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NEI: nearly one in 10 have ‘rare’ health conditions

May 1, 2012

Rare health conditions are not as unusual as the name might indicate, according to the National Institutes of Health (NIH). And rare eye conditions are no exception, the NIH’s National Eye Institute (NEI) adds.

“Comprehensive eye examinations provide an opportunity for the diagnosis of health conditions, rare and common, ocular and systemic,” noted Gregory S. Wolfe, O.D., MPH, chair of the AOA Health Promotion Committee.

In the United States, a disease is considered rare if it affects fewer than 200,000 Americans, noted Paul A. Sieving, M.D., Ph.D., director of the NEI, in a statement issued to commemorate Rare Disease Day (Feb. 29).

Scientists have identified more than 7,000 rare diseases. Some affect only a few hundred people.

But considered together, rare diseases affect 25 million Americans, which means about 1 in every 10 people has a rare disease, Dr. Sieving observed.

Many of those rare diseases affect vision, Dr. Sieving said.

Rare Disease Day, an awareness-raising event, was observed by the NIH this year for the fifth time in an effort to increase support for research on rare health conditions.

However, the event also serves to spotlight the need for adequate awareness of rare conditions among health care practitioners, including optometrists.

“People with rare diseases, and their families, have unique challenges, beginning with obtaining an accurate diagnosis, which is often delayed due to limited knowledge and awareness in the medical community,” Dr. Sieving said.

Many rare diseases manifest during infancy or childhood, according to the NIH.

At least one condition on the NIH’s rare disease list – retinoblastoma – has been diagnosed in the course of InfantSEE® examinations, Dr. Wolfe noted.

Rare Disease Day also serves to call attention to the growing importance of genetics in the diagnosis and treatment of rare conditions – and the role genetics could play in optometric practice over the coming years, Dr. Wolfe said.

Inherited gene defects account for 80 percent of rare diseases, including many of those with ocular manifestations, Dr Sieving said.

“Recent advances in gene technology are illuminating our understanding of the causes of rare diseases and quickening the translation of discoveries into new treatments,” Dr. Sieving said.

“NEI scientists have successfully used gene therapy to improve vision in people with Leber congenital amaurosis, a rare genetic disorder that causes blindness through the degeneration of photoreceptor cells – the rods and cones in the layer of tissue in the back of the eye called the retina,” Dr. Sieving said. “Gene therapy helps restore gene function by inserting copies of normal, functioning genes into cells. Although vision gains were modest, successful demonstration of the strategy holds promise for treating other degenerative retinal disorders such as retinitis pigmentosa (RP). In January 2012, NEI scientists successfully used gene therapy to treat dogs with a condition similar to RP and are making plans to test the therapy in humans.”

EyeGENE, an NEI-sponsored collaborative network for ophthalmic research, is helping diagnose patients with eye-related genetic diseases while enabling researchers to study and characterize these rare condition, Dr. Sieving said.

Through a network of federally certified molecular diagnostic testing labs, patients who participate in eyeGENE can gain access to free genetic testing, which is often expensive and not covered by health insurance.

EyeGENE currently offers testing, at labs across the country, for more than two dozen rare genetic conditions. In exchange for free genetic testing, participants contribute their clinical and genetic information to the confidential eyeGENE registry.

As researchers develop potential treatments, eyeGENE will help facilitate patient recruitment for clinical trials, Dr. Sieving said.

To help people living with low vision and blindness maintain or increase their independence, the NEI funds the development of assistive technologies and devices through Small Business Innovation Research awards and other grants.

For example, Second Sight, a major recipient of NEI funding, has successfully developed a retinal prosthesis, essentially an externally worn digital camera wirelessly coupled to an electrode grid implanted on the retina inside the eyes that restores limited vision to people with RP, Dr. Sieving noted.

The NIH Office of Rare Disease Research (ORDR) offers a variety of resources to help both health care practitioners and the general public find information on rare health conditions.

A “Rare Diseases and Related Terms” roster on the office’s website (http://rarediseases.info.nih.gov) lists almost 50 rare eye conditions.

The site also offers links to detailed databases of rare clinical disorders maintained by Orphanet, a rare disease and orphan drug portal (www.orphanet.org):

Additional information on rare diseases may be found at www.rarediseaseday.org and on the website of the observance’s sponsor organization, Eurodis, a European advocacy group for patients with rare diseases (www.eurordis.org).

Additional information may also be found on the NEI website (www.nei.nih.gov).

Selected rare eye conditions

The NIH Office of Rare Disease Research’s (ORDR) list of “Rare Diseases and Related Terms” includes nearly 50 eye conditions, including:

  • Schmid-Fraccaro syndrome, or cat eye syndrome (CES) — Cat eye syndrome is a rare chromosomal disorder that may be evident at birth. The name “cat eye syndrome” is derived from a distinctive eye abnormality present in some affected individuals. This feature consists of partial absence of ocular tissue coloboma, often affecting both eyes. Affected ocular tissues may include the iris, choroid, and/or retina.
  • Muscle eye brain disease (MEB) – Muscle eye brain disease is a rare form of congenital muscular dystrophy. Individuals with this condition are born with hypotonia, severe myopia, glaucoma, and brain abnormalities. They also have developmental delay and intellectual disability. People with muscle eye brain disease frequently have additional eye abnormalities, hydrocephalus, and distinctive facial features. This condition is caused by mutations in a gene identified as POMGNT1, and it is inherited in an autosomal recessive pattern. The signs and symptoms of this condition vary among affected individuals, even among members of the same family.
  • Benign concentric annular macular dystrophy (Bull’s eye maculopathy) — Macular dystrophy, concentric annular, is a progressive autosomal dominant macular dystrophy characterized by parafoveal hypopigmentation followed by a retinitis pigmentosa-like phenotype (nyctalopia and peripheral vision loss) with a bull’s eye configuration.
  • Al Gazali syndrome (Al Gazali Al Talabani syndrome, eye defects arachnodactyly cardiopathy) — This syndrome is characterized by ocular colobomas, ichthyosis, endocrine abnormalities (including developmental anomalies of the pituitary gland), cerebral malformations and intellectual deficit. It has been described in three children from one family. The syndrome shows significant clinical overlap with CHIME syndrome and septooptic dysplasia; however, patients with Al-Gazali-Dattani syndrome lack the deafness, seizures, oligodontia, and hair abnormalities present in CHIME syndrome and the optic nerve hypoplasia present in septooptic dysplasia.
  • Forsius Eriksson type ocular albinism, or Aland Island eye disease (AIED) — Aland Island eye disease is an X-chromosomal disorder characterized by reduced visual acuity, progressive axial myopia, regular astigmatism, latent nystagmus, foveal hypoplasia, defective dark adaptation, and fundus hypopigmentation. The syndrome was originally reported in 1964 in a family on the Aland Islands.

An expanded list of rare eye conditions can be accessed using the “Rare Diseases and Related Terms” search function on the NIH OORDR website (http://rarediseases.info.nih.gov).

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