Poliosis is a genetic disorder caused by a defect in the gene that produces the enzyme tyrosine hydroxylase (TH). This enzyme converts tyrosine into dopamine, which plays an essential role in controlling movement and mood. People with poliosis have severe mental retardation and are unable to walk or speak normally. They may appear mentally retarded due to their small size, but they do not suffer from any other physical defects such as blindness or deafness.

The disease affects mainly males. About one out of every 10,000 children born will develop it. The average age at onset is between five and seven years old. There are two types of poliosis: type I and type II.

Type I occurs in boys while type II occurs in girls. Both types affect different parts of the body; however, the symptoms vary considerably among them.

Type I poliosis is characterized by a slow growth rate and developmental delay. Children with this condition grow slowly until they reach puberty, when they begin to accelerate their growth rate. This acceleration usually continues throughout childhood and adolescence. However, there are cases where the acceleration stops before reaching adulthood.

Most affected individuals live into their twenties and thirties without developing any health problems. Some adults may experience some cognitive impairment, though most never show signs of dementia or other forms of memory loss.

Type II mainly affects children who are otherwise normal. Unlike type I, type II does not include any signs of a slow growth rate or developmental delay. Girls with this form of the disease are more likely to experience learning difficulties and other symptoms similar to those found in attention deficit hyperactivity disorder (ADHD).

There is a third form of poliosis, known as type III, which is exceedingly rare. It usually affects infants. Children with this form usually suffer from severe developmental delays, but usually do not experience growth problems.

How is poliosis diagnosed?

At birth, children can be misdiagnosed with Down syndrome or another genetic condition that results in stunted development (generalized or partial). Children with type II poliosis are often misdiagnosed as having ADHD. It is not until the age of 6 that a pediatrician suspects the disease and orders a series of tests to rule out other conditions. It is important that parents be aware of the signs and symptoms of this disease so they can take their child to a doctor if they notice anything unusual.

How is it treated?

Unfortunately, there is no cure for poliosis. However, a healthy diet and good nutrition may help minimize some of the effects of this devastating condition. There are also drugs that can help treat some of the complications that develop as a result of the disease.

What is the prognosis?

The prognosis for people with poliosis is poor. Most affected individuals die early in life, usually due to a heart attack or stroke.

What research is being done?

The National Institute of Neurological Disorders and Stroke (NINDS) is involved in research relating to several neuromuscular diseases, including poliosis. Many scientists are working to find better ways to treat, prevent, and cure these disorders. The Institute recently launched a website to educate patients and their families about the disorders and provide them with up-to-date scientific information. Other organizations, such as the Muscular Dystrophy Association (MDA), also provide patient support and funding for research.


Appel, K. M. and A. D.

Lawrence. (2004). The Muscular Dystrophies: Molecular and Cellular Mechanisms. New York: Cambridge University Press.

NINDS Disorders of the Nervous System Web Site, December 2010.

Muscular Dystrophy Association Website, December 2010.

Muscular Dystrophy Fact Sheet, December 2010.

Siegel, B.V. (2008). The Immune System.

New York: DK Publishing.

Sources & references used in this article:

Topical prostaglandin f2α analog induced poliosis by CS Chen, J Wells, JE Craig – American journal of ophthalmology, 2004 – Elsevier

Poliosis circumscripta: overview and underlying causes by R Sleiman, M Kurban, F Succaria, O Abbas – Journal of the American …, 2013 – Elsevier

Poliosis overlying a neurofibroma by BS Koplon, L Shapiro – Archives of dermatology, 1968 – jamanetwork.com

Uveitis associated with poliosis and vitiligo in six dogs. by TJ Kern, DK Walton, RC Riis, TO Manning… – Journal of the …, 1985 – ncbi.nlm.nih.gov

Uveitis with dysacousia, alopecia and poliosis by B Rones – Archives of Ophthalmology, 1932 – jamanetwork.com

Postherpetic poliosis by JJ Wu, DB Huang, SK Tyring – Archives of dermatology, 2006 – jamanetwork.com


The prevalence of vitiligo and poliosis in patients with uveitis by JJ Nordlund, NT Taylor, DM Albert, MD Wagoner… – Journal of the American …, 1981 – Elsevier