrosinemia, type 1. The drug blocks the normal degradation pathway of tyrosine thus allowing greater circulating plasma levels of tyrosine. NEI investigators have identified that administration of Nitisinone to subjects (e.g., mice or humans) with certain forms of albinism, can result in increased circulating tyrosine levels, an increase in tyrosinase activity, and, subsequently, increased pigmentation.

Competitive Advantage: Nitisinone is an FDA-approved drug used in the treatment of tyrosinemia, type 1 and hence for its use in a second indication, will have abbreviated regulatory timeline. 

Nitisinone_chart

Left: Number of pigmented melanosomes in 10 equally magnified, representative fields of ocular tissues of vehicle- and nitisinonetreated Tyrc-h/c-h mice. Right: Coat color and iris pigmentation in Tyrc-h/c-h pups after prenatal treatment with nitisinone. Nitisinone improves eye and skin pigmentation defects in a mouse model of oculocutaneous albinism Brooks BP et al. J Clin Invest. 2011 Oct;121(10):3914-23

Intellectual Property: OTT Reference No. E-113-2010 is available for collaboration and licensing

Contact

Mala Dutta, Ph.D.
Office of Translational Research
301-451-2198
Last updated: May 18, 2020